Creating a drawing of an electrical circuit diagram in CAD "P-CAD 2006 SP2"

Electrical diagrams are not drawn to scale. The actual location of components on the wiring field is not taken into account when drawing electrical circuits. The selected format size of the sheet on which the diagram drawing is displayed should ensure compactness and clarity when reading the details of the diagram.

An electrical diagram shows symbols of components, electrical connections between them, text information, tables, alphanumeric symbols and basic inscriptions on the circuit format.

The lines on all diagrams of one project are made with a thickness of 0.2 to 1 mm. Connections and symbols of components are made with lines of the same thickness. Thickened lines draw harnesses (common busbars). Each connection, when connected to the harness, is marked with a number or its name and must be connected at a right angle or at an angle of 45°.

After setting up the configuration of the P-CAD Schematic graphic editor and if the library contains all the component symbols contained in a given electrical diagram (current project), you can begin to create the latter. The sequence of actions is as follows:

Download the P-CAD Schematic graphic editor.

Configuring the Editor . When setting up, click the EditTitleSheets button, then in the Titles splash screen in the TitleBlock area, click the Select button, select the file with the finished format and click the Open button. Let's close all previous windows. An image of a format with fields will appear on the screen.

Let's execute the command to fill in information about the project File/DesignInfo/Fields, then sequentially highlight the necessary lines, click the Properties button and fill the Value window with the desired text in the FieldProperties splash screen. After entering each category of data, click OK. Data entered when editing the diagram:

The list of data can be expanded (Add button) or reduced (Delete button).

Current data, which is updated periodically:

Current Date - current date;

Current Time - current time;

Filename - file name;

Number of Sheets - number of sheets of the project;

Sheets Number - number of the current sheet.

Let's execute the Place/Field command. As a result, a dialog box of the same name will open, in which we select the name of the information field Title (name of the drawing) and click OK. Then place the cursor in the desired format field (the field should be sufficiently scaled) and click the mouse. Text will appear with the name of the project or current sheet if the name was previously entered using the Options/Sheets command.

A long time ago, in a galaxy far, far away, when I was still working in a mid-budget design organization, after yet another “n-th” rework of a project (in AutoCAD) “from scratch,” I decided: “I’ve had enough!” »

Here we need to make a small digression for non-designers: the closer to the end of the project, the more effort you have to spend redoing the project if the task from subcontractors has changed. In 80% of cases - alterations of the so-called. “design”, i.e. routine work: marking equipment, counting all equipment, products, materials and compiling them into specifications, compiling a cable log, generating (drawing) circuit diagrams of the network.

Those. I urgently needed specialized CAD. Which would automate the process, reducing the risk of errors caused by the so-called “human factor” in the design documentation to a minimum.

With this thought, I turned to my superiors: “How long?!” “The top”, in this case, gave the answer: “Where is the money, Zin?!” That is, they demanded justification for the profitability of additional investments in software (“How fast, how fast?!”), personnel training (“When the hell?!”), etc. After which, my colleague and I conducted a small analysis of CAD for electricians, and summarized the results of the analysis in a table:

The table below shows the most common CAD systems,
used to carry out the electrical part of projects.

CAD name			Area of ​​use
		Automated power design
nanoCAD Electro		electrical equipment (EM) and internal
		civilian objects.
Project Studio CS Electrics
v.5

	Computer-aided design:
	* ALPHA SA: CAD Automation Systems;
	* ALPHA SE: CAD of Power Electrics
Alpha	(power supply and distribution networks);
	* ALPHA NKU: CAD Low Voltage
	Complete devices (NKU), mixed systems
	automation and electricians.
	Automates the execution of design work on
	power supply of objects.
	Program composition:
	* Scheme generation subsystem
	power supply of the facility as in the format
	placement of equipment and laying of power lines on
WinELSO v 7.0	plans, and the format of distribution diagrams
	devices;
	* Subsystem for performing electrical engineering
	calculations;
	* Lighting engineering subsystem
	calculations.
	Compass - electric lighting: system
	electric lighting for residential, public and
	industrial buildings.
	KOMPAS-Electric Express: system
	computer-aided design
	electrical diagrams and lists of elements.
	KOMPAS-Electric Pro: designed for
	kit design automation
	documents for electrical equipment of objects
Compass	production based on programmable logic
	controllers (PLC).
	KOMPAS-Electric Std: designed for
	design automation
	electrical equipment of production facilities. IN
	can act as production objects
	any objects in which to perform
	electrical connections are used wired
	installation (low-voltage complete devices
	(NKU), relay protection and automation systems
	(relay protection systems), automated process control systems, etc.).
	Automated design of internal
MagiCAD Electrical supply	electric lighting and power
	power supply for residential, public and
	industrial buildings and structures.

	Lighting design application,
CADprofi	low-voltage systems, power plants,
	overhead power lines, systems
	alarm system.
	Preparation of electrical energy diagrams
MODUS	objects, relay protection schemes, images
	control panels and relay protection panels and
	automation.
	Automated execution of projects in parts
ELF	power electrical equipment (EM) and internal
	electric lighting (EL) industrial and
	civil construction projects.
	For the design of instrumentation and control systems and process control systems:
	* automation scheme
	* electrical circuit diagram
	* diagram of external connections (wiring)
	* drawings of cabinets and panels
	* design documentation
	* equipment layout plan
	To design energy circuits:
E3.series	* main diagram
	* block diagrams of relay protection and control systems
	* schematic diagrams of equipment
	* cabinet drawings
	* diagrams of power and information networks
	* equipment layout plans
	* logical blocking circuits
	The program is designed for designing
	power supply systems, electrical equipment,
HTE	fire and security alarm systems
	access control and video surveillance, communication systems
	and local computer networks.
AutoCAD® Electrical	Design of electrical control systems.
	Designed to automate design work
CADElectro	when creating electrical control systems for
	base of contact equipment and programmable
	controllers.
CADdy++Electrical Engineering	Design of fundamental electrical
	schemes

In addition to the above-listed CAD systems, which allow you to automate the design of electrical documentation, many large manufacturing companies uh electrical equipment companies, such as Schneider Electric, ABB, Legrand, independently produce software that allows you to automate the design of low-voltage complete devices - NKU, the assembly of which is carried out on the basis of electrical products produced by these companies.

Having analyzed the scope of application of each of the above CAD systems, my colleague and I selected for comparison those systems that were suitable for us by type of activity. Those. which allow you to automate the design of internal electric lighting systems and power electrical equipment of buildings, and made a price analysis, the results of which are given below. (prices have now changed, because the study was conducted several years ago, but the price ratio remains the same):

Each of the above CAD systems allows you to automate the following stages of design work:

calculation of illumination and automatic placement of lamps in the room;

arrangement of equipment and laying of cable routes; laying cables along cable routes;

carrying out all necessary electrical calculations; selection of settings for protective devices and cable sections;

and based on the results, forms the following project documents:

plans for the location of equipment and laying of cable routes; schematic diagrams of distribution and supply networks; specification of equipment, products and materials;

cable magazine; group board tables; reports with the results of lighting and electrical calculations.

As you can see, the main difference between CAD is the presence and type of base platform.
Most computer-aided design systems for electrical engineering sections of project documentation are based on the AutoCAD program, which is explained by the widespread use of this program in organizations involved in design activities.

The use of the AutoCAD program as a basic CAD platform makes it possible for the interaction of related designers of various enterprises, regardless of which computer-aided design system is used to work in a particular organization, but at the same time, as can be seen from the table, it increases the cost of CAD implementation.

A computer-aided design system that has its own graphics core as a base platform is nanoCAD Electro, which significantly reduces the cost of its acquisition and use. In addition, this program, like AutoCAD, supports the DWG format. The presence of its own graphics core makes nanoCAD Electro independent of other graphics systems, and support for the DWG format facilitates the exchange of information with partners and customers.

In addition, the table shows for comparison the CADprofi v 7.1 system, the use of which for computer-aided design requires the installation of the Bricscad program, which is an alternative DWG CAD platform.

After purchasing a CAD software product, you need to implement it:

You need to install and configure: libraries of materials, templates, a database of standard products and documents; a database of specific elements that meet the needs of a specific design organization and are not included in the standard database.

You need to learn to work effectively in a system whose functionality is so wide that independently mastering the basic capabilities without a methodological understanding of the system as a whole will require significant time expenditure.

Understand the program interface, because the more specialized the program, the more “undocumented” details it contains.

Learn to distinguish a “bug” from a “feature”. And use (or neutralize) them in your work.

All of the above factors determine the user’s need for support from the manufacturer, so-called technical support.
Technical support resolves most issues related to setting up and operating software products.
Forms of technical support can be very different: updating versions of a software product, conducting training, conducting consultations:

at the supplier's office; with a technical support specialist visiting the design organization directly; by phone; by email; online.

Certain types of technical support require special conditions. So, for example, to receive expert advice online, you must: have a designer headphone and microphone available at the workplace; setting up remote access for CAD developers; the desire of developers to customize the program to the corporate standards of the design organization.

That is, when determining the cost of implementing a computer-aided design system, it is necessary to take into account: the price of the CAD itself, and the price of the software that is the base platform for CAD, and the costs of technical support.
Moreover, in my opinion, the determining factor for the end user here is the availability of technical support. Those. Before purchasing special software, you need to make sure whether the developer has enough resources to provide technical support on the scale required by the user. (Of course, the ideal option is to know the technical support Skype login...?).

At the same time, technical support is necessary not only for the period when design engineers master a new software product for them, which is a computer-aided design system, but also for the entire subsequent period of operation of the CAD system.
Based on the above, my colleague and I settled on the program: nanoCAD Electro. At the first stage, we were guided, of course, by price.

After the materials were provided, the company's management refused to update the software, citing the fact that the materials did not indicate the time frame for mastering the software, as well as the benefits of mastering the program. Now, three years after starting work in the program, I can say:
1. To initially master the program, you will need at least 2 months. (this is if you master it alone, and from scratch)
2. Date of entry into the “working” design mode: six months, which is explained by the following factors: creation of our own database, adjustment of templates to corporate requirements, and most importantly: psychological adaptation to the program.
3. Time savings during design range from 0 to 50%, depending on the project and user qualifications. Basically, of course, it depends on the user.

4. Savings when adjusting: from my own experience: a week ago I adjusted the project. If done manually, it would take me a week (5 working days), but for the nanoCAD Electro program it took 1.5 days.

All this data is provided, subject to maintaining the QUALITY of the design work.

The times of using drawing boards are long gone; they were replaced by graphic editors, these are special programs for drawing electrical circuits. Among them there are both paid applications and free ones (we will consider the types of licenses below). We are confident that the brief overview we have created will help you choose from a variety of software products the software that is most optimal for the task at hand. Let's start with the free versions.

Free

Before moving on to the description of the programs, we will briefly talk about free licenses, the most common of which are the following:

• Freeware– the application is not limited in functionality and can be used for personal purposes without a commercial component.
• Open Source– an “open source” product, into which you can make changes by adjusting the software to your own tasks. There may be restrictions on commercial use and paid distribution of modifications made.
• GNU GPL– a license that practically does not impose any restrictions on the user.
• Public domain– almost identical to the previous version; copyright protection laws do not apply to this type of license.
• Ad-supported– the application is fully functional and contains advertisements for other products of the developer or other companies.
• Donationware– the product is distributed free of charge, but the developer offers to make donations on a voluntary basis for the further development of the project.

Having gained an understanding of free licenses, you can move on to software distributed under such conditions.

Microsoft Visio

This is an easy-to-use, but at the same time very convenient vector graphics editor with a rich functionality. Despite the fact that the main socialization of the program is the visualization of information from MS Office applications, it can be used to view and print radio circuits.

MS releases three paid versions that differ in functionality and a free version (Viewer), which is integrated into the IE browser and allows you to view files created in the editor. Unfortunately, to edit and create new diagrams you will need to purchase a full-featured product. Note that even in the paid versions, among the basic templates there is no set for fully creating radio circuits, but it is not difficult to find and install.

Disadvantages of the free version:

• The functions of editing and creating diagrams are not available, which significantly reduces interest in this product.
• The program only works with the IE browser, which also creates a lot of inconvenience.

Compass-Electric

This software is an application to the CAD system of the Russian developer ASCON. For its operation, the installation of the KOMPAS-3D environment is required. Since this is a domestic product, it fully supports the GOST standards adopted by Russia, and, accordingly, there are no problems with localization.

The application is intended for designing any types of electrical equipment and creating sets of design documentation for them.

This is paid software, but the developer gives you 60 days to familiarize yourself with the system, during which time there are no restrictions on functionality. On the official website and on the Internet you can find a lot of video materials that allow you to familiarize yourself with the software product in detail.

In the reviews, many users note that the system has a lot of shortcomings that the developer is in no hurry to fix.

Eagle

This software is a comprehensive environment in which you can create both a schematic diagram and a printed circuit board layout for it. That is, place all the necessary elements on the board and perform tracing. Moreover, it can be performed either automatically or manually or by a combination of these two methods.

The basic set of elements does not contain models of domestic radio components, but their templates can be downloaded on the Internet. The application language is English, but localizers allow you to set the Russian language.

The application is paid, but it is free to use with the following functional limitations:

• The size of the mounting plate cannot exceed 10.0 x 8.0 cm.
• When routing, only two layers can be manipulated.
• The editor allows you to work with only one sheet.

Dip Trace

This is not a separate application, but a whole software package that includes:

• Multifunctional editor for developing circuit diagrams.
• Application for creating circuit boards.
• A 3D module that allows you to design housings for devices created in the system.
• A program for creating and editing components.

The free version of the software package, for non-commercial use, has minor restrictions:

• Circuit board no more than 4 layers.
• No more than one thousand pins from components.

The program does not provide Russian localization, but it, as well as a description of all functions of the software product, can be found on the Internet. There are also no problems with the component database; initially there are about 100 thousand of them. On thematic forums you can find component databases created by users, including those for Russian GOSTs.

1-2-3 scheme

This is a completely free application that allows you to equip Hager electrical panels with the equipment of the same name.

Program functionality:

• Selecting a housing for an electrical panel that meets the standards for the degree of protection. The selection is made from the Hager model range.
• Complete with protective and switching modular equipment from the same manufacturer. Please note that the element base contains only models certified in Russia.
• Formation of design documentation (single-line diagram, specification that meets ESKD standards, drawing of appearance).
• Creation of markers for electrical switchboard switching devices.

The program is completely localized for the Russian language, its only drawback is that the element base contains only the electrical equipment of the developer company.

Autocad Electrical

An application based on the well-known CAD system Autocad, created for designing electrical circuits and creating technical documentation for them in accordance with ESKD standards.

Initially, the database includes over two thousand components, while their conventional graphic symbols meet current Russian and European standards.

This application is paid, but you have the opportunity to get acquainted with the full functionality of the basic working version within 30 days.

Elf

This software is positioned as an automated workstation (AWS) for electrical designers. The application allows you to quickly and correctly develop almost any drawing for electrical projects linked to the floor plan.

The functionality of the application includes:

• Arrangement of UGO when designing electrical networks laid openly, in pipes or special structures.
• Automatic (from the plan) or rune calculation of the power circuit.
• Drawing up specifications in accordance with current standards.
• Possibility of expanding the element base (UGO).

The free demo version does not allow you to create or edit projects; you can only view or print them.

Kicad

This is a completely free open source software package. This software is positioned as an end-to-end design system. That is, you can develop a circuit diagram, use it to create a circuit board and prepare the documentation necessary for production.

Characteristic features of the system:

• The use of external tracers is allowed for board layout.
• The program has a built-in printed circuit board calculator; elements can be placed on it automatically or manually.
• Upon completion of the tracing, the system generates several technology files (for example, for a photoplotter, drilling machine, etc.). If desired, you can add a company logo to the PCB.
• The system can create layer-by-layer printouts in several popular formats, as well as generate a list of components used in development for order generation.
• It is possible to export drawings and other documents to pdf and dxf formats.

Note that many users note that the system interface is poorly thought out, as well as the fact that in order to master the software, you need to thoroughly study the documentation for the program.

TinyCAD

Another free and open source application that allows you to create circuit diagram drawings and has the functions of a simple vector graphics editor. The basic set contains forty different component libraries.

TinyCAD - a simple editor for circuit diagrams

The program does not provide PCB tracing, but it does have the ability to export the netlist to a third-party application. Export is carried out with support for common extensions.

The application only supports English, but thanks to the intuitive menu there will be no problems with mastering it.

Fritzing

Free project development environment based on Arduino. It is possible to create printed circuit boards (the layout must be done manually, since the auto-routing function is frankly weak).

It should be noted that the application is “sharpened” for quickly creating sketches that make it possible to explain the principle of operation of the designed device. For serious work, the application has a too small base of elements and a very simplified diagram.

123D Circuits

This is a web application for developing Arduino projects, with the ability to program the device, simulate and analyze its operation. A typical set of elements contains only basic radio components and Arduino modules. If necessary, the user can create new components and add them to the database. It is noteworthy that the developed printed circuit board can be ordered directly from the online service.

In the free version of the service, you cannot create your own projects, but you can view other people’s developments that are in the public domain. For full access to all features, you must subscribe ($12 or $24 per month).

Note that due to its poor functionality, the virtual development environment is of interest only to beginners. Many of those who used the service drew attention to the fact that the simulation results differed from real indicators.

XCircuit

Free multi-platform application (GNU GPL license) for quickly creating circuit diagrams. The functional set is minimal.

The application language is English, the program does not accept Russian characters. You should also pay attention to the atypical menu, which you need to get used to. In addition, contextual hints are displayed on the status bar. The basic set of elements includes UGO of only the main radio components (the user can create his own elements and add them).

CADSTAR Express

This is a demo version of the CAD software of the same name. Functional limitations affected only the number of elements used in the development circuit (up to 50 pieces) and the number of contacts (no more than 300), which is quite sufficient for small amateur radio projects.

The program consists of a central module, which includes several applications that allow you to develop a circuit, create a board for it and prepare a package of technical documentation.

The basic set includes more than 20 thousand components; additional libraries can be downloaded from the developer’s website.

A significant drawback of the system is the lack of support for the Russian language; accordingly, all technical documentation is also presented online in English.

QElectroTech

A simple, convenient and free (FreeWare) application for developing electrical and electronic circuit drawings. The program is a regular editor; no special functions are implemented in it.

The application language is English, but there is a Russian localization for it.

Paid applications

Unlike software distributed under free licenses, commercial programs, as a rule, have much more functionality and are supported by developers. As an example, we will give several such applications.

sPlan

A simple editor program for drawing electrical circuits. The application comes with several component libraries that the user can expand as needed. You can work with several projects simultaneously by opening them in separate tabs.

Drawings made by the program are stored as vector graphics files in its own format with the “spl” extension. Conversion to standard raster image formats is allowed. It is possible to print large diagrams on a regular A4 printer.

The application is not officially released in Russian localization, but there are programs that allow you to Russify the menu and contextual hints.

In addition to the paid version, there are two free implementations, Demo and Viewer. In the first one there is no way to save and print the drawn diagram. The second provides only the function of viewing and printing files in the “spl” format.

Eplan Electric

Multi-module scalable CAD system for developing electrical projects of varying complexity and automating the process of preparing design documentation. This software package is now positioned as a corporate solution, so it will not be of interest to ordinary users, especially if you take into account the cost of the software.

Target 3001

A powerful CAD complex that allows you to develop electrical circuits, trace printed circuit boards, and simulate the operation of electronic devices. The online library of components contains more than 36 thousand different elements. This CAD is widely used in Europe for PCB routing.

The default language is English, it is possible to set the menu in German or French, there is no official Russian localization. Accordingly, all documentation is presented only in English, French or German.

The cost of the simplest basic version is about 70 euros. For this money, tracing of two layers with 400 pins will be available. The cost of the unlimited version is around 3.6 thousand euros.

Micro-Cap

An application for modeling digital, analog and mixed circuits, as well as analyzing their operation. The user can create an electrical circuit in the editor and set parameters for analysis. After this, with one click of the mouse, the system will automatically perform the necessary calculations and display the results for study.

The program allows you to establish the dependence of the parameters (ratings) of elements on temperature conditions, illumination, frequency characteristics, etc. If the circuit contains animated elements, for example, LED indicators, then their state will be displayed correctly, depending on the incoming signals. During modeling, it is possible to “connect” virtual measuring instruments to the circuit, as well as monitor the state of various components of the device.

The cost of the full-featured version is about $4.5 thousand. There is no official Russian localization of the application.

TurboCAD

This CAD platform includes many tools for designing various electrical devices. A set of special functions allows you to solve engineering and design problems of any level of complexity.

Distinctive features are fine-tuning of the interface for the user. Lots of reference books, including in Russian. Despite the lack of official support for the Russian language, there are Russifiers for the platform.

For ordinary users, purchasing a paid version of the program in order to develop electrical circuits for amateur devices will be unprofitable.

Designer Schematic

An application for creating electrical circuits using radioelements produced by Digi-Key. The main feature of this system is that the editor can use mechanical design to build circuits.

Component databases can be checked for compliance at any time and, if necessary, updated directly from the manufacturer’s website.

The system does not have its own tracer, but the netlist can be loaded into a third-party program.

It is possible to import files from popular CAD systems.

The approximate cost of the application is about $300.

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Design of printed circuit boards of electronic devices in CAD P-CAD

• Introduction
• 1. General information about the P-CAD design system
• 1.1 Functionality and structures of the P-CAD system
• 1.2 Stages of designing a printed circuit board in the P-CAD system
• 2. Creation of a circuit diagram of a control device for cyclic industrial robots
• 2.1 Description of the electrical circuit diagram
• 2.2 General information about the Schematic graphic editor
• 2.3 Creating a circuit diagram of P-CAD 2004
• 2.4 Checking the circuit and displaying errors
• 2.5 Generating a netlist
• 3. Create a device circuit board
• 3.1 PCB Editor Basics
• 3.2 PCB tracing
• 3.3 Automatic tracing
• 3.4 Checking the printed circuit board for errors
• 4. Circuit modeling
• 4.1 General information about the modeling process in P-CAD 2004
• 4.2 Modeling a section of a logic module circuit
• 5. Development of guidelines for the use of CAD P-CAD 2004
• 6. Safety and environmental friendliness of work
• 6.1 Analysis of harmful and dangerous factors
• 6.2 Industrial sanitation
• 6.3 Safety precautions
• 6.4 Environmental protection
• 6.4.1 Air pollution
• 6.4.2 Hydrospheric pollution
• 7. Feasibility study
• 7.1 Planning a set of works
• 7.2 Calculation of development costs
• 7.3 Calculation of the estimated development price
• 7.4 Assessing the organizational effectiveness of the project
• Conclusion
• Conclusion
• List of sources used
• Appendix A
• Appendix B
• Appendix B

Introduction

The purpose of the work is to design, using the P-CAD 2004 software product, printed circuit boards of four electronic devices, including the printed circuit board of the logic device module for controlling cyclic robots, to test the P-CAD 2004 Mixed-Circuit-Simulator modeling tools using the example of part A of the logic module circuit and development of guidelines for the design of printed circuit boards of electronic devices and modeling in CAD P-CAD 2004.

At the same time, the problems of creating a basic electronic circuit and printed circuit board of the device, as well as the problem of modeling, will be solved.

For the convenience of the user, guidelines will be developed for using a circuit editor, a printed circuit board editor and a simulation program, which can be recommended for use in educational institutions to help master this software product.

1. General information about the P-CAD design system

1.1 Functionality and structures of the P-C system AD

The P-CAD system is designed for end-to-end design of analog digital and analog-to-digital devices. This system allows you to perform a full cycle of printed circuit board design, including the creation of symbols for electrical radio elements, input and editing of electrical circuits, packaging of circuits on a printed circuit board, manual and interactive placement of components on the board, manual, interactive and automatic routing of conductors, error control in the circuit and printed circuit board, mixed analog-digital modeling and production of design and technological documentation.

Entering the circuit begins with placing components and group communication lines on the working field of the UGO . Next, the component pins are connected by conductors. If necessary, individual circuit segments located on different sheets and not having direct physical contact are combined by special elements - ports. The edited circuit is checked for errors and a list of components and connections is created for transmission to the printed circuit board editor.

The design of a printed circuit board is carried out in the RSV graphic editor. To do this, the necessary libraries are first connected to the RSV PCB editor and its configuration is configured. The design of a printed circuit board begins by loading the netlist (packing file) created in the circuit editor. At the same time, groups of components appear on the working field with an indication of the electrical connections between them.

Next, the components are placed manually on the surface of the printed circuit board, taking into account the overall layout of the product, electrical, mechanical and thermal connections between them. This uses the Move, Rotate and Align tools for components and their attributes.

The layout of conductors and metallized areas is carried out in manual, interactive or automatic modes, depending on the purpose of the board and production conditions.

After completing the tracing, the project is necessarily checked for errors and violations of technological standards, the project is edited taking into account the results of the check.

At the final stage, taking into account the specific production, files for making templates and drilling files for drilling mounting, transition and fastening holes are prepared and the project is transferred to production.

2. Creation of a circuit diagram of a control device for cyclic industrial robots

2.1 Description of the electrical circuit diagram

The designed logical module is used in the control system of cyclic industrial robots. It forms control actions and controls the execution of generated commands.

This module generates the following output signals:

· address of the input/output module (A0-A3);

· data (D0-D15);

· “ENTER” signal;

· “OUTPUT” signal.

Microcontroller D1 has the following pins:

PSEN - resolution of external program memory; issued only when accessing external ROM;

EA -- disabling internal program memory; level 0 at this input causes the microcontroller to execute the external ROM program only; ignoring the internal one (if the latter is present);

RST -- microcontroller general reset input;

XTAL1, XTAL2 -- pins for connecting a quartz resonator (necessary for setting the operating frequency of the microcontroller);

P0 -- eight-bit bidirectional information input/output port: when working with external RAM and ROM via port lines in time multiplexing mode, the external memory address is issued, after which data is transmitted or received;

P1 is an eight-bit quasi-bidirectional input/output port: each bit of the port can be programmed to both input and output information, regardless of the state of other bits;

P2 is an eight-bit quasi-bidirectional port similar to P1; in addition, the pins of this port are used to provide address information when accessing external program or data memory (if 16-bit addressing of the latter is used). The port pins are used when programming the 8751 to enter the most significant bits of the address into the microcontroller;

RZ is an eight-bit quasi-bidirectional port, similar. P1; In addition, the pins of this port can perform a number of alternative functions that are used when operating timers, the serial I/O port, the interrupt controller, and external program and data memory.

Working with external RAM

1) Read from RAM

The microcontroller generates a logical one at pin P1.7. This turns on the RAM chip. The microcontroller then generates a thirteen-bit address. The first eight bits of the address are formed on port P0. The remaining five are on pins P1.0-P1.4. Based on the read signal generated at pin P3.7, the bidirectional driver D4 switches to transmitting data from the RAM to the microcontroller, and the RAM sends the data stored in the memory cell to the address generated by the microcontroller. Data from RAM is sent to the output of microcontroller P.0.

2) Write to RAM

The microcontroller generates a logical one at pin P1.7. This turns on the RAM chip. The microcontroller then generates a thirteen-bit address. The first eight bits of the address are formed on port P0. The separation of address and data occurs through register D6, to which the microcontroller ALE signal (external memory address signal) is supplied. The remaining five are formed at pins P1.0-P1.4. Based on the read signal generated at pin P3.7, the bidirectional driver D4 switches to transferring data from the microcontroller to RAM. Data is written to a RAM memory cell at an address generated by the microcontroller.

Data output to actuators

Sixteen data bits must be generated at the output of the logical module. The microcontroller can only generate eight in one machine cycle. Therefore, in a logical module, data is formed in two stages: first the high byte, then the low byte. Based on a signal from the pin of the microcontroller P3.7, the bidirectional driver D4 switches to the data transfer mode from the microcontroller. To write the high byte of data to the D7 register, this register must be enabled. To do this, the following signals from the microcontroller are supplied to the D3 decoder:

A logical zero is formed at pin P1.7, so the microcontroller turns on the decoder;

A write signal (logical one) is generated at pin P3.6;

A combination of logical zeros and ones is formed at pins P1.5 and P1.6 (for register D7 a combination of logical zeros is formed at P1.6 and P1.7).

At port P0 of the microcontroller, the most significant byte of data is generated, which is transmitted through the bidirectional driver D4 and written to register D7.

A similar procedure is used to generate and write the low byte of data into the D8 register. The difference lies in the combination at pins P1.5 and P1.6 (for register D8, a logical zero is formed at P1.6, and a logical one at P1.7).

After sixteen data bits are generated, the address of the output module is formed at pins P2.0 - P2.3, which, passing through the unidirectional driver D11, is amplified and transmitted via the address bus to the output modules.

The last stage is the formation of the “OUTPUT” signal at pin P2.5. The “OUTPUT” signal opens microcircuits D12 and D13 and sixteen bits of data are amplified and transmitted via the data bus to the output modules.

Input of data from actuators

At pins P2.0 - P2.3 of the microcontroller, the address of the input module is formed, which is amplified by a unidirectional driver and transmitted via the address bus to the input modules.

At pin P2.4, the “INPUT” signal is generated, which is also transmitted by a unidirectional shaper to the input modules. At the same time, the “ENTER” signal turns on registers D9 and D10, into which sixteen bits of data coming from the input module are written.

Reception of sixteen bits by the microcontroller, as well as transmission, is carried out in two stages. The high byte is received first, then the low byte.

Bidirectional driver D4 is switched on to transmit data to the microcontroller. Using the decoder, the unidirectional driver D14 is turned on and the high byte of data is sent to port P0 of the microcontroller.

The low byte of data is entered in the same way.

2.2 General information about the Schematic graphic editor

Creation of a circuit diagram in P-CAD is carried out in the Schematic circuit editor. The window of this editor is shown in Figure 1.

Figure 1 - Circuit editor screen

The main elements of the schematic editor working screen are the main menu, the top and left toolbars and the work field.

The top and left panels contain icons for calling up the most commonly used commands. The purpose of icons and commands is given in Table 1.

Table 1 Purpose of pictograms

Pictogram	Equivalent menu command
	Place/Part (place element)
	Place/Wire
	Place/Bus
	Place/Port (place port)
	Place/Pin
	Place/Line
	Place/Arc (place an arc)
	Place/Polygon (place a polygon)
	Place/Text (place text)

At the bottom of the screen there is a hint line where system messages about necessary user actions are displayed and a status line displaying the cursor coordinates (246.380; 581.660), the type of grid (Abs) and its step (2.540), the current line thickness (0.762), the name of the current pages. The command status window is available for editing.

The project is configured in the Option menu. Configurations (schematic sheet size, system of measurement units, acceptable angles of orientation of lines and nets, autosave mode, etc.) are set in the Options | Configure (Figure 2).

Figure 2 - Options Configure command window

In this window, select the required size of the workspace (Workspace Size). Checking the A4-A0 checkboxes will result in the European format being set; the A,B,C,D,E checkboxes correspond to the American standard.

It is also possible to set the size of the working area yourself by checking the User checkbox. Units of measurement are selected in the Units section.

To facilitate work, all elements of the circuit on the working field are tied to the nodes of a special grid. Grid parameters (distance between nodes, grid type, its type) are set using the Options Grid command (the window of this command is shown in Figure 3)

Figure 3 - Setting grid parameters

The grid spacing is set in the input field (Grid Spacing). The grid display type is set in the Visible Grid Stile group: in the form of dots (Dotted); in the form of vertical and horizontal lines (Hatched).

The grid type is set in the Mode group. The grid can be absolute (Absolute) or relative (Relative). The absolute grid has the origin in the lower left corner of the work field, and the relative grid has the origin at the point with the coordinates specified in the Relative Grid Origin group, or at the point marked by the user by clicking the left mouse button with the Prompt for Origin checkbox selected. origin).

In the Options Display dialog box (setting screen parameters) you can configure the elements of the working field, including their color design. These settings are of an aesthetic nature and do not affect the operation of the program (Figure 4).

Figure 4 - Setting screen parameters

2.3 Creating a circuit diagram P-C AD 2004

Before entering and placing components on the diagram, you must connect libraries with the necessary components. To do this, in the Library menu, select Library Setup, in which the necessary libraries are installed.

Components are placed using the Place | Part or by clicking the corresponding icon (Table 1). The dialog box for this command is shown in Figure 5.

Figure 5 - Selecting a component from the library

To work with notations close to Russian standards, you must select the IEEE graphics option.

The Library list displays connected libraries. It is possible to add libraries without leaving this menu (Library Setup button).

The component symbol is placed by clicking the mouse button at the required point in the work field.

To move a component, you must select it using. By pressing a key you can rotate the component at an angle of 90 degrees; using the key create a mirror image of it.

It is also possible to copy a component or group of components by holding down the Ctrl key and moving the mouse.

After placing all the components, connections are made between them. The connection is made by conducting circuits and group communication lines (hereinafter referred to as buses).

By command Place | Wire (corresponding icon in Table 1) conducts the circuit. Clicking the left mouse button fixes the starting point of the chain. Each click of the left mouse button fixes the break point. Completing the input of the circuit is done by clicking the right mouse button.

Since the diagram is dominated by vertical and horizontal circuits, in the Options | Configure just set the orthogonality mode to 90/90 Line-Line.

The electrical connection of intersecting circuits is indicated by a Junction point, which is automatically placed on the T-shaped connections.

Selecting the Place command | Bus activates the bus output mode. By clicking the left mouse button, the starting point and the break point of the bus are marked, the construction of which is completed by pressing the right mouse button or the Escape key.

To connect the circuits and the bus, you must first place the bus and then connect the necessary circuits to it.

2.4 Checking the circuit and displaying errors

The created diagram in the Schematic editor must be checked for errors, since if there are any, the PCB design cannot be carried out. After eliminating the shortcomings, you can begin designing the PCB.

To display errors on the circuit, in the Options Display on the Miscellaneous tab in the ERC Errors group, set the display mode for detected circuit errors. When you select the Show switch, detected errors are indicated on the diagram with a special indicator (Figure 6)

Figure 6 - Error indicator

In the Size input field of this group you can set the size of the error indicator, which can vary from 0.025 to 10 mm.

The circuit is checked for errors using the Utils | ERC (Electrical Rules Check). In the menu of this command (Figure 7) a list of checks is specified, the results of which are presented in a text report.

Figure 7 - Setting up ERC configuration

The list of checked errors is given in Table 2.

Table 2 Rules for checking circuits

Validation Rule	What is being checked
Single Node Nets	Chains with a single node
	Chains without nodes
Electrical Rules	Electrical errors when incompatible types of pins are connected, for example, the output of a logic chip is connected to a power supply
Unconnected Pins	Unconnected Symbol Pins
Unconnected Wires	Unconnected circuit segments
Bus/Net Rules	The circuits included in the bus occur only once or not a single wire fits to the bus
	Components placed on top of other components
Net Connectivity Rules	Incorrect ground and power connections
	Errors in creating hierarchical projects

To view the error report, you must enable the View Report option, and to indicate errors on the diagram - Annotate Errors. The priority of errors is set in the Severity Levels window: Electrical Board Module

- Errors - error;

- Warning - warning;

- Ignored - ignore the error.

After entering the required configuration, clicking OK creates an error report and saves it to a file with the *.erc extension.

2.5 Generating a netlist

An important step in working with a schematic is obtaining a component connection list, which can be used in the PCB editor to trace conductors. A netlist includes a list of components and circuits and the pin numbers of the components to which they are connected. This list is used for the so-called procedure of “packing a circuit onto a printed circuit board” - placing component housings on the printed circuit board field, indicating their electrical connections according to the circuit diagram.

To create a list, select Generate Netlist from the Utils menu (Figure 8).

Figure 8 - Selecting the netlist format

In this window, in the Netlist Format list, select the netlist format: P-CAD ASCII, Tango, FutureNet Netlist, FutureNet Pinlist, Master Design, Edif 2.0.0, PSpice, XSpice. To develop PCBs using the PCB graphic editor, the P-CAD ASCII format is selected. By clicking the Netlist Filename button, you must select a netlist file.

Activating the Include Library Information function allows you to include in the netlist file (for P-CAD ASCII format only) the information necessary for compiling, using the Library Manager, a library of symbols for the components located in this project (using the Library | Translate command). This information is not used to design a printed circuit board.

3. Create a device circuit board

3.1 PCB Editor Basics

The P-CAD RSV graphic editor is designed to perform work related to the technology of development and design of printed circuit board assemblies. It allows you to pack circuits onto a board, set the physical dimensions of the board, the width of the conductors and the size of individual gaps for different conductors, set the sizes of contact pads and via diameters, and screen layers. The editor allows you to carry out manual, interactive and automatic routing of conductors and generate control files for process equipment.

This graphic editor has the same interface as Schematic. Differences in the designation of some pictograms. The PCB editor window is shown in Figure 9.

Figure 9 - PCB graphic editor screen

Table 3 Purpose of PCB editor icons

Pictograph.	Equivalent command	Pictograph.	Equivalent command
	Place/Component (place element)		Place/Text (place text)
	Place/Connection (enter electrical connection)		Place/Attribute
	Place/Pad (place pad stack)		Place/Field (place a data line)
	Place Via (place vias)		Place/Dimension (enter size)
	Place/Line		Rote/Manual (draw conductors manually)
	Place/Arc (place an arc)		Rout/Miter (smooth conductor bend)
	Place/Polygon (place a filled polygon that does not have electrical properties)		Route/Bus (route the bus)
	Place/Point (place anchor point)		Rout/Funout (create stringers)
	Place/Copper Pour (place metallization area with different hatching patterns)		Rout/Multi Trace (lay several routes)
	Place/Cutout (place a cutout in the metallization area)		Maximize Hugging (improve obstacle avoidance)
	Place/Keepout (create a trace barrier)		Minimize Length (reduce length)
	Place/Plane (create a dividing line for the metallization layer)		Visible Routing Area (display routing area)
	Utils/Record ECOs (start/end recording of change file)		Push trace

The graphic editor configurations are configured using the Options | Configure (Options | Configurations). To work, you must set the metric system of units and the size of the work area. (In Figure 10, the General tab is the Units and Workspace Size group, respectively). The size of the working area must exceed the size of the designed control panel.

Figure 10 - Options Configure command window

In the Options Grid editor window, just like in Schematic, you can set the size of the grid and the type of its display (dots or lines).

Routing parameters are set on the Route (for manual routing) and Advanced Route (for advanced routing) tabs.

Let's look at the advanced tracing options:

In the Routing Angle group, possible wire layout modes are set (Figure 11)

Figure 11 - Setting tracing parameters

45 Degree - conducting conductors at an angle of 45 and 90 degrees;

90 Degree - use only vertical and horizontal conductors;

Any Angle - conducting conductors at any angle.

In the Routing Mode area, select one of the following wire layout modes:

- Ignore Rules - routes are drawn without taking into account the specified design rules. Tracing in this mode is carried out without taking into account existing obstacles and already laid routes;

- Hug Obstacles - routes are carried out taking into account design rules, bypassing existing obstacles. Objects belonging to the routed circuit are not considered an obstacle;

- Click Plow (Shift after click) - initially the route is drawn in the first mode, but after clicking the left mouse button it is automatically rebuilt taking into account the design rules;

- Interactive Plow - similar to Click Plow mode.

In the Closing Effort group, the degree of straightening of the trace section is set: None, Weak, Strong.

Setting production parameters is carried out on the Manufacturing tab. Here you set the parameters necessary for the production of printed circuit boards.

One of the important differences between P-CAD 2004 and previous versions is the ability to create a circuit board outline in this system. Simple configuration boards can be drawn directly in the PCB editor using arcs and lines for drawing. Boards of complex shapes are best made in drawing and graphic systems like AutoCAD or T-Flex CAD, which have special tools for controlling the angles of inclination of dimensions and line connections. Data exchange between these systems and the PCB editor is done through the universal DFX data format.

When creating a printed circuit board (PCB) in P-CAD, the following main layers are formed:

1) Top - conductors on the top side of the PCB;

2) Top Assy - additional attributes on the top side of the PP;

3) Top Silk - silk-screen printing on the top layer of PP (footprint graphics, position designation);

4) Top Paste - soldering graphics on the top side of the PCB;

5) Top Mask - solder mask graphics on the top side of the PCB;

6) Bottom - conductors on the bottom side of the PCB;

7) Bottom Assy - attributes on the bottom side of the PP;

8) Bottom Silk - silk-screen printing on the bottom layer of PP;

9) Bottom Paste - soldering graphics on the bottom side of the PCB;

10) Bottom Mask - solder mask graphics on the bottom side of the PCB;

11) Board - borders of the PP.

In addition to these layers, any others can be installed (up to 999 pieces).

Before placing components or a packaged circuit diagram on the board, you must include libraries using the Library | Setup or by clicking the corresponding icon (Table 3). The library window view is shown in Figure 12.

Figure 12 - Component placement window

3.2 PCB tracing

Routing is the process of laying out conductors for printed circuit wiring. There are several possibilities for this procedure in the P-CAD system.

1. Manual tracing. For this purpose, the P-CAD system offers tools that can be divided into three groups:

· tools for manual tracing;

· interactive tracing tools;

· special tools.

To manual tracing tools can be attributed to Route Manual, with the help of which the laying of routes is done entirely manually in strict accordance with the developer’s plan. The system in this case plays the role of an electronic drawing board, exercising passive control over compliance with technological norms and rules. Interactive Tracing Tools more intelligent. The developer specifies only the direction of a fragment of the route, and the system generates it itself, taking into account the accepted routing rules. If desired, it is possible to automatically complete a started trace and automatically adjust fragments of already laid traces (Push Traces mode - pushing apart traces).

2. Interactive tracing is more intelligent than the previous manual tracing command. It allows you to quickly create routes taking into account technological norms and rules. The laying of routes can be carried out either fully automatically, avoiding obstacles, or under the control of the developer.

Compared to previous versions, P-CAD 2004 has a new, more powerful and improved interactive router (Advanced Route).

Enhanced tracing has a number of additional capabilities over regular interactive tracing.

Tracing can start on top of an existing route, snapping to its center regardless of the set step; the “rubber thread” of the traced (unfixed) segment is displayed using the current highlight color. During routing, the following wire layout modes are possible: 45-degree (diagonal), orthogonal, and any angle.

When continuing a suspended line or starting a new one after completing the previous one, the line width becomes equal to the nominal value , if it is specified for the corresponding circuit in the design rules. When performing rectifications, the router will always try to reduce the amount of copper placed (and therefore the length of the circuit).

3. Automatic tracing

This type of routing can be carried out using various built-in autorouters. A distinctive feature of the latest version of P-CAD is the second generation router SitusTM Topological Autorouting, also included in the Protel DXP package.

Mandatory components of the P-CAD system, starting with ACCEL EDA 12.00, are the QuickRoute, ProRoute 2/4 and ProRoute routers, as well as the interface to the SPECCTRA auto-routing and auto-placement program from Cadence.

Shape-Based Autorouter is a meshless PCB autorouter program. Protel previously developed this module for its Protel 99 product, and has now adapted and added it to the P-CAD package. The new module is designed for automatic layout of multilayer printed circuit boards with high element density, especially using surface mount technology for element bodies made in different coordinate systems.

3.3 Automatic tracing

If there is no schematic diagram of the project, the components are placed in the work area of ​​the board using the Place | Component or by clicking the corresponding icon (Table 3). By command Place | Connection introduces electrical connections between component pins. This procedure can be carried out only in cases where the designed circuit is simple.

If you have a circuit diagram, use the Utils | Load Netlist, when executed, the netlist file is loaded (Figure 13).

Figure 13 - Loading a netlist file

Using the Netlist Format button, the required file for loading is selected, which contains information about the attributes of components and nets.

The following options are selected in this window:

- Optimize Nets - netlist optimization mode is enabled (disabled);

- Reconnect Cooper (Toggle Filling) - the mode of connecting metallization areas on the board to the circuits is on (off);

- Check for Cooper Sharing - mode for checking for errors on a board with pre-placed components;

- Merge Attributes (Favor Netlist) - merging the attributes of the netlist with the project attributes with priority given to the attributes from the list;

- Merge Attributes (Favor Design) - merging the attributes of the net list with the attributes of the project, with priority given to the attributes from the project;

- Replace Existing Net Classes - replacing existing net classes in the project;

- Ignore Netlist Net Classe - ignoring class definitions from the list;

- Ignore Netlist Attributes - ignoring netlist attributes;

- Replace Existing Attributes - replacing project attributes with attributes from the list.

After setting all the necessary parameters, the circuit is automatically packaged onto the printed circuit board (Figure 14).

Figure 14 - Result of packaging the circuit on the PCB

After packaging the circuit onto the board, they begin to place the components inside its circuit. Optimal placement of components determines the successful routing of conductors and the performance of the actual device.

The placement of components on the printed circuit board is done manually. Electrical connection lines that move with the components help to place the components correctly.

After placing the components, it is useful to minimize the lengths of the connections on the board by rearranging the components and their pins using the Utils | Optimize Nets. The window of this command is shown in Figure 15.

Figure 15 - Setting optimization parameters

In the command menu, select the optimization method:

- Auto - automatic optimization;

- Manual Gate Swap - rearrangement of equivalent sections of components manually;

- Manual Gate Swap - rearrangement of equivalent outputs manually.

When choosing automatic optimization, the following options are enabled:

- Gate Swap - rearrangement of sections;

- Pin Swap - rearrangement of pins;

- Entire Design - optimization of the entire project;

- Selected Objects - optimization of selected objects.

For automatic routing, you must select one of the tracers supplied with P-CAD. All tracers are launched from the RSV editor with the command Route | Autorouters (Tracing | Autorouters). In the Route Autorouters window that appears, one of the available routers is selected from the Autorouter list. (The QuickRoute router was chosen to do this job.) The tracer launch window is shown in Figure 16.

Figure 16 - Launching the tracer

At the top of the dialog box there are buttons that allow you to select or specify a tracing strategy (rules) file. By default, the names of these files are the same as the project name, the last two names are prefixed with R.

The Error Messages group specifies the direction of the trace log output.

Output to Screen - output to the screen;

Output to Log File - output to a log file;

Output to Both - output to the screen and to a protocol file;

Layers and Via Style call up standard PCB editor windows to set layers and their properties.

The routing strategy comes down to setting the grid spacing, setting the width of the wires, the default via style, and selecting routing passes. The grid step is selected in the Routing Grid window, the line width is set in the Line Width window.

The Passes button opens the Pass Selection menu of tracing algorithms (passes), in which one or more tracing algorithms are selected (Figure 17).

Figure 17 - Selecting routing passes

The passes are applied in the order they are listed.

- Wide Line Routing (tracing wide lines);

- Vertical (Vertical) - making simple vertical connections on any layer without using vias and with minimal deviation from straight lines;

- Horizontal (Horizontal) - making simple connections horizontally on any layer without using vias and with minimal deviation from straight lines;

- `L" Routes (1 via) (L-shaped routing with one via) - the formation of a section of the route consisting of vertical and horizontal fragments located on different layers and connected by one via;

- `Z" Routes (2 vias) (Z - shaped routing with two vias) - formation of an intersection of three conductors with two vias, shaped like Z;

- `C" Routes (2 vias) - forming a C-shaped intersection of three conductors with two vias;

- Any Node (2 vias) - similar to the previous three;

- Maze Routes (Maze Routes) - routing that can find a path for the optimal laying of the conductor, if this is physically possible;

- Any Node (maze) - a labyrinth routing is used, but for the largest number of connections, the conductors may not necessarily be laid in an optimal way;

- Route Cleanup - a pass to improve the appearance of the software and its manufacturability;

- Via Minimization - minimizes the number of vias.

After setting the necessary parameters and options to launch the automatic tracer, you must click Start. The tracing result is shown in Figure 18.

Figure 18 - Result of PP tracing

If, after designing, there are still unrouted conductors on the board, it is necessary to make a manual adjustment and re-route.

Using the Route | View Log (Trace | View report) displays the trace log.

3.4 Checking the printed circuit board for errors

Before completing the PCB design, you must use the Utils | DRC (Design Rule Check) checks the PCB for compliance with the circuit diagram and compliance with permissible technological clearances. In this menu, the window of which is shown in Figure 20, select the following check rules:

1) Netlist Compare - comparison of the list of connections of the current printed circuit board with a circuit diagram or another board, the list of connections of which is specified upon additional request;

2) Netlist Violations - checking the compliance of the electrical connections of the conductors of the current board with the original list of electrical connections of the project. When performing checks, objects are considered physically connected if they overlap each other or the gap between them is zero;

3) Unrouted Nets - unrouted chains;

4) Clearance Violations - violation of gaps;

5) Text Violations - violation of gaps between text located on signal layers and metallized objects;

6) Silk Screen Violations - violation of the gaps between contact pads or vias and silk-screen printing;

7) Unconnected Pins - unconnected pins

8) Copper Pour Violations - the presence of isolated areas of metallization, violation of the gaps of contact pads with thermal barriers;

9) Drilling Violations - checking the correct drilling of pins, through and blind vias;

10) Plane Violations - detection of metallization areas superimposed on each other, incorrect connection of pads and vias to them, isolated areas on metallization layers.

11)

Figure 19 - Checking the software for errors

4. Circuit modeling

4.1 General information about the modeling process in P-CAD 2004

P-CAD 2004 uses the simulation module (Simulator) of the Altium Designer 2004 (Protel 2004) system. When modeling analog devices, SPICE 3f5 algorithms are used. When modeling digital devices, the XSPICE algorithm is used with a description of models of digital elements in the Digital SimCode language.

The schematic diagram of the simulated device is created using the P-CAD Schematic circuit editor. When you select the modeling mode in P-CAD Schematic, data about the circuit diagram is automatically transferred in the form of a netlist to the control shell of the Designer system for drawing up a modeling task, the actual modeling and viewing its results. The main problem in modeling is the development of models of radioelements, especially domestic ones, since the accuracy of constructing the model determines the adequacy of the modeling.

With the powerful Mixed-Signal Circuit Simulator, you can perform a variety of circuit design simulations in P-CAD Shematic.

The simulation menu consists of two commands: Run and Setup, which allow you to control the simulation directly in the project after the analysis criteria have been set.

To perform simulation, all parts contained within a project must be modelable, that is, have simulation models associated with them. A project containing non-modelable parts will not be modeled. Instead, an error log will be produced showing any errors that prevent the design simulation from being completed. To check whether a component has a modeling model associated with it, use the Library Index Spreadsheet.

If the Simulate > Run command is selected, the simulation process will run immediately. If the Simulate > Setup command was selected, the Analyzes Setup window will appear, which allows you to set the study criteria (Figure 20)

Figure 20 - Setting simulation parameters

Criteria that can be set:

- Operating Point Analysis - calculation of the DC operating mode (calculation of the “operating point”) when linearizing models of nonlinear components;

- Transient/Fourier Analysis - analysis of transient processes and spectral analysis

- DC Sweep Analysis - calculation of DC mode when varying one or two sources of DC voltage or current;

- AC Small Signal Analysis - frequency analysis in small signal mode (for nonlinear circuits it is performed in linearized mode in the vicinity of the DC operating point);

- Noise, Pole-Zero Analysis - calculation of the spectral density of internal noise;

- Transfer Function Analysis - calculation of transfer functions in small signal mode

- Temperature Sweep Analysis - temperature change mode

- Parameter Sweep and Monte Carlo Analysis - changing the parameters of elements and statistical analysis using the Monte Carlo method.

Modeling an electrical circuit diagram of an electronic device created in the PCAD Schematic circuit editor can be carried out after a number of preparatory operations:

1) Components that do not have mathematical models (connectors, switching elements, etc.) are excluded from the diagram.

2) It is recommended to exclude from the diagram functional units that do not directly affect the simulation results, or such functional units that can be replaced with sources of signals and constant voltages and currents (for example, clock generators, power supply voltage sources and stabilizers, etc.) . Eliminating such functional units can significantly reduce circuit simulation time.

3) If necessary, external switching circuits of the circuit are added (elements connected to the connectors when checking the circuit, etc.).

4) It is necessary to add power supplies and sources that generate input signals to the circuit, and also set the necessary parameters of these sources.

5) The ground circuit must be given the standard name GND.

6) Power supply circuits of digital microcircuits must be assigned standard names (usually VCC, VDD), which must correspond to the names of the power pins in the components of the microcircuits.

7) In the properties of passive components of the circuit (resistors, capacitors, etc.) on the “Symbol” tab, the nominal values ​​of the parameters of these components are adjusted or set (“Value” parameter). All passive circuit components must be rated for their parameters. All active circuit components must have simulation attributes belonging to the Simulation attribute category.

8) It is necessary to ensure the availability of files of mathematical models of all components used in the circuit, the attributes of which contain links to such files. Model files must be located in the directories specified in the “SimFile” attributes of these components.

9) It is recommended to assign unique names to the circuits that are included in those nodes, the signals in which need to be visually assessed after modeling, for ease of reference to them.

After preparing the circuit for simulation, it is recommended to pre-check it by selecting the “Utils > Generate Netlist” command in the PCAD editor and generating a netlist in XSpice format. If errors were made during the preparation of the circuit, then when generating the netlist, a list of these errors is displayed on the screen and placed in a file<имя проекта>.ERR. This check monitors errors such as “the model file was not found for the component”, “there is no circuit named GND in the circuit”, etc.

To set supply voltages, currents and input signals, both constant and time-varying, in the simulated circuit, special components are used that describe sources of constant and alternating voltages and currents. These components are found in the standard libraries supplied with P-CAD. Sources of voltages and currents of a simple standard form (constant, periodic pulse, sinusoidal form), as well as sources of voltages and currents of arbitrary shape (specified by piecewise linear approximation), are located in the Simulation Source.lib library.

Modeling of circuit circuits in P-CAD with complex shapes, such as pulse trains, variable-frequency sinusoidal signals, variable-period rectangular pulse trains, triangular and sawtooth signals, etc., uses special components and combinations of these components and sources of simple form signals.

All voltage and current sources have the positional designation “Ref Des” U. The parameters of signal sources are set using attributes by adjusting their parameters in the component properties. Attribute sets are determined by the built-in system models of these components, so adding or removing any attributes in signal source components is prohibited (unfortunately, P-CAD allows this). It is also not acceptable to change attribute parameter names.

When the simulation process in a project is first started, unset study settings in the Analyzes Setup window will be used by default. After modeling, the project will be saved in a file with the extension .PrjPcb. When any changes are made in the Analyzes Setup window, they are saved in the project file (when saved) and are subsequently referenced in the simulation to the modified project.

A Spice netlist created from a schematic document does not contain any information. When the modeling process is started, the defined research settings are combined with the schematic-generated netlist to make changes to the Spice netlist (DesignName_tmp.nsx). It is this netlist file that is transferred to the simulator.

When the simulation process is started, a simulation data file will be generated (DesignName_tmp.sdf) and opened in the active Design Explorer window. The simulation result will be displayed in the Waveform Analysis window as a series of tabs (Figure 21).

Figure 21 - Simulation result

If the Design Explorer (DE) project file does not exist, it is created (in the same directory as the .sch and .nsx files). If it exists, the netlist file is generated again and the data is replaced.

The Projects panel shows each open project and its constituent files. The generated netlist appears in the panel under the Mixed Sim Netlist Files subfolder. The modified netlist (a combination of the netlist and the installed research information) appears in the Generated Mixed Sim Netlist Files subfolder. The simulation result is stored in a file with the extension .sdf and appears in the Generated SimView Data Files subfolder

The path for the produced files (DesignName_tmp.nsx and DesignName_tmp.sdf) is set in the Options tab (Options for Project dialog). By default, the path specified in the program is installed, but if necessary it can be replaced.

Before running a simulation, you must select which studies will be performed, the signals for which data will be collected, and which waveforms will be automatically displayed when the simulation ends. All of these options are defined in the Analysis Setup window. Each analysis type is displayed on its own window page.

Only one simulation can be controlled at any time. If the simulation is running in DE, and you try to control the simulation from a P-CAD schematic for the same or a different project, a message will be issued stating that the client is busy, you must try again later.

It is also possible to generate a netlist from a schematic design using the Utils > Generate Netlist command. Then you can freely open the netlist in DE and manage the simulation at a later stage.

It is possible to edit a netlist file directly in DE using the Text Editor. This is especially important if you need to make a replacement without going back to the circuit design (for example, to change the value of a resistor). The netlist used by the modulator is always *_tmp.nsx. If you edit it directly, it will be used immediately. If you edit the original (circuit-produced) netlist, then *_tmp.nsx will be restored, overwriting the one that currently exists. If you make changes to the schematic .nsx file produced, you must save it under a different name, otherwise it will be overwritten the next time the netlist is produced from the schematic document.

The settings that must be defined for each element of the modeled part are indicated in the Part Properties window on the Attributes tab (Figure 22).

Figure 22 - Window for setting the attributes of the modeled element

These settings include:

SimType- in a component ready for modeling, the first modeling attribute, which is described on the Attributes tab of the Properties window.

The Value field of this attribute must contain the following information: the type of device that is to be modeled and its SPICE designator prefix.

Syntax: ()

The device type and tag prefix must follow standard SPICE convention.

SimModel- in a component ready for modeling, the second attribute of modeling, which is described on the Attributes tab of the Properties window.

The Value field of this attribute must contain the following information: The component model name.

Syntax:

If the string " " is entered in the Value attribute field, the value of the component type on the Symbol tab is automatically assigned as the model name.

Component types such as resistor, capacitance, inductor, and sources that are internally defined and modeled in SPICE do not need to be entered in this field.

Digital devices use a simulation file to call a digital Sim code file.

SimFile- in a component ready for modeling, the third attribute of modeling, which is described on the Attributes tab of the Properties window.

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