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Further Analysis Protel DXP's Circuit Schematic Diagram

Further Analysis Protel DXP's Circuit Schematic Diagram

Jan 20, 2018

1  Design of circuit schematic diagram

The design of the circuit schematic diagram is mainly to draw a circuit schematic diagram by using the principle diagram of Protel DXP to design the system. The feature is that the drawing precision is high, because its smallest unit of drawing is a milli inch. In the drawing process, make full use of the Protel DXP provides a variety of principle drawing tools and various editing functions, including the common drawing tools with wire tools and drawing tools, should pay attention to the difference between them, master these can be drawn a correct and fine circuit principle diagram. There are several ways to enter the element, in Input the element serial number in the Designator bar, input the component mark in the "Part Type" column, and the element package type in the Footprint bar can be temporarily input, because it does not affect the design of the circuit schematic diagram. In addition, you can click the "place" in the device manager to place or use the menu "place" to place various electrical objects.


First, to place the element on the schematic, it must first be loaded into the component library. The system has the common components in advance into the library, it is the name of the path of programfile\altium\library\Miscellaneous Devices.intlib, because Protel is a professional circuit design software for electronic design of the professional staff and the majority of electronic enthusiasts, the parts library contains components for the symbol diagram is quite comprehensive, so many parts of the number of parts library. I do not know the number more, so that beginners to which parts library to find the required components. Beginners generally only need to load the "Miscellaneous Devices.lib", "Protel Dos.lib" two component libraries, basically enough.


Second, learn to find the "element symbol name" corresponding to the component in the component library. The discrete components can generally be found from the graphical symbol library "Miscellaneous Devices.lib" provided by the software, which is more intuitive and clearer. Some common components can also be placed in the component library of their own, so it is more convenient to find the components.


Third, in the process of drawing the schematic, we must pay attention to the drawing method of the wire. This part is prone to make two mistakes. One is to use line (Line) instead of traverse (Wire). The difference between them is the default color is different, one is light blue, the other is dark blue. The key is that the line can not conduct electricity, and the conductor can conduct electricity, which is of electrical significance. The starting point and end point wire should be endpoint and component pins coincide, even from the circuit principle diagram on the surface without error, and in fact after the electrical inspection rules will appear in the circuit diagram with the wrong identification, marking that connecting wires is wrong.



2  Making components

Protel powerful DXP is also reflected in the production of components, we in the drawing process, often encounter such problems, not the component pin position of some components is unreasonable or provided by the system component library, an electrical diagram such as drawing principle diagram in environment, but the basic components normally open and normally closed that there is no ready coil. This requires that we first draw these electrical components, and then in the drawing.


The system provides a powerful component editor. For we can make some components, but in the process of drawing components should pay attention to some problems, the first is the components and principle diagram of package library components are not the same, in addition to draw all kinds of chips, a component may contain multiple components, don't leave when drawing. Second is to draw electrical components, there are three modes, with 74LS00 as an example, the standard mode Normal, the di Morgan mode De-Morgan and IEEE mode. For these three patterns, we usually use the pattern: Normal, but the other two must be drawn when the component diagram is drawn. 74LS00 is a 4-2 NAND gate, there are four components to draw attention to the pin number and arrangement of the power and ground pins hidden drawing.


3  Generating network tables

The network marking schematic is a bridge between SCH and PCB. If the beginner has no experience in drawing circuit boards, it is necessary to get a network table from the schematic diagram of the circuit. It is the soul of the automatic circuit board. In this section, you should learn to read the network table. The network table consists of two parts: the component declaration part and the network definition section. How to modify the encapsulation of the components in the network table, the component encapsulation in the edit position in the network table, etc. It is a headache for many people to check the correctness of the network table. One of the important reasons is that the network name in the network table cannot be read directly on the schematic diagram. The way to solve this problem is to place simple network labels on each network of the schematic diagram. There are two purposes for network marking: first, make the bus or other network easy to identify; first, express the electrical connection. For the same schematic diagram, a network with the same number of networks indicates that they are all connected together.


4  Design of printed circuit board

The design of printed circuit boards is an important part of Protel DXP. In general, if ERC is used to make PCB, the inspection of electrical rules must be done before making PCB. Otherwise it will add a lot of circuit board repair work, need to hand drawn copper wire, plate design we use the powerful Protel DXP provides the realization of circuit board.


Protel software is deeply loved by electronic enthusiasts. It is generally considered to be simple, but this simple and easy use is the operation of software itself, and the professional knowledge of PCB involved in it is more difficult for beginners. Here, the focus of teaching is on how to place the type of component encapsulation, transfer to the network table, and automatically generate the PCB diagram. The steps are as follows: designing schematic diagram, planning circuit board, setting parameters, introducing network table, automatic layout and manual adjustment of components, wiring rule setting, automatic wiring and manual adjustment, report output, save and print.