Keyword: pcb design, PCB copy board, PCB design techniques
There are many skills about PCB copy board online, PCB design techniques articles, pcb board mostly to teach people how to avoid interference, how to take the ground , and so , in fact, PCB copy board software there is also a feature that is very useful , and this is NetClass functions. PCB netlist file loaded for the first time , do not be classified . This function can be manually categorized numerous network connections , such as sharing power, data_bus, Address_bus, Hi_volta categories such as copy board .
Such classification can be applied separately for different categories of different PCB Layout routing strategy . Okay, now let's try this feature ( in protel example ) : First, open a PCB schematic ; selection menu "Design -> Classes .." pcb board jump out of the screen in Figure 1 . Here I have pre- set a good few C, where "AllNets" is protel default class that contains all of the networks. If you define routing rules , the default is to copy board for this category . Now I want to add a pcb board this means that the CPU address bus category "Address_bus", drawing a screen press "Add" button , the screen in Figure 2, the input select "A0 ~ A 19", then select " > " of these networks to the right and the sub-window . Shown in Figure 3 . This establishes a new good pcb board network category. Using the same approach PCB copy board, then create "power", "data_bus" and other network types .
Well, we were designated for these network categories wiring strategy right , we first specify the routing strategy for the power class . Figure 4 screen press "Add" button to copy board , adding a strategy . Shown in Figure 5 , "FilterKind" Select "NetClass", "NetClass" Select "POWER", and its width can be set separately parameters, you can also add a near limit POWER class rule ( as my is a 4-layer printed circuit board , and I do not set this project is close to the rules ) pcb board. CPU external bus frequency of about 200MHz copy board . So the address bus and data bus design becomes critical . Each address bus length difference between not too long, otherwise it will cause transmission delay . But the hand to measure the length difference is trouble , here you can set up an address bus that wiring rules pcb board. In Figure 6, copy board wiring rules window , select "LengthConstraint", the pop-up window in Figure 7 , select "ADDRESS_BUS" category , you can set the minimum and maximum length of the bus length copy board . Figure 8 shows the window can be set up for this NetClass serpentine routing rules .
After setting the above rules PCB copy board , either manually or automatically routing the wiring will be much simpler . In the manual wiring and trimming circuit board in the process, do not have to consider these arguments , because you foul , PCB copy board editor will give a warning . With this setting copy board, you can a lot of time signal line rule ,pcb board no longer need a separate set up a signal . Can save you a lot of time to copy board, you can avoid a lot of low-level errors should not commit pcb board.
