Author Topic: Multi-channel design harness use  (Read 830 times)

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Offline ANTALIFETopic starter

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Multi-channel design harness use
« on: May 12, 2023, 12:37:28 pm »
Hey All

So I have an Altium project where I reuse a single schematic a few times (RGB LED driver), to which I interface via a single harness. To make the situation tricky I also use a different harness name & net label depending if it's going to the front or rear RGB LEDs. For example, net LED-RGB-CH1-PWM on harness LED-RGB is connected to either:
  • net LED-RGB-CH1-PWM-FRNT on harness LED-RGB-FRNT
  • net LED-RGB-CH1-PWM-REAR on harness LED-RGB-REAR

As you would expect Altium gives me a bunch of "Multiple Harness Types" & "Nets Wire X has multiple names" warnings during PRJ compile, but when I sync up PCB to SCH these surprisingly solve themselves as net LED-RGB-CH1-PWM becomes:
  • LED-RGB-CH1-PWM_1 for front RGB LEDs
  • LED-RGB-CH1-PWM_2 for rear RGB LEDs

BUT this use of harnesses in a multi-channel design still feels wrong... So what would yous recommend I change to solve the PRJ compilation errors?

Also below is the Altium project, and I tend to get mixed up with terminology... so let me know if something is wrong
https://drive.google.com/file/d/1zq5Rk8K2PCpuXRSkb8abxbrne0hsyhdf

Offline ajb

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Re: Multi-channel design harness use
« Reply #1 on: May 12, 2023, 04:10:38 pm »
Why the different harness types for front vs rear if all of the signals are the same?  Harness types should be consistent through harness connectors and ports.  If you need to differentiate harnesses of the same type by function that can be done by the port name or other annotations.  Setting all of your ports and harness connectors to the same "LED RGB" harness type will get rid of the multiple harness types warning.

The "Net has multiple names" warning is basically inevitable with multisheet designs especially with harnesses or busses in the mix, I just turn that warning off since it's just noise and doesn't really help with validating connectivity. 

As for the names the nets end up with after compilation, that depends on your project configuration.  Unfortunately there are a ton of possible combinations of options and it's not always clear how they will interact with each other or with harnesses, so if you want those nets to end up with different compiled names it will probably just take some trial and error. 

As a more general note, are those really long net names in the net labels really necessary? One of the benefits of multisheet design (especially with harnesses) is that you don't have to create long, specific net names like that, but instead can use shorter local net labels within sheets and allow the compiler to resolve them to suitable project-wide names based on your project settings. 
 


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