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Zero-ohm for debugging question?

Mshakeri65 , 12-06-2017, 03:37 PM
Hi Robert,

I open iMX6 PCB project and the the first question that came to my mind was How to Debug It??
Because when we design a PCB project we use some "zero-ohm resistors" at main components power rail for probable problems and debugging, with these zero-ohm resistors we can disconnect any component from main power rail and if we don't place these zero-ohm resistors we have not any way to debug except desoldering main components!! with these zero-ohm resistor we have a new problem that the power plane will not a be a solid plane and have some split planes.
How do you handle any problem when you use a solid power plane? And if we use zero-ohm resistors how can we get the best solid plane and minimize the split planes? Is there a good and general guideline?

robertferanec , 12-07-2017, 10:58 AM
I open iMX6 PCB project and the the first question that came to my mind was How to Debug It??
For complex boards, debugging can be very limited. for example, debugging x86 boards is extremely difficult. So how to do it?

My answer is:
You have to be extra careful when creating schematic, layout and when assembling complex boards. When you build a complex board and you connect it to power, it just should work. There is not much space for errors or mistakes, because debugging complex boards takes a looooooooooooooot of time, it may cost a looooooooooooot of money and often you may not even find out what is wrong and better is trash the board or completely re-do the design.

About the 0R and power planes:
You still can use 0R and disconnect some peripherals also on complex boards, but your hw debugging is limited. For complex boards, there is always a lot of local power planes, so often we place them into the middle of PCB between two solid GND planes, or the other words, we do not use these power planes as reference planes.
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