Im currently working on a research board to carry a CM3 with an IMX219 camera on it.
This is pretty handy, as you can have a small package with everything requiered.
Still Im running into several questions, related to hardware, as I'm new to this:
- Im not sure if the high speed routing of the CSI2 bus can be done on a 2-layer PCB - I found several sources, some are telling me, that a 4-layer PCB is needed. Any thoughts here?
- Also the routing is a question - should all lanes (I'm going for 2 lanes) be exactly the very same length? And if yes, can they switch sides with a via? I have them about 16,1mm long, but one diff pair is 16,0442mm and the other one 16.136mm...
- Is the routing impedance of 100R ment for Odd, Even, Common or Differential Z?
- Is it okay to share the same power supply with the IMX219 (talking of 1.8V digital supply, not 3.3V)?
- I saw the Pi Cam 2 having some Common mode chokes on the bus, but also reading, that this is not recommended - any idea why?
If someone could help me a bit, I would be very happy. Also just ideas or explenations are welcome!
Thank you and regards