FunGuy
Posts: 8
Joined: Sat Jan 06, 2018 10:11 am

Bare minimum - Compute module startup

Wed Dec 11, 2019 6:55 am

Hi Everyone,

I have been working on a compute module 3 development board the last few weeks and wanted to create my own PCB. However, since then I have run into a few problems. After many debug sessions I have fixed most of my support circuitry. However, I am having a lot of difficulty booting my compute module on my board.

So what I have is the CM3 development board which boots my CM3 and upon startup blinks an LED on GPIO14. It works perfectly. I then have my custom made PCB development board with only the bare essentials to boot the CM3. I have eventually resorted to the simple schematic (as shown in this post) and to power my board from the CM3 development board (ensure proper power boot sequences). I have checked all the power lines and several other things with no success in finding the mistake. It seems that for some reason the CM3 keeps rebooting on my board.

Can someone please have a look at my schematic and tell me if I have done something wrong? It is the bare essentials to only boot the CM3 and to blink LED on GPIO14. Power is supplied to my custom board from CM3 development board.

Thanks for all your help in advance!
Attachments
CM3DevBoard.png
Bare Essentials
CM3DevBoard.png (62.96 KiB) Viewed 671 times

nomdediot
Posts: 52
Joined: Sat Feb 02, 2013 3:04 pm

Re: Bare minimum - Compute module startup

Fri Jan 03, 2020 10:59 am

I m doing the same job, I see you are using kicad too!

Difference with my board I can are only:
- VBAT supply, I m using 5v like on the cmio. However the data sheet indicates should run with 3.3v so OK probably but maybe you can check with 5v?
- emmc disable circuit not present at all on your schematic, not sure it s important

I have previously experimented many problems to boot with some crash of the kernel on startup or some partition errors on the emmc. See https://www.raspberrypi.org/forums/view ... 8&t=260400. The problem was the power consumption of the module on startup, my supply was not able to provide enough current. I just changed the supply and every thing was great then.


Which kind of power supply are you using?

Do you have boot logs?

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