florent243
Posts: 4
Joined: Wed Aug 13, 2014 2:59 pm

Compute module won't boot

Wed Aug 13, 2014 3:28 pm

Hi,

I've just receive my compute module recently, and i've made a PCB for this.
On this PCB, i've put a usb HUB 2.0 with a wifi chip and an audio chip.

When i've put cable to connect the hub and the raspberry compute module development board, all work well, i can acces the raspberry by ssh !

But when i plug the raspberry compute module in the DDR2 slot, of my own pcb, it seems like he is not running..

I've put,
GPIO-VREF (Pins 39,40,41,42) VBAT and 3v3 (Pins 200,199,197,198,194,193,192,191) to 3V3 (decoupling supply)
1V8 (Pins 183,184,185,186) to 1V8 (decoupling supply)
EMMC_DISABLE_N (pin 2) to 3V3
GPIO47_1V8 to a led and the led to the ground (in the right direction without resistor ) and she don't do anything.
RUN (pin 177) is floating

For the usb, DP0 and DM0 are directly connected to the hub without resistors or capacitors.

Where do you think i've missed something ? :/

Thanks for your help !

PS: supply can delivery 3A

grp62
Posts: 32
Joined: Fri May 23, 2014 7:41 am
Location: Lyon, FR

Re: Compute module won't boot

Wed Aug 13, 2014 5:08 pm

Hi florent,
Did you check the power sequencing ?
What image did you flash on the CM ?
Do you have a console available on a serial port and/or HDMI output ?
Greg

florent243
Posts: 4
Joined: Wed Aug 13, 2014 2:59 pm

Re: Compute module won't boot

Thu Aug 14, 2014 7:56 am

Hi,
what do you mean with power sequencing ? I've check all the supply, and they are all okay..

I've flash raspbian, and all works well when I plug the module in the development card and I put an usb cable between my pcb and the development card :/

On my own PCB, I haven't put an hdmi output unfortunately, but when I turn on and I put the RUN pin to the ground, there is a little drop of current, and when I remove it, I have an increase of current.

It seems like the module is started, right ?

Thanks

User avatar
rpdom
Posts: 16312
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Compute module won't boot

Thu Aug 14, 2014 9:40 am

florent243 wrote:what do you mean with power sequencing ?
If you check the specs for the CM, the power rails are supposed to be started in a certain order with a very slight delay between each one, or possibly all activated at exactly the same time (but timing is critcal for that). If they come up in the wrong order the SoC may have trouble starting.

Looking at the CMIO board schematics, there is a small RC delay built in to one of the regulator circuits.

florent243
Posts: 4
Joined: Wed Aug 13, 2014 2:59 pm

Re: Compute module won't boot

Thu Aug 14, 2014 12:47 pm

Oh okay ! I'll try that !

florent243
Posts: 4
Joined: Wed Aug 13, 2014 2:59 pm

Re: Compute module won't boot

Thu Aug 14, 2014 2:42 pm

I've tried to put a RC filter to add a delay on the 3V3 lines but nothing :/

Briarios
Posts: 119
Joined: Thu Feb 21, 2013 11:35 am
Location: Perth, Western Australia
Contact: Website

Re: Compute module won't boot

Thu Aug 14, 2014 10:10 pm

assuming that you only have 3v3 and 1v8 lines connected, you will need to delay the 1v8 lines on the CM in order for it to boot.

read http://www.raspberrypi.org/documentatio ... gnguide.md
http://rpi.pmfg.me -- Test board Eagle Cad Files.

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