Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 12:56 am

Hi,
we made a custom board for a industrial product using the Compute Module 3 lite.

First revision worked beautifully. We then made a couple of tiny mods (just resistor values to the display bias voltage) and made a new series of boards and the new boards are not booting up. Or to be precise when booting up:
- one of the boards's boot LED turns on steady (i.e. no flashing) for maybe a second then it permanently remains off
- on another it it turns on steady for 1 second then off then remains permanently on steady (i.e. no flashing). Sometime it does remain off instead of turning back on but most of the time when it comes back on it remains on steady

What can it be?

We change the CM and also alternated various between the old boards and the new boards and when placed in the old PCBs it works. So it cannot be damaged CMs.
We changed several times the uSD card back and forth between the old PCBs and the new ones and it is working when placed in the old PCBs, so it cannot be a damaged uSD or OS.

Why does the LED come on for 1 second then off? What does it mean?

Most importantly, what can it be and how can we debug it?

Many thanks
Rick

aBUGSworstnightmare
Posts: 1075
Joined: Tue Jun 30, 2015 1:35 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 4:56 am

Hi Rick,

Sorry to say, but there is no LED on a Compute Module, so nobody will be able to give an answer without knowing your carrier board schematics!

You mention changes in LCD bias, so is my assumption correct that your display is on DPI? No other changes to the board?

gsh
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Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 6:12 am

https://github.com/raspberrypi/document ... /bootmodes

Use a serial cable to debug why it is not booting, if the LED is going out this means it is definitely booting bootcode.bin but not getting any further...

Gordon
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 2:29 pm

To all,
I just tried attaching a PPT and PDF showing the summary of all changes but it does not allow me to attach it...?!
I also tried drag and drop but nothing...
It says "Invalid file extension: Summary of changes.pdf"...?
Any idea how I can attach files?

aBUGSworstnightmare
Posts: 1075
Joined: Tue Jun 30, 2015 1:35 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 2:35 pm

Rick123 wrote:Any idea how I can attach files?
Always used a shared (read only) folder on Google drive.

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 2:51 pm

The LED I was referring to is the EMMC signal. See also schematic attached

Details of all the mods are in attached pictures.

Nothing seems it can affect the CM booting... But please do provide any feedback.

I also had a look at the link from Gordon but although I have experience in firmware development, I have practically none when it comes to the RaspPI/CM. Any other way to figure out what it could be?

Any suggestions from the schematics?

NOTE: I attached 6 schematic pictures but it shows only 3??

Many thanks to all!
Attachments
Slide2.PNG
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Slide1.PNG
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LED.png
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Last edited by Rick123 on Tue Aug 21, 2018 2:56 pm, edited 1 time in total.

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 2:55 pm

I attached 6 schematic pictures. They all showed in the preview but only 3 show now.

Also I tried reloading them and it does not let me....???

aBUGSworstnightmare
Posts: 1075
Joined: Tue Jun 30, 2015 1:35 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:01 pm

Rick123 wrote: I attached 6 schematic pictures. They all showed in the preview but only 3 show now.

Also I tried reloading them and it does not let me....???
Add them to another post.

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:06 pm

Remaining of schematics attached.
Thank you
Attachments
Slide5.PNG
Slide5.PNG (130.62 KiB) Viewed 609 times
Slide4.PNG
Slide4.PNG (208.84 KiB) Viewed 609 times
Slide3.PNG
Slide3.PNG (211.24 KiB) Viewed 609 times

aBUGSworstnightmare
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Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:16 pm

Rick123,
everything posted so far is just some secondary electronics (LCD related, second uSD Slot, etc).

Is your system booting when you just ommit all the secondary stuff (no LCD connected, no uSD inserted into second slot, etc)?

What is your approach for configuring RPi's GPIO to the required initial states (dave for your HW)? Have you created a custom dt-blob.bin for this or you you intent to use overlays i.e.?

aBUGSworstnightmare
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Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:18 pm

One note to VCOM (flicker adjustment): how do you want to cope with tolerances? Or is flicker simply initially set and not check during production?

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:39 pm

Yes exactly, all secondary electronics.

No, the behaviour remains the same whether I attach the display or not and whether I insert the secondary uSD card or not (we never used it anyway).

This is the behaviour summary across the two runs:

First proto (10 PCBs all worked well):
- LED ON for roughly 1 sec
- LED OFF for roughly 1 sec
- LED randomly flashing showing random access to the uSD card (i.e. like a PC hard drive)

Second production run (with mods outlined above):
- LED ON for roughly 1 sec
- LED OFF for roughly 1 sec
- LED remains off for some boards and for other boards it turns back on but remains steady ON (i.e. no flashing reflecting random uSD card access).

The main thing is that I move the same uSD card and the same CM Lite between V1 PCBs and V1.1 PCBs and the above happens. So it cannot be software related?

But to answer your question, no custom code (I have no CM software experience) apart from turning on the GPIO45 in a Python script after boot which enables the display BUT it never reaches that stage anyway.

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:40 pm

Ref the flicker we were not planning to check it in production. Why? If you have any suggestions, ideas or infos please do share. Always interested in improving a product/design!

Thank you

gsh
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Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 3:53 pm

Rick123 wrote:
Tue Aug 21, 2018 2:51 pm
I also had a look at the link from Gordon but although I have experience in firmware development, I have practically none when it comes to the RaspPI/CM. Any other way to figure out what it could be?
Just enable the UART boot and get the boot log out of the device. Then attach here and we'll be able to debug it...
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Tue Aug 21, 2018 4:12 pm

Is the boot log on the uSD card? If yes, where exactly?
if after switching off the previous boot log remains then I could just copy that file using a uSD card reader?

Also I am not sure what you mean by enabling the UART boot. I could not find anything on Goggle.
I remember when I first tested the first version of our PCB that I could connect to a PC via the USB cable and using some sort of terminal program. Is that what you refer to?
If so, where do I find infos how to do that (it has been almost a year since I did it)?

Thanks

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Wed Aug 22, 2018 1:07 am

With ref to my previous post could you please let me know about those points because after googling quite a bit I could not find any UART boot or anything similar (most likely I have been googling the wrong wording).

The only thing I came across was a post suggesting to install the rpi_boot tool. I did that and booted the PCB. All I got was:
- the CM device appearing in the device tree (see attached screenshot)
- the rpiboot window shows some basic infos as shown in the second screenshot. But in that windows I cannot input anything, it is just a output window.

Any clarification/help is appreciated.

Thanks
Rick
Attachments
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Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Wed Aug 22, 2018 2:46 pm

Hi Gordon (or someone else),
could you be so kind as to let me know about the above asap. We need to solve this issue asap because production is being held up by this PCB which is just a re-run of a previous fully tested one with no hardware changes which can affect the Compute Module yet the CM is what does not seem to work correctly.

If you could also look out for my posts to this thread would also be very much appreciated for the same reason as above.

Many thanks again! :)
R.

6by9
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Re: Compute module lite not booting (LED on then off)

Wed Aug 22, 2018 4:00 pm

Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
Please don't send PMs asking for support - use the forum.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 2:17 am

Thank you for that link, unfortunately got nowhere.

You link and the previous post mention a UART. We don't have any UART output in our Compute Module carrier board and we have no way to tap into any trace or pin reaching the UART IOs. Hence my previous questions left unanswered about using the uSD card instead (if possible?) and the request for clarification about the UART.

So in summary:
- we use a Compute Module LITE
- carrier board has the micro USB connectivity for a PC (i.e. the circuit is the exact copy of the reference/official CM IO board including the jumper enabling eMMC
- Ethernet connectivity
- no UART access whatsoever

I appreciate your help and understand you are busy, but could you please address each of the following separately and clearly because I spent the whole day and night (now 3 a.m.) trying to figure out things from the brief replies above and got nowhere. :)

Questions:
1. Is the boot log you requested to post here on the uSD card?
2. If after switching off the previous boot log remains then I could just copy that file using a uSD card reader? Or do I need to have real time connectivity to a PC?
3. in each of the cases where do I find the boot log?
4. I assume the boot log file name is actually bootlog? What extension?
5. The post you shared mentioned formatting the uSD card and installing ONLY the bootcode.bin. It didn't work and to be honest after seeing the tony size of that file I would not expect it to because there would not be any OS installed (i.e. again we are using the compute module LITE)

Could you please address each question separately and (because of my lack of knowledge of the PI platform) very clearly (rather than short quick links which would obviously assume a Pi knowledge that is not there :) ).

Once again thank you for your help :)

aBUGSworstnightmare
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Joined: Tue Jun 30, 2015 1:35 pm

Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 7:55 am

Rick123,
your LCD is connected to DPI Interface, right? Which Kind of connector is on your PCB (i.e. FFC connector)?

DPI_10 (=GPIO14) and DPI_11(=GPIO15) are the pins required for the UART. So it should be possible to debug.

gsh
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Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 8:23 am

Questions:
1. Is the boot log you requested to post here on the uSD card?
No, it is only output during the second stage booting process and only to UART. So it is not possible to debug with this
2. If after switching off the previous boot log remains then I could just copy that file using a uSD card reader? Or do I need to have real time connectivity to a PC?
N/A
3. in each of the cases where do I find the boot log?
N/A
4. I assume the boot log file name is actually bootlog? What extension?
N/A
5. The post you shared mentioned formatting the uSD card and installing ONLY the bootcode.bin. It didn't work and to be honest after seeing the tony size of that file I would not expect it to because there would not be any OS installed (i.e. again we are using the compute module LITE)
Actually, I was only referring to the enabling of the UART not bootcode.bin only booting.

Without UART there is no further debug available (other than the LED). If the LED is not flashing then it is not a standard error. Can you probe the EMMC_DISABLE_N line? It should be continuously high, is this the case? Even if you have the lite version the disable line will still disable communication with the SD card and force it to try booting from USB. Do you have access to the USB, can you connect this to a Raspberry Pi and see if enumerates (use lsusb to see if it appears)
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

gsh
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Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 8:24 am

aBUGSworstnightmare wrote:
Thu Aug 23, 2018 7:55 am
Rick123,
your LCD is connected to DPI Interface, right? Which Kind of connector is on your PCB (i.e. FFC connector)?

DPI_10 (=GPIO14) and DPI_11(=GPIO15) are the pins required for the UART. So it should be possible to debug.
Good point, you do have access to the UART...
--
Gordon Hollingworth PhD
Raspberry Pi - Director of Software Engineering

Rick123
Posts: 53
Joined: Fri Jul 21, 2017 6:53 pm

Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 2:43 pm

Thank you Gordon and aBUGSworstnightmare,

1. We wanted to use the DPI interface but apparently is software locked so you can only use it with the RaspPi display. We have a custom non-Pi display so we have to use the HDMI through two conversion chips. HDMI to TI's PanelBus then PanelBus to LVDS. So I will have to find another way to get to the UART. Is that the specific UART I need to use?

2. Once I do I assume then I will just connect it to a UART terminal like Putty and save the output dump? Is that what you mean by the boot log?

The part of the circuit using the EMMC_DISABLE_N line is very simple and exact copy from the reference design (see screenshot below). In all boards including the fully working batch regardless of the position of jumper J4 (in screenshot below) the EMMC_DISABLE_N remains always at 0.4V.

3. You mentioned it should be continuously high which sounds like that should be 3V3 or 1V8? Should it be to either of those voltages or is 0.4V correct?

4. Yes, I do have access to the USB. Sch copied from the reference CM IO board (see the attached schematic). See also screenshot of lsusb. Ran it twice, before and after connecting the CM. It looks like it sees it. Can we do any type of debugging from there or from the Ethernet (also available copied from the the Pi1 or Pi2 ref schematic?

Many thanks again to both of you! :)
Attachments
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Rick123
Posts: 53
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Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 2:43 pm

I cannot attach more than 3 images so below another screenshot from Windows device manager tree showing the CM connected via USB.
Attachments
2018-08-22_014949.png
2018-08-22_014949.png (6.68 KiB) Viewed 440 times

aBUGSworstnightmare
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Re: Compute module lite not booting (LED on then off)

Thu Aug 23, 2018 2:58 pm

to boot from uSD your Jumper on J4 Needs to be in 2-3 --> EMMC_DISABLE_N will be high --> boot from uSD.

If your EMMC_DISABLE_N remains LOW you should have a closer look at this particulary cuircuit dealing with this signal.

What happens if you have VSUSB=5V and J4 in 1-2pos?

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