I am working on a project that involves intel edison compute module inserted into a custom made board. During power up, at times i see that Edison is getting stuck on "Starting Kernel ..." or sometimes it loops on "Ready to receive application". This is getting more and more frequent nowadays. The following are the details:
kernel version: 3.10.17-poky-edison+
Power : Battery 3.8V or power supply unit 3.9V, 0.70A
Is this because of not properly powering off the processor? In our application, we have to power cycle the device more often. We cant really find a root cause to this issue. Also how can i reflash the Edison with the same image?
Please help ASAP. Expecting your valuable reply.
Thanks for reaching out!
I believe the issue is being caused by the battery not providing enough power to the board. I have seen similar behaviors using the mini breakout board on a PC that had USB port that were not able to provide enough power to the board.
The following is an extract of the Intel® Edison Breakout Board Hardware Guide ( http://www.intel.com/content/www/us/en/support/boards-and-kits/000005574.html):
"...Intel® Edison is a low-power device. In general, it does not draw more than 200 mA with 600 mA short duration spikes during Wi-Fi transmit..."
Since you are using a custom made board the closest thing I can compare it with is the mini breakout board, that why I quoted the document above. As you can see the board itself can consume up to ~600mA, this is very close to your battery's limit of 700mA and I suppose this changes depending on the charge. If you add this to any peripheral connected to the battery or the Edison, you'll see that it makes that the battery might not be providing enough power.
So, my best suggestion at this moment is that try using a different battery with more capacity. Try that and let us know how it goes.
I tested with a 4v, 1600maH battery. But i noticed that it got stuck once in "Starting Kernel...". Are you guys sure that this is a hardware issue? If it is, then which are the input lines to Edison that need to be probed ? So that we can make sure that Edison is getting the desired voltage levels.
I can't be sure that the issue is caused by the hardware as I don't have access to your design or the board itself, nevertheless, as I mentioned in my previous post, the behavior you described indeed sounds like the board is lacking power. However, as you mentioned, this is just a possibility and other things could be causing it.
So, if you'd like to make sure whether or not the issue is caused by the hardware, you can do a very simple test. Get an Arduino expansion board or a mini breakout board and check if the board has the same behavior with it. Make sure the board is properly powered and if the behavior continues then the issue is related to the image and if the issue stops then the custom board is probably what's causing it.
If the issue persists, then this means that there might have been an issue with the image and we could try to recover it using the flashall method (https://communities.intel.com/docs/DOC-25154 https://communities.intel.com/docs/DOC-25154).
On the other hand, if the issue stopped, then the issue is still probably power. So, in that case, I would suggest you to check the power supply circuit used on the mini breakout board and follow the same configuration. You can find the schematics in http://www.intel.com/content/www/us/en/support/boards-and-kits/000005699.html.
Let me know how it goes.
Thanks for the detailed reply. Its seems to be a hardware issue as the issue is not persistent. Is it possible for you to review our schematics (the power section of Edison)? If yes, how can i send it to you? I dont see an option here to attach pdf.
Sure, if there is no problem sharing the schematics, I'll be glad to check them to see if I can find something unusual. There is actually an attach button but it is a little bit hidden. Check the screenshots below to learn how to attach files:
Once you share the schematics I'll analyze them and let you know if I'm able to find anything.
Adding some more findings here.
In our design, PWRBTN# is pulled up to 1.8V and not to 3.3V. Can this be a possible reason? Also we probed VBAT, it didnt drop while device got stuck.
I've been analyzing the schematics you shared with us. On first look everything seems fine, you are following the manufacturer's recommended schematization. Therefore I decided to compare the chip you used and the one used on the mini breakout board. The differences I focused on were the following:
TLV62090 ( http://www.ti.com/lit/ds/symlink/tlv62090.pdf):
Vout= 0.8v – Vin
Chip Vin range: 2.5v – 5.5v
TPS62133 ( http://www.ti.com/lit/ds/symlink/tps62133.pdf):
Vout: 0.9v - 0.6v
Chip Vin range: 3v – 17v
Then, I looked at the schematics of the mini breakout board and noticed that the chip is configured to provide 5v, this signal powers the BQ24074 ( http://www.ti.com/lit/ds/symlink/bq24074.pdf) which is the battery charger. This IC then creates the V_SYS signal which has a range of 3.15v < V_SYS < 4.4v according to the schematic.
Looking at your design, I noticed that your output is set to 3.3v, which is on the range of operation of V_SYS and should be fine. Nevertheless, I decided to check how the output voltage is set on the TLV62090, I found on section 188.8.131.52 of its datasheet that it is given by a formula, I according to my calculations, it is indeed set to 3.3v.
Anyhow, I would like you to confirm that indeed you are receiving this output. Right now, I believe this is our best lead and in case for some reason one of the resistances that define this voltage is damaged, this could cause this behavior.
Let me know.
Thanks for your analysis of the schematic. Meanwhile we did some reworks on the board and now it seems the bootup issue is resolved. We connected the PWRBTN# pin to VBAT (3.6V). Earlier this pin was connected to 1.8V.
Thank you for letting us know how you managed to fix the issue. We're glad to hear that this behavior is no longer present.
If you ever have any other doubts or issues, please don't hesitate to come back to the community, we will be more than glad to assist you.