Code Corrupted after full discharge of batteries, upon reboot. NRF51822 SDK 12.3

[Robin]

Hello Nordic Wizards,

We are in the final throws of a project preparing to go to market.  However we have identified a "strange" problem.

if the batteries driving the board power are allowed to fully discharge, once they start recharging, plugging/unplugging the board from a charger resets the board and may lock the code up in an unknown state.  If the board is reprogrammed, this condition stops, until the next time the battery/board is fully discharged.  Has anyone see these types of problems with this chip, and/or can you point me to a prospective solution.

Thank you kindly

Robin @ TL

[daviddedwin]

The tools are usually installed in "Program Files (x86)\Nordic Semiconductor\nrf-command-line-tools\bin" 

[Kenneth]

Here is a snippet from the spec:

Based on your current description I am not quite able to understand what may be causing your problems here, are you able to share schematic of the design? It is possible that the nRF51 is actually starting running code, but it stops during initialization due to code is waiting for something (e.g. external sensors), can you add a LED blink on the start of main() to check for this?

Can you share a plot of VDD when it starts to charge? I just want to check if there is something we are missing here. 

Robin said:

3.) After adding the pulldown to the nRESET pin, there is a change is symptoms.  The chip will not reboot and run even after a board power reset.  It only runs after a reprogram.

 And you can confirm it is a 1Mohm, and not for instance a 1kohm?

[Robin]

Hello again Kenneth,

I could send you a plot of VDD rise and fall, but I will for now ask that you believe me.  The rise is <300uS, the fall is > 100mS.  I will send you the schematic, and those plots when I get down to the system later today, but first I will need to change this case to private, if I can remember how.

The resistor is indeed very high value, but not exactly 1 Megohm. 

The symptom I mentioned, I have found to be somwwhat erratic, ie sometime appears and others not.  The only consistent symptom is that after a discharge, when plugging the board into a charger, the code freezes.  Sometimes it restarts when unplugged, other times it does not. 

Right now, what I am most concerned with, is whether or not I have the chip properly configured for Low Voltage mode at the voltages the board is designed to use, and whether I need to write any code to insure a safe power down.  Again, can you please enumerate the firmware requirements to do so?

Thanks ad nauseam,

Robin @ TL 

[Robin]

Hello David,

Interesting, they are there, but the program wont run from command line.  Probably a pathing issue.

Thanks again

Robin @ TL 

[Robin]

Hello again Kenneth,

I cannot insert these graphs of VDD Rise and Fall.  This page says they are unallowed.  How can I get them to you?

Robin @ TL