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]

1. Please state the chip markings on the nRF51822
2. You should try this on an additional board if that is possible.
3. Read the flash on the chip after a failure to see if there is any difference before and after the condition occurs, the nrfjprog utility will help you read the chip flash.

[Robin]

Hello David,

I assume you are the assigned Nordic Engineer, No?  Anyway

The chips are marked "N51822/QFAAH3/1906EP.

The symptoms occur on all boards (10 each).

I will likely need some help using the nrfjprog utility.

One of our US field agents is suspicious of power circuit issues.  We are running the board/chip at 2.8V, with a precision 2.048V Ref applied to AIN0.   Can you please enumerate the settings I need to insure are correct for proper power management to occur?

Thank you kindly,

Robin @ TL

[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 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 

[Robin]

Kenneth,

Please make this case private, and I will share the schematic with you.  But so far your website will not let me upload any files.  What the secret with that these days?  I used to be able to so.

[Kenneth]

Zip the files and drag and drop them to this text box should work I believe. Please us 1Mohm pull down, and make sure the debugger is disconnected during testing. After programming the firmware (and once you get nrfjprog running) you can call "nrfjprog --debugreset" to make sure the chip is no longer in debug mode for remaining of test.

Kenneth

[Robin]

Hello Kenneth,

I believe I know the basics of what os going on now, and there maybe only one way to remedy this.  Please reference my latest case 274556, where I will describe what I have found, and why I believe ot to he the only practical solution to our problem.

Robin @ TL 

Hello Kenneth,

Please close this case and  reference the above stated case 274556 for any further communication.

Thank you

Robin @ TL