nRF51822s mysteriously died after hours of operation

[jtrovato]

I am working on a project where my nrf51822 is on for long periods of time in lower power mode. Yesterday I made some updates to the code and the devices were working fine with the new updates, then when I came in this morning after they had been on for a night none of the nrf51s (There were 5 devices) would boot. The RTT Viewer showed nothing. And hard resets and toggling power did nothing. Not even reflashing the application could get them out of whatever state they were in. I was only able to fix the issue after using nrf go studio to erase all of the devices, flash new bootloaders, softdevices, and applications.

No core reset or power functions or the bootloader were updated.

I am really confused about what happened and a little bit scared to reintroduce new updates. Any ideas or help would be appreciated.

[jtrovato]

Code changes include adjusting one of my Application Timers and its timeout handler. Instead of limiting BLE communications to 4 packets per interval, I now wait for the BLE_ERROR_NO_TX_PACKETS error to increase throughput. And I changed a few print statements. I have not been able to reproduce the issue in the last 8 hours of the device being on but when I do, I will use the debugger to get some more information.