NRF51822 boards with bluetooth connection issues are fixed with soft reset but not pin reset

[youngwallaby]

Hello,

The current project I am troubleshooting includes an NRF51822 chip. The project includes a boot loader, application hex, and soft device S110 V7.3.0. It was noticed by the manufacturer that about 5% of the boards experience a dropping of the Bluetooth connection randomly. These boards that experience the connection dropping continue this behavior after being reprogrammed and power cycled. The only way we have found to fix it is to perform a "soft reset" using the nrfjprog command line tool. this soft reset will cause the board to stop dropping the Bluetooth connection until the next power cycle where it begins with the old behavior. Both the pin reset on the chip and the pin reset command on the command line tool were not able to replicate this fix as the soft reset did. 

I know there are function that would allow us to perform a soft reset from within the application, say on first power up write to EEPROM and then do a soft reset. second power up read EEPROM and then continue with normal functionality. I am looking for a more permanent solution for this problem. Any suggestions?

Thanks,

[youngwallaby]

Jared,

I wanted to share what I found to be the problem. It looks like the sleep mode for this unit was not configured properly. Of the two sleep modes, Constant latency and low power, neither were explicitly chosen. Once the sleep mode constant latency was chosen and the boards were reprogrammed the issue with the bluetooth connection dropping went away. 

Thank you for all of your help,