Hi, Nordic and all great guys,
I have a weird and terrible problem about our products,which used a MCU based on nrf51822. Some info about our product:this is a module powered by 12-24V DC power, BLE accepts commands from users and control a relay ,which will control the door lock, and a GPIO interrupt is set for a button at the inner side of the door,also control the relay,pretty simple.
The problem is that: we powered on several products for a long time ,at the beginning ,all are alive and work good, then after several days, some of them are "dead",no BLE advertising action, no GPIO interrupt response(the priority is low). However, the power supply is always working,the VDD voltage is still 3.2V to 3.3V even the product is dead. When we disconnect the power line and reconnect it , the product works again ,but we are worried that sometime in the future it will "die" again. We need these products work without any "undetectable time", until it break down totally. It seems that the MCU is going to certain kind of unknown state, the code is no longer running even the power is normal,but we have not found the cause.our code is an interrupt based program, all activity are done in the interrupt response, we have BLE,GPIO,APP_TIMER,our other products using the same program pattern have not met this problem. The attachment is our schematic diagram,maybe someone can find the problem or strange things from hardware aspect,any help and advice are appreciated, if more information needed, please add a comment below and I will reply.THANKS ALL.schematic diagram.pdf
updated 8-11: The power up voltage waveform is like this:scope_12.png
when buzzer is on, the VDD waveform is like this :scope_14.png
updated 8-22: the full PCB layout is here:Lock_control13.PcbDoc
