Zhenhua Huang

BT lost in a week, could not recover without a hardware reset

Discussion created by Zhenhua Huang on Jun 19, 2017

Hi, ST experts:


We meet a stability issue with BlueNRG-1.


HW: BlueNRG-1 minimal system, 16MHz external Crystal, NO DCDC.

SW: Based on DK2.1, Disable low power features. Firmware will log some data into Flash but not very frequently. Such as every 5~10 minutes, 5 bytes will login.


We have a sets of BlueNRG(6). An app connect with them to retrieve data from Flash every 5~10 minutes. In one week, one or more BlueNRG-1 lost BT permanently. They could be found again except do a hardware reset.


Experiments we have done and verified:


1. BT stack will be affected by Flash erasing or contentiously multiple writing operation. Eg: Flash erasing needs 21.5mS. During erasing period, CPU could not run instructions. BT ISR and tick handle is paused. After several contentious erasing, BT stack is crashed down. Only power cycle could resolve this issue.


2. If disable interrupt for a longer time, BT stack will down. Same reason as 1.


3. I confirmed from reset reason. Neither WD reset nor system reset could not reset BT. A hardware reset is the only way. BT part is out side the control of reset circuit.


From our logs, we had no Flash erasing nor long time interrupt disabled. We do have Flash writing for several bytes(4~20 Bytes). During the writing, we did not disable the interrupt. CPU might be paused for about 430uS maximally. And the Bluetooth ISR is guaranteed.


Please kindly help to confirm:

If these is available solution to reset the BT stack. Our products needs to run on a device for year without power down. For instance, if it is possible to shutdown the internal LDO to power cycle BT?


Best Regards.