RE: [Thingy91] BLE central using HCI crashing nRF52

Emil Blenow — Tue, 25 Mar 2025 13:13:04 GMT

Hi Kenneth,

I have looked into this a but more and it seems like the UART was misleading. I still get Rx disable failed when using LPUART but it should use the hfxo so not sure what that is about and since interrupt based UART works better we are stil using it.

We found that there was some writes across buffer boundaries that likely caused some of our issues.

We later had issues where RSSI read command timed out which seems to be resolved by disabling ACL flow control.

Best regards,
Emil

RE: [Thingy91] BLE central using HCI crashing nRF52

Kenneth — Wed, 12 Mar 2025 13:15:04 GMT

Hello,

The things I would have looked into:

- The most common problem with UART is a mismatch in UART baudrate, to ensure stable baudrate you need to explicit start the high frequency clock (hfxo) before sending and receiving UART data (this must be done on both sides).

- Another problem with UART, is that sometimes there will occur errors on UART (for instance framing error), in such case the UART typically will stop receiving the data, so the application will typically need to handle the UART error by starting the receive of UART again in this case. If you fix the baudrate (as suggested above) I expect the number of errors on the UART to drop significantly, but it's still a good idea to resume/start UART rx again on UART errors.

- Another idea to consider is to start scanning or connection with a timeout, e.g. that you start scanning with 60seconds timeout, then you will get a timeout after 60seconds (which indirectly will show that the device is working), and you can re-start scanning again if you want to.

Hope that helps,
Kenneth