nRF52840 BT Characteristic Notify only works when debugger is attached

RE: nRF52840 BT Characteristic Notify only works when debugger is attached

Amanda Hsieh — Wed, 20 Nov 2019 12:11:12 GMT

I would recommend that you have a look at the RTT description on Seggers webpage.

-Amanda H.

RE: nRF52840 BT Characteristic Notify only works when debugger is attached

BEplane — Tue, 19 Nov 2019 16:08:44 GMT

My assumption is that without the debugger attached the RTT log is not emptied, therefore setting it to block will not work ever when not connected to the debugger to empty the RTT log.

We also saw without the setting set to block we would end up dropping some logs (if we were printing a large amount of logs) This is not ideal, because the to prevent drops we block, but this breaks to code from working when not attached to a debugger. The fix would be to have multiple build and debug configurations, and that can be a hassle, then there are two builds to verify work properly.

Our eventual work around will be to use UART, and printf. This will print out regardless of being attached or not, and to get the prints all you do is connect with putty.

The advantages of RTT are unclear to me.

RE: nRF52840 BT Characteristic Notify only works when debugger is attached

Amanda Hsieh — Mon, 18 Nov 2019 07:18:33 GMT

Hi,

SEGGER_RTT_CONFIG_DEFAULT_MODE is configured for the RTT behavior if the buffer is full in sdk_config.h by setting it to the mode you want.

The following modes are supported:

SKIP - Do not block, output nothing.

TRIM - Do not block, output as much as fits

BLOCK - Wait until there is space in the buffer

The default mode is SKIP.

Could you also test with <nRF5_SDK>\examples\ble_peripheral\ble_app_uart? Do you see the same symptom? If not, could you compare the sdk_config.h to see the differences?

-Amanda H.