Bluetooth (SoftDevice) + high speed UART (libuarte)

[VGKilian]

Hi,

Currently I’m working on a device which is, on the one side connected to a smartphone via BLE and on the other side to another uC via UART.

Therefore, the UART speed is fixed to 1MB/s. For this reason, I must use DMA to get the UART running.

We use the nRF52840 DK.

I had a look to the example projects “ble_app_uart” and “libuarte”. Both projects fulfil our requirements to the BLE and UART connection.

Now I try to merge these projects and I’m struggling with the RTC’s.

I read that the Softdevice uses RTC0 and Timer0. Meanwhile the app_timer library is used the RTC1.

Is it true that there is no free RTC for the libuarte library?

So, I have no chance to get it running with the nRF52840?

 

Thank You,

Kilian

[Dmitry]

Hi,

libuarte can use either RTC or TIMER instance:

_rtc1_idx	RTC instance used for timeout. If set to NRF_LIBUARTE_PERIPHERAL_NOT_USED then TIMER instance is used or app_timer instance if _timer1_idx is also set to NRF_LIBUARTE_PERIPHERAL_NOT_USED.
_timer1_idx	TIMER instance used for timeout. If set to NRF_LIBUARTE_PERIPHERAL_NOT_USED then RTC instance is used or app_timer instance if _rtc1_idx is also set to NRF_LIBUARTE_PERIPHERAL_NOT_USED.

[Simonr]

Hi Kilian and Dmitry

The nRF52840 has 3 RTCs so you should be able to use RTC2 as well if you don't want to follow Dmitry's advice.

Best regards,

Simon

[VGKilian]

Hi Dmitry and Simonr,

thanks a lot for your help.

I tried both of our suggested solutions and it takes me a step further.

But now the "app_error_fault_handler" function gets called. The address of the pc is located in nrfx_timer.c.

Could you tell me which timers are used in “ble_app_uart” and “libuarte” examples?

I use Timer1 and Timer2 for the libuarte.

Best Regards,

Kilian

[Simonr]

Hi Kilian

The ble_app_uart example uses Timer1 and runs the SoftDevice which uses RTC0 and Timer0, so you're probably having trouble because the ble_app_uart and libuarte are now both trying to use Timer1.

Best regards,

Simon

[VGKilian]

Hi Simon,

i have tried Timer2 & RTC2 (NRF_LIBUARTE_ASYNC_DEFINE(libuarte, 0, 2, 2, NRF_LIBUARTE_PERIPHERAL_NOT_USED, 255, 3)) and Timer2 & Timer3 (NRF_LIBUARTE_ASYNC_DEFINE(libuarte, 0, 2, NRF_LIBUARTE_PERIPHERAL_NOT_USED,3, 255, 3);).

Both with the same result. 

I start the program with BLE running, everything works fine. If the UART communication starts the error accrues.

The pc point at nrfx_timer or nrtx_rtc.

Best regards,

Kilian