Low level UART and Timer drivers

[firmware_master]

Hi,

I have been looking at the Nordic examples and I found them to be pretty slow with the handlers being the bottleneck as opposed to the actual hardware. I was wondering what is the lowest level drivers that I can use for my applications that involve UART and timers. I also wanted your opinion on the quality of these drivers.

Thanks

[Kenneth]

Moving forward I would suggest using the nrfx drivers, these will be maintained for a long time to come:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/nrfx_migration_user_guide.html?cp=5_1_2_5 

[firmware_master]

I checked the BLE_UART example and it seems like it is using the nrfx drivers but I'm not sure. In the central device, for example, I checked app_uart_put()->nrf_drv_uart_tx() which calls nrfx drivers with functions like nrfx_uarte_tx() and nrfx_uart_tx().  I am receiving all correct BLE data on a central device, but there are bytes being lost when adding the data to the UART.

I checked by doing the following:

I counted the number of times app_fifo_put() was called and the number of times nrf_drv_uart_tx() was called. The sum of these is not equal to the number of bytes received by the BLE application in total.

Let me know what you think of this.

Thanks

[Kenneth]

Hi,

By any chance app_fifo_put() return NRF_ERROR_NO_MEM?
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/lib_fifo.html?cp=5_5_0_3_14 

Tried increasing the UART baudrate?

Best regards,
Kenneth

[Kenneth]

Alternatively I would recommend to try nrf_libuarte_async driver for UARTE and lossless reception without HWFC. There are experimental_cli_libuarte and experimental_libuarte example in the SDK that show usage. They are labelled experimental due to lack of documentation but it has been thoroughly tested. The stability and quality of the libuarte is very good. The libuarte library requires one TIMER, one RTC or TIMER, couple of PPI channels (~3 if recall correctly). It is using TIMER via PPI to count exact number of bytes received without stopping uarte.

Best regards,
Kenneth