RE: Clarification of UART instances on NRF52840

Susheel Nuguru — Tue, 22 Nov 2022 13:03:37 GMT

APP_UART uses hardcoded instance in app_uart.c and app_uart_fifo.c in the below line.

static nrf_drv_uart_t app_uart_inst = NRF_DRV_UART_INSTANCE(APP_UART_DRIVER_INSTANCE);

It is a bit tricky to do multiple instances but it is possible. You need to have two instances of app_uart and edit the names like the API. For example you can have two new files into the project like devzone.nordicsemi.com/.../app_5F00_uart1.h

devzone.nordicsemi.com/.../app_5F00_uart1.c

Where I have changed the API in app_uart1.c to have app_uart1_init etc.

I also have app_uart_inst in app_uart1.c to use APP_UART_DRIVER_INSTANCE_1 (instead of APP_UART_DRIVER_INSTANCE) which you should add in your sdk_config.h file to use the second instance of the uart in app_uart1.c.

And yes if you want app_uart to be used for two instances it is NOT possible without editing the libraries files.

Second way is to use app_uart for one instance and nrf_drv_uart directly for the second instance.