UART / Serial APIs for single character tx/rx

RE: UART / Serial APIs for single character tx/rx

Aadishri GS — Wed, 22 May 2019 12:16:19 GMT

[quote userid="77782" url="~/f/nordic-q-a/47554/uart-serial-apis-for-single-character-tx-rx/188547"]nrfx_uart_rx must be called to setup a receive operation[/quote]

Once I call this function, the Rx will happen continuously over the backend(like a separate thread running continuously in an infinite loop) when interrupt arrives each time. It is non-blocking as I am providing event_handler in init.

Am I right?

RE: UART / Serial APIs for single character tx/rx

Amanda Hsieh — Wed, 22 May 2019 12:02:56 GMT

Hi,

nrfx_uart_rx must be called to setup a receive operation.

Otherwise, it looks ok.

-Amanda

RE: UART / Serial APIs for single character tx/rx

Aadishri GS — Wed, 22 May 2019 08:44:11 GMT

I am looking for IRQ based implementation without easy DMA.

This QA suggests I use nrf_serial which used nrfx_uart instead of app_uart in UART example.

Any suggestion on sequence of APIs nrfx_uart APIS that I must use in sequence? Does the below sequence do?

1. nrfx_uart_init() -> with nrfx_uart_event_handler_t event_handler for IRQ handling during Rx

2. nrfx_uart_tx() -> whenever I want to transfer a byte

3. Event handler will be called automatically on IRQ for RX

Should I take care of anything more?

RE: UART / Serial APIs for single character tx/rx

Amanda Hsieh — Tue, 21 May 2019 11:33:36 GMT

Hi,

There is only a legacy API layer that connects legacy API to NRFX API. Please see this page for more details.

The ble_app_uart example uses the new nRFX UARTE drivers and the UARTE hardware abstraction layer (UARTE HAL).

This is maybe more clear in the migration document for SDK 15.0.0. The drivers should be very similar expect the names, but have been splitted into two separate drivers for EasyDMA and non-EasyDMA.

-Amanda

RE: UART / Serial APIs for single character tx/rx

Aadishri GS — Tue, 21 May 2019 08:08:08 GMT

I donot see any example using new APIs. Is it possible to share one?

Also, I understand the main difference between old/new lib/app/driver is EasyDMA implementation in new. Please correct me if I am wrong

RE: UART / Serial APIs for single character tx/rx

Amanda Hsieh — Tue, 21 May 2019 06:48:47 GMT

Hi,

There are various UART drivers and libraries in the nRF SDK, e.g. app_uart ("old" lib), libuarte ("new" lib), nrf_drv_uart ("old" driver) and nrfx_uarte ("new" driver).

They provide different abstraction and functionality of using the UART peripheral in an application.

In general the nrfx* is the low level driver that give you full control over the peripheral, while the app*/lib* library give you more high level api where you don't need to think about the low level hardware registers.

Which to use depends on your requirements, if you find that the app*/lib* provide the functionality you need then there is no need to use the nrfx* driver.

I will suggest you take a look at the following examples and start from them

nRF5 SDK v15.3.0: UART Example

nRF5 SDK v15.3.0: UART/Serial Port Emulation over BLE

Best regards,

Amanda