UART API types and use

[mexco]

I had a look on APIs to use UART in Zephyr in the link https://docs.zephyrproject.org/latest/reference/peripherals/uart.html#uart-interrupt-api. There are three types: Poll, Interrupt and Asynchronous using DMA. 1. In what situation which mode is prefrerd. 2. May, some one give an example of each? 3. Is it mondatory to use Semphore in Asynchronous mode ? 

[Amanda Hsieh]

Hi, 

1. In what situation which mode is prefrerd.

It depends on what benefit you want. See the explanation in this post. 

2. May, some one give an example of each?

 Poll (default): Low Power UART 

Interrupt-based UART: NUS on NCS: The Nordic UART Service with the nRF Connect SDK and HCI low power UART

Asynchronous using DMA: Bluetooth: Peripheral UART

3. Is it mondatory to use Semphore in Asynchronous mode ? 

No, Semaphore is not used in Bluetooth: Peripheral UART sample.  

Regards,
Amanda