UART receive in background without callback on nRF52 SDK11

[puz_md]

Hi, I'm looking for an easy way to use the UART in blocking mode (or something similiar) with a receive buffer that is filled in background:

• If possible using EasyDMA for better performance and easier software design
• TX data may either block until all data has been sent or may return immediately and provide an additional function call to check if all data has been sent successfully.
• RX data shall received in background and stored in a buffer/FIFO. It shall be possible to read data of arbitrary size from the receive buffer without stopping reception.
• No callbacks or event handlers shall be used (synchroneous control flow in application).

In the past, on the nRF51, we used the app_uart library with FIFO support. Looking at the SDK11 documentation on infocenter.nordicsemi.com, I couldn't find any information about this library (although the directory is still there in the SDK11 archive). Is app_fifo still working on SDK11 on nRF52? Does it take advantage of the EasyDMA feature?

Looking at nrf_drv_uart.h, double buffering is mentioned to provide support for continuous data reception in non-bocking mode. But what does happen if the last received data byte does not fill the buffer to 100%? Will the driver wait for more bytes until the buffer is full, not giving any opportunity to receive data from the partially filled buffer? In other words, is there any possibility to receive "byte streams" of arbitrary length using UART with EasyDMA (something like app_uart with FIFO feature using EasyDMA)?

[puz_md]

@bat13: if you want to receive continuous data, you can use nrf_drv_uart in EasyDMA mode. As far as I understand, you will get callbacks each time a complete buffer has been received (I didn't try it out yet, though).

If you want to receive continuous data, the current driver should just work fine (use the double buffering by handing over two buffers with nrf_drv_uart_rx(), and one buffer each time you get the data ready event). But if the data stream suddely stops and your buffer does not become full with the last rx byte, you might wait forever for the final data bytes.