generic UART example for STM32 using CubeMX HAL

loccd wrote on Monday, December 25, 2017:

Hello: I am self-teaching myself STM32 and FreeRTOS, and I am having difficulty finding examples for this stuff compared to the plethora of examples I was able to gather when learning AVR’s and arduino-land. I am trying to make a base for myself to use whenever I start a new project, and I am getting stumped on how to effectively use a UART with the CubeMX HAL and FreeRTOS.

In 2009, someone asked this very question, and the founder of FreeRTOS made a suggestion:
“…an efficient way would be to have a DMA pass data to and from the UART and a circular buffer. Then have the DMA interrupt use a semaphore to unblock tasks when there is enough data to make it worth processing.”

So my question: does someone have an example of this working, ideally with the CubeMX HAL? I have been reading about task notifications (which I can use, since CubeMX uses FreeRTOS v9.0), is there an example that does this with those instead of semaphores? My base code that I am trying to port from arduino land, uses a command parser that can accept messages of varying length, and I need to keep that functionality.

I apolgize in advance for the n00b question… it is hard for me to take everything I’ve learned thus far and start from a blank page, and example to learn from would help me greatly. Thank you in advance :slight_smile:

rtel wrote on Tuesday, December 26, 2017:

Specifics of FIFOs and DMAs are chip specific as the hardware moves the data, so outside of the scope of FreeRTOS support. The following file provides a heavily commented example of how to use a stream buffer to send data from an ISR to a task using software

You can look at the source code on the direct to task notification documentation pages to see how to signal a task from an interrupt using a notification. If you were using a DMA to move data then the ISR would be the DMA end interrupt:

loccd wrote on Wednesday, December 27, 2017:

THANK YOU… that example is more or less exactly what I was looking for.