USART idle interrupt transfer by DMA

Demonstrate the use of USART data receiving and sending by idle interrupt and DMA transfer. This method can receive variable-length data through USART DMA, but the data received at one time cannot exceed the maximum receiving length set by DMA transfer.

Connect the PA9 and PA10 of the experimental board to the USB-to-serial port tool, and then connect the tool to the USB of the host computer, open the serial port assistant of the PC host computer, and the MCU will print information after power-on and reset, and then if it receives a message from the PC For the data, the MCU will return the same data, and verify the correctness of data transmission and reception through the serial port assistant.