Posted on November 03, 2016 at 17:14It is important to specify the specific part in question, it is hard, and unnecessary to have to wade through older threads to determine context.
On several STM32 parts not all UART support DMA, DMA Channels/Streams are also a limited resource, with limited flexibility. ie easy to get conflicts, and run out of options. Review the Reference Manuals to determine what does what.
The UART is a subset of the USART functionality, very few people use the Synchronous mode, and it is far from a optimum implementation. The UART also tend to be on the slower APB bus, but likely not an issue for sub-Mbps implementations.
DMA for USART/UART works most effectively for larger buffer TX operations, ideally where you can transmit data in place rather than copying into other buffers.
