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What is DMA Usart?
DMA mode: DMA is used to transfer data from USART RX data register to user memory on hardware level. No application interaction is needed at this point except processing received data by application once necessary. PROS. Transfer from USART peripheral to memory is done on hardware level without CPU interaction.
How is DMA implemented?
2) The DMA controller starts the operation on the device and requests the bus. Once the bus is granted to DMA, it then waits on the Source Device to provide data. When the data is available, it transfers the data to the destination. The DMA controller supplies the memory address for reads and writes.
When to use DMA mode for UART data?
Interrupt service routine gets executed for every received character May stall other tasks in high-performance MCUs with many interrupts May stall operating system when receiving burst of data at a time DMA mode: DMA is used to transfer data from USART RX data register to user memory on hardware level.
How is UART data reception handled in ISR?
The CPU initializes the UART receive hardware so that it fires an interrupt signal whenever a new byte of data is received. And in the ISR code, we save the received data in a buffer for further processing. This way of handling the UART data reception is a non-blocking way.
Which is the best way to receive UART?
And lastly, and most importantly, the DMA UART receive method which doesn’t require any CPU intervention at all and can be considered the most efficient way to achieve this task. All the example code/LABs/projects in the course are going to be done using those boards below. Some Extremely Useful Test Equipment For Troubleshooting:
How to receive UART serial data with STM32?
This way of handling the UART data reception is a non-blocking way. As the CPU initiates the receiving process and it resumes executing the main code. Until an interrupt is received, then it freezes the main context and switches to the ISR handler to save the received byte to a buffer and switches back to the main context and resume the main code.