DocID024597 Rev 3 1215/1693
RM0351 Universal synchronous asynchronous receiver transmitter (USART)
1282
Figure 402. Transmission using DMA
Reception using DMA
DMA mode can be enabled for reception by setting the DMAR bit in USARTx_CR3 register.
Data is loaded from the USARTx_RDR register to a SRAM area configured using the DMA
peripheral (refer to Section 10: Direct memory access controller (DMA) on page 295)
whenever a data byte is received. To map a DMA channel for USART reception, use the
following procedure:
1. Write the USARTx_RDR register address in the DMA control register to configure it as
the source of the transfer. The data is moved from this address to the memory after
each RXNE event.
2. Write the memory address in the DMA control register to configure it as the destination
of the transfer. The data is loaded from USARTx_RDR to this memory area after each
RXNE event.
3. Configure the total number of bytes to be transferred to the DMA control register.
4. Configure the channel priority in the DMA control register
5. Configure interrupt generation after half/ full transfer as required by the application.
6. Activate the channel in the DMA control register.
When the number of data transfers programmed in the DMA Controller is reached, the DMA
controller generates an interrupt on the DMA channel interrupt vector.
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