DMA programming examples

AN3117

20/28

Doc ID 16846 Rev 4

4.3

Peripheral to memory transfer example 2: transferring data



from the USART to the RAM

This example uses the DMA peripheral in circular mode to transfer data from the USARTx

peripheral to the RAM memory. When a character is received by USARTx, it is transferred to

a specific RAM buffer using the DMA.

Figure 5.

Transferring data from the USART to the RAM

The DMA event is provided by the USART_RX.

The code for this example is provided in the STM8L05x/STM8L15x/STM8L16x/STM8AL31x/

STM8AL3Lx standard peripheral library package.

Note:

USART DMA Channel RX can be DMA channel 2 or DMA channel 3 respectively for

USART1 and USART2.

USARTx

USART DMA1

hannel

CRX

USARTx_DR

DMA

destination

System

bus

RAM bus

DMA

source

ai17420c

Data 01

DMA1 bus

Data 02

Data 03

Data 04