AN4104

DMA programming examples

Doc ID 023131 Rev 1

11/13

configured to be triggered by TIM2 TRGO triggers and without noise/triangle wave

generation. 12bit right data alignment is selected since we choose to access DAC_DHR12R

register.

3.4

SPI DMA example: communication between two SPIs using

DMA

This example provides an SPI communications using DMA.

In master board, the SPI peripheral is configured as Master full duplex with DMA and NSS

hardware mode.

The TIM2 is configured to generate 4 KHz PWM signal with 50% duty cycle on TIM2_CH2

pin (PA.01), this signal is used as DMA trigger and as NSS signal input to latch the SPI data

transfers. Whereas in Slave board, the SPI peripheral is configured as Slave Full duplex with

DMA and NSS hardware mode.

●

The Master sends the specific command to the Slave using the TIM2_CH2 DMA

request (DMA1_Channel3) (the command contains the transaction code

(CMD_RIGHT, CMD_LEFT, CMD_UP, CMD_DOWN or CMD_SEL) and receives the

ACK command from the Slave using SPI_Rx DMA request (DMA1_Channel2).

●

The Slave receives the command using SPI_Rx DMA request (DMA1_Channel2) and

sends the ACK command using the SPI_Tx DMA request (DMA1_Channel3).

3.5

USART communication boards data exchange using DMA

example

This example provides a small application of USART communications using DMA.

In both boards, the data transfers is managed using the USART Tx/Rx channels DMA

requests.