DMA programming examples

AN3117

18/28

Doc ID 16846 Rev 4

4

DMA programming examples

All the examples described below use the STM8L05x/STM8L15x/STM8L16x/STM8AL31x/

STM8AL3Lx standard peripheral library and are provided in the firmware package

associated with this application note.

4.1

Memory to peripheral transfer example: transferring



waveform data from Flash memory to DAC

This example uses the DAC peripheral to generate a signal (stored in a Flash memory

buffer) using DMA memory to peripheral mode.

Figure 3.

Transferring data from Flash memory to DAC

The DMA event is provided by the external hardware DAC trigger (TIM4_TRGO). Each time

the external DAC trigger occurs, the DMA transfers data from the Flash memory buffer to the

DAC data holding registers.

Since the DMA is configured in circular mode, the DAC is triggered periodically by TIM4.

The DMA transfer from the Flash memory buffer to the DAC is repeated indefinitely.

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

STM8AL3Lx standard peripheral library package.

DAC

DMA1

Channel 3

Data 01 L

Data 02 H

DAC_RDHRH

DAC_RDHRL

Data n H

Data 02 L

Data n L

DMA

source

DMA

destination

DAC_OUT

DAC_trigger

System

bus

Program bus

ai17418

Data 01 H

DMA1 bus