Contents

AN3117

2/28

Doc ID 16846 Rev 4

Contents

1

DMA controller description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.1

DMA main features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.2

Peripherals supported by DMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2

Performance considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.1

DMA latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.2

Data bus bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3

Programming the DMA using the standard peripheral library . . . . . . 12

3.1

Configuring the DMA peripheral to transfer data . . . . . . . . . . . . . . . . . . . 12

3.1.1

Configuring the DMA channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.1.2

Selecting the channel request source . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1.3

Enabling the DMA transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.1.4

Configuring the arbitration delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2

Supervising the DMA transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2.1

Method 1: Current data counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2.2

Method 2: Flags/interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4

DMA programming examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.1

Memory to peripheral transfer example: transferring



waveform data from Flash memory to DAC . . . . . . . . . . . . . . . . . . . . . . . 18

4.2

Peripheral to memory transfer example 1: transferring data



from the ADC to the RAM via multi channel acquisitions . . . . . . . . . . . . . 19

4.3

Peripheral to memory transfer example 2: transferring data



from the USART to the RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

4.4

DMA transfer examples in low power mode . . . . . . . . . . . . . . . . . . . . . . . 21

4.4.1

DMA transfer example in Wait for event (WFE) mode . . . . . . . . . . . . . . 21

4.4.2

DMA transfer example in Wait for interrupt (WFI) mode . . . . . . . . . . . . 22

4.5

DMA transfer example with TIM1 in Burst mode . . . . . . . . . . . . . . . . . . . 22

4.6

DMA channel priority transfer example . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.6.1

Transfer example case 1: hardware priority configuration of DMA



channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.6.2

Transfer example case 2: software priority configuration 1 of the DMA



channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24