AN3117

DMA programming examples

Doc ID 16846 Rev 4

25/28

Transfer results are shown in Table 13.

4.6.3

Transfer example case 3: software priority configuration 2 of the DMA



channels

In this example, the software priority of the channels is updated as shown in Table 14

Figure 10.

Example case 3: DMA channel data transfers as a function of time

Table 13.

Results of example case 2

Time

RAM Buffer1

TIM1 ARRL

TIM2 ARRL

TIM3 ARRL

TIM4 ARR

RAM Buffer2

t0

0x00

0x11

0x22

0x33

0x44

0x55

t1

0x11

-

-

-

-

-

t2

-

-

0x11

-

-

-

t3

-

-

-

-

-

0x44

t4

-

-

-

0x44

-

-

Result

0x11

0x11

0x11

0x44

0x44

0x44

Table 14.

Example case 3:

priority configuration of the DMA channels

DMA channel

HW priority

SW priority

Channel 0

Very high

Medium

Channel 1

High

Very high

Channel 2

Medium

High

Channel 3

Low

Low

time

t0

t1

t2

t3

t4

ai17425

Hardware priority

Channel 0

Channel 1

Channel 2

Channel 3

Transfer B

Transfer C

Transfer A

Transfer D