Application examples

AN3126

20/24

Doc ID16895 Rev 2

Figure 16. Wave Player flowchart

(*) when DMA is transferring data from one RAM buffer, CPU is transferring data from the

MicroSD Flash memory to the other RAM buffer.

ai18315

Enable DMA,TIM6,DAC clocks

WavePlayer_menuStart()

Config DAC channel 1 to be triggered

by TIM6 TRGO

Config DMA ch3 to transfer 512 bytes

from wavBuffer1 to DAC ch1 8bit

DHR register

Enable DAC channel 1 and DMA

connection

Enable DAC channel 1 output

Parse the .wav file to Check if it is a

Valid file and Get all needed

information from the .wav header.

Display Error

if .wav file status OK

Connect TIM6 TRGO to its update

event

Enable TIM6

(start the Transfer from RAM to DAC)

Enable DMA channel3

Configure the TIM6 frequency to have

the correct .wav sample rate

Initialize WaveDataLength with .wav

file audible data size

if WaveDataLength!= 0

Read 512 next bytes from the .wav file

and Save them in wavBuffer2

(*)

If DMA transfer from wavBuffer1 to

DAC ch1 is completed

(*)

Clear DMA channel3 flag

Decrement the WaveDataLength by 512

and if WaveDataLength < 512 then

WaveDataLength = 0

Disable DMA , Config DMA to transfer 512

bytes from wavBuffer2 to DAC ch1 8bit

DHR register, and enable DMA

Read 512 next bytes from the .wav file

and Save them in wavBuffer1

(*)

If DMA transfer from wavBuffer2 to

DAC ch1 is completed

(*)

Decrement the WaveDataLength by 512

and if WaveDataLength < 512 then

WaveDataLength = 0

Clear DMA channel3 flag

Disable DMA, Configure DMA transfer 512

bytes from wavBuffer1 to DAC ch1 8bit

DHR register, and Enable DMA

Disable DMA

Exit

Yes

Yes

Yes

No

No

No