Audio Playback and Record, DMA from RAM

[solomonviveros]

Posted on April 23, 2013 at 01:28

When executing the audio clip from flash[const defined location as in the example project] the audio file plays fine, but if I remove the ''const'' as to allocate ram for the audio clip, I get only a small block of white noise...I'd figure that given the DMA configured as memory-to-peripheral there to be no issue...looking at the output with a logic analyzer, the bytes appear to be the same in both conditions[audio clip executed from flash, and when from ram]...any suggestions as to what could be the subtle difference causing the problem would be much appreciated...

[solomonviveros]

Posted on April 23, 2013 at 01:30

...this is when using the Stm32F4Discovery board and keil included example code...

[dthedens23]

Posted on April 23, 2013 at 19:07

most likely a timing issue

reading const data (from flash) incurs some latency (section 3.4.1)

[solomonviveros]

Posted on May 02, 2013 at 17:35

It was a timing issue with how I was sending the data -- I'd send single blocks of data for which the code was powering down the codec after each block, then re-initializing when processing again which needed to be corrected :)