STM CircleOS forum / Distortion on audio output

repzak · 2009-03-02 19:01:09

Hello,

Anyone tried to run audio out at 44.1Khz?

I have en small example running, but there are some distortion, i can't figure out if it is hardware or software related...

Anyone have perfect sound out?

Kasper

repzak · 2009-03-02 19:29:39

Btw.. Could be issues with IRQ functions...

I think i have seen SPI3 has the highest priority, am i correct on that?

Kasper

Francis · 2009-03-02 20:09:11

The highest priority is for Timer2, that calls the management of the SPI (for the MEMS) and the I2C. The problem with I2C+audio is that it freezes when it is interrupted... Thus, we had to keep the highest priority for this.

repzak · 2009-03-02 21:09:49

Hello,

This is what i get from the Source:

SPI3
PreemptionPriority = 0
SubPriority = 0

TIM2
PreemptionPriority = 1
SubPriority = 1

Systick
PreemptionPriority = 3
SubPriority = 3

So, for me it seems the highst irq are SPI3 and it can interupt the other interupts...??

or do i understand it uncorrectly?

Kasper

Francis · 2009-03-03 21:38:47

It seems that you are right... sorry.

# 1 2009-03-02 19:01:09 Distortion on audio output

Distortion on audio output

# 2 2009-03-02 19:29:39 Distortion on audio output

Re: Distortion on audio output

# 3 2009-03-02 20:09:11 Distortion on audio output

Re: Distortion on audio output

# 4 2009-03-02 21:09:49 Distortion on audio output

Re: Distortion on audio output

# 5 2009-03-03 21:38:47 Distortion on audio output

Re: Distortion on audio output

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