Am Freitag, 15. Oktober 2010, 11:03:21 schrieb Daniel Mack:
On Fri, Oct 15, 2010 at 10:59:32AM +0200, Julian Scheel wrote:
Am Donnerstag, 14. Oktober 2010, 17:39:13 schrieb Daniel Mack:
Well, even if it was, you should hear some sound. It might be distorted, but if you don't get any output, the reason is somewhere else.
Did you check the schematics of your board in comparison to the reference diagrams in the codec's datasheet? Are there any other things to be considered maybe?
What about the voltage levels? Are they within the specs? I had a quick look and it seems that Vdd on the codec has to be within 3.0 .. 3.6V, while the signals you provide rather seem to be in the range of 5V? The absolute maximum ratings say that Vdd must not be greater than 4.0V.
Sorry for one more off-topic mail, but I rechecked it. Digital Input Voltage is -0.3V to 6.5V, so my 5V clock voltage should be fine imho. Vdd is 3.0V on my board... Do you maybe have any other thoughts what might be wrong here?
No, sorry. I think you're doing the right thing by analyzing the digital stream carefully and checking the electrical components around the codec. There's usually a ton of things to consider, but it's hard to tell what to look for without having the same hardware.
Still, let me know what you find :)
Just figured out what went wrong. The PCM1794A requires the I2S signal to contain 24 bit. So when running in 16 bit mode one has to fill up with 8 zero bits. Now I doubled the BCLK so that I would be able to send 32 bit to the DAC. Still am fighting a bit with the AT91's SSC controller to send only one package per L/R frame, but in general I am seeing a proper signal behind the DAC now!
Regards, Julian