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Modifying Rockbox to control an external digital potentiometer via iPod 5.5g

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dreamlayers:
The WM8758 DAC has a volume control which affects line out.  I've never seen a WM8758 datasheet, but the WM8983 datasheet describes this.  Search for DACLVOL and DACRVOL.  It's an 8 bit value allowing values between 0dB and -127dB in 0.5dB steps.  It is used by FS#10082, which has been committed.  The full range isn't used, but the code should be easy to change if you need more range.

axismundi:
Thanks everyone.

Indeed, the datasheet for WM8758 is not available, but apparently both WM8978 and WM8983 are almost equivalents, so I have been using the documentation available for these.

The chips have three stereo outputs, two of them being volume controlled (LOUT1/ROUT1, LOUT2/ROUT2) and one at fixed gain (OUT3/OUT4). I had assumed that the one used for line out is OUT3/OUT4 because this is what the datasheet implies (or sort of).

Finding out that I was wrong is very good news for me, I have high hopes on this. I'll work on it during the weekend, still need to do some reading and research to learn how to do it but I should be fine.

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