BC127 - 12S Volume Control

Hello,

I’m using a BC127 in 12S mode with a TI PCM5102A DAC and volume control isn’t working. The audio coming from the DAC is extremely distorted. When I change the volume on the BT device (a phone), there is no change in audio volume, even when muted.

This is my current config on Melody 7.2:
SET GPIO_CONFIG=OFF 0
SET AUDIO=0 1
SET AUDIO_ANALOG=15 15 1 ON
SET AUDIO_DIGITAL=0 44100 64 100C00 OFF
BT_VOL_CONFIG=A 60 10 1

According to the Melody guide, the last parameter of BT_VOL_CONFIG is set to DSP, therefore I should see a change in volume, right?

Thanks!
-Ted

As a follow up, I am able to get the output to mute when VOLUME is 01 or 02 on the A2DP Stream. I also tried setting BT_VOL_CONFIG=A 60 10 0 (Volume control at the built in DAC) as a test and that made no difference.

@mlw,

My apologies for tagging you directly, but would it be possible for you to have a look at this and tell me what I’m doing wrong? :slight_smile:

Thanks!
-Ted

Another follow up:

I added a pair of 10k resistors to the output so I could troubleshoot with a pair of earbuds without destroy my hearing – this toned down the output but I can now tell that the gain is way too high. Issuing VOLUME 10 2 makes no difference, either.

Additionally, I downgraded to Melody 6.1.5, which made zero difference.

I figured it out after smashing my head against it for a longer period of time.

The problem is that the PCM5102A expects the MSB to occur after the first clock cycle, not the second as is the default configuration.

This parameter fixed it:

SET AUDIO_DIGITAL=0 44100 64 100800 OFF