Disable AUDIO_L output signal

[Cyrilou]

Hi,

I'd like to disable this output by software because screen emits 20db peak on spectrum analyser on near field with ffc20 ribbon. This is problematic for CE certification.

When I cut AUDIO_L line on FFC20 ribbon on screen side, it's ok! But I need a software solution.

What should I try?

If I disable audio engine (reg_cpureset=4), output is still active.

What in theory could OFF AUDIO_L pin, I see nothing in BT815 datasheet, there is always 30Mhz sinusoidal signal in idle (no sounds played).

Thank you.

[BRT Community]

Hello,

One way is to play the 'silence' sound by writing 0x00 to the REG_SOUND register.

You can find details of the audio playback registers in section 4.7 of the datasheet,
https://brtchip.com/wp-content/uploads/sites/3/2022/04/DS_BT81X-1.1.pdf

Best Regards, BRT Community

[Cyrilou]

Hi,

This doesn't work. I tried another one.
I wrote 0x04 at hidden address 0x3020E4, this reduces signal to 140KHz and that's all.

[BRT Community]

Hi,

Could you advise which EVE device you have?

Best Regards, BRT Community

[Cyrilou]

Hi it's a Matrix Orbital 43A IPS with EVE3 BT815 chip.

[pauljiao]

can try to play "mute" to get the AUDIO_L pin low:

write 0x60 (mute) to REG_SOUND.

It should make AUDIO_L pin low...