Portable speaker - Bypassing automatic zero-detect mute

[batou]

Hi I've recently acquired a 'Marley Get-togther', a fairly expensive and good-sounding speaker that has Bluetooth as well as analog inputs.

The mute-circuitry is way too aggressive though - you can't use it to watch a movie at all, or listen to any music with quiet or silent sections. And it has a lag as it comes out of mute.

I took a look inside and found an STA559BW '2.1 channel high-efficiency digital audio system Sound Terminal' (https://www.st.com/resource/en/datasheet/sta559bw.pdf). I believe its doing the muting internally, and this is configurable in a register. I traced back the I2C lines and they go to something that I am assuming is some kind of PIC with built-in flash. Part number SS(i?)95f116.

I checked the power supply, power-off and reset lines of the STA559BW and none of them are changing as this thing goes in and out of mute.

I think the proper way to disable the mute would be to download the firmware of the PIC (if possible?) reverse-engineer it, but I'm not set up for that and that seems fairly involved. What other options do I have? Would there any easy way to spoof an input signal, without causing audible noise or affecting sound quality?

Thanks y'all

[amyk]

The '95f116 is probably a MB95F1xx series MCU which seems to have originally been made by Fujitsu, then became Infineon and then Cypress. If it isn't continuously causing activity on the I2C, you may be able to code your own MCU to take control of the lines and flip the appropriate bits in the config registers to disable the automute after the main MCU is done, or even "proxy" the data and modify the config write appropriately.

[MathWizard]

Is there any external RC timing doing the mute time ? Maybe it's not done that way at all, but maybe.