Hi everyone,

I've developed an RS232/UART controller for the Sony STR-ZA****ES AVRs on an ESP8266 chip running ESPHome, and have integrated it into Google home so that I can control it with voice commands. %95 of the RS232 commands from the relevant sony CIS document (Cis0010, Version 1.08.0, dated 13-May-08) works fine. I have implemented all the main functions. Everything is working fine except the "set volume" command.

As per the document, it should be:
0x02 0x06 0xa0 0x52 0x00 0x01 0xa6 0x00 0x61 to set main room to -90dB
or
0x02 0x06 0xa0 0x52 0x00 0x02 0x00 0x01 0x05 to move main room vol +1step.
but these do not work.
only increasing and decreasing volume with the following works:
0x02 0x03 0xA0 0x55 0x00 0x08 volume up
0x02 0x03 0xA0 0x56 0x00 0x07 volume down.

also the 'volume status request' command does not work as well
(0x02 0x04 0xa0 0x92 0x00 0x01 0xc9)
however the 'volume status data' could be received by sending a 'volume up/down' command so in the worst case I can code it to automate setting single steps to achieve a specific volume.

setting arbitrary volumes works with the stupid songpal api over the ip but it's weird and is not dependable.

Can anyone please help me if it's even possible to set the volume to a specific value over serial?

Yes it is possible to set a volume level via 232.

\x02\x04\xA0\x92\x00\x01\xC9 does request the volume status of zone 1.

\x02\x06\xA0\x52\x00\x01\xA6\x00\x61 does set zone 1 volume to -90dB

This is what the module I use sends.

Your content helped me a lot to take my doubts