are there some ideas for turning on/off an external amplifier by a signal generated from the V3 board? It should be out of the box and without using the APC workbench tool.
What i have found, is that the VCC_5V pin of the I2S connector seems to be not directly connected to the 5V rail of the board. Is this a switched voltage output?
Maybe the GPIO’s of the board have a defined state after power-on or while playing music?
Thanks for your help!
not sure if this helps but I already replied to a similar question
Pin for 220v relay on arylic V3 pro - #2 by Nobu.
the manual online:
3.3V instead of 5v… but it’s switched on/of with the remote control.
thanks, i found that while searching for a solution. So this 3.3V pin is switched on while the board is active and after powering off (by the remote or command over http or UART) the pin is low?
That would be helpful for generally put the amp into standby when the unit is not in use. I also found a solution with one of the two GPIO which goes low after a while when the music has stopped, but this will only function with the help of the APC workbench tool. For multiroom applications, the boards are all powered on because no remote control is used (only the app is used), so in this case the switched 3.3V will not help to get the amplifier down. So the GPIO solution with the tool would be the best - my hope was that there is a solution that works out of the box.
Yes this pin follows the power status of the board, at least with the current MCU firmware. (this probably is the GPIO pin you are mentioning, on the 4 pin connector)
I understand your concern, I wasn’t thinking of the multi-room configuration. But your remark is legitimate, it would be useful to turn on/off all boards from the remote / power switch or with a single API command on the master. I didn’t investigate this option & I do not have the ACP tool.
Is the other pin you are mentioning going low/high after music is muted on the 7 pin connector (I2S / SPDIF) ? if so I looked with the oscilloscope, indeed the I2S or SPDIF signal go low when no music is played, this to avoid glitches on the audio output.
But this is not a DC signal it’s a digital stream oscillating between 0 and approx 5V at several Mhz. You could use it with a simple stream detector (diode+ capacitor + resistance) which output would go high when the stream is present and low when it’s not. And with a more sophisticated circuit you could have a timer to turn off the amp so that it doesn’t always go on and off when changing music or between tracks. Also this would mean when turning on the devices there would be the set up time of the amp that would need to be taken into account.
I looked if the API command ‘mute all’ I have in my set of commands was operating, this would have been another way of turning all off, but it seems it doesn’t… :-(.
So for now, no real true solution…
thanks a lot for your very helpful input!
That is exactly what i have planned to do if there is no out of the box solution - looking for a signal like SPDIF and place an RC circuit behind to measure if there is an active audio signal. Together with an anti-plop circuit to avoid noise with powering/unpowering the whole unit this should be a good solution.
I am designing an I2S amplifier in the meantime, on this PCB i will add an extra µC to do all the jobs above. Maybe the µC will be used for detecting mute status via UART, i will do some tests if this would work too. The final result will be an very efficiency stand-alone solution with best possible audio quality. The pcb will supply the V3Pro too with power, so a single 24V supply is sufficient. The 24V rail will get inrush current control, polarity protection and a low noise LDO behind to get rid of the ripple.
Thx for the update.
let us know how it’s progressing, especially the I2S amp you’re designing. (architecture, chips etc…)
yes of course…i will keep you updated.