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10-Dec-2020

12. Controlling the DigiAMP+ Mute / Un-mute

The DigiAMP+ MUTE state is toggled by GPIO22 on the Raspberry Pi. The latest IQaudio device tree

supports the unmute of the DigiAMP+ through additional parameters (from Raspbian 4.4.14+

onwards)

…

dtoverlay=iqaudio-dacplus,unmute_amp

"one-shot" unmute when kernel module loads.

dtoverlay=iqaudio-dacplus,auto_mute_amp

Unmute amp when ALSA device opened by a client. Mute, with 5 second delay

when ALSA device closed. (Re-opening the device within the 5 second close

window, will cancel mute.)

If you do not want to control Mute state through device tree then you can also script your own

solution. The information below may be useful.

# The amp will startup MUTED

# to unmute the amp.

pi@raspberrypi ~ $ sudo sh -c "echo 22 > /sys/class/gpio/export"

pi@raspberrypi ~ $ sudo sh -c "echo out >/sys/class/gpio/gpio22/direction"

pi@raspberrypi ~ $ sudo sh -c "echo 1 >/sys/class/gpio/gpio22/value"

# to mute the amp once more...

pi@raspberrypi ~ $ sudo sh -c "echo 0 >/sys/class/gpio/gpio22/value"

If you already use WiringPi:

# If using WiringPi - to unmute the amp

gpio mode 3 out

gpio write 3 1

# to mute once more

gpio write 3 0