A Class-D amplifier for your Raspberry Pi
Revision 02 has been updated with a cheaper power supply with a wide input range.
The board is designed around the Ti TAS5756 Class D amplifier. It also features an I2C EEPROM, Ti TMP112 I2C temperature sensor, some useful IO connectores, a FET connected to a PWM ouput and a Ti LMZ23603 Simple Switcher module capable of providing 3A on the 5V rail.
For our setup we use Volumio coupled with a little bit of Pyhton code to run everything. First things first, get yourself a running Volumio system by following their manual. Once the board is up and running you can start the configuration needed for the amplifier.
snd-bcm2835entry in the file
/etc/modules, you might want to add
alsamixer, both ANALOGUE and ANALOGUE PLAYBACK BOOST should be set to 100%
#Unmute the AMP echo "17" > /sys/class/gpio/export echo "out" >/sys/class/gpio/gpio17/direction echo "1" >/sys/class/gpio/gpio17/value
You can stack a PCB on the anplifier with 16 extra IO pins. This board is based on the MCP23017 which is a 16 bits I2C IO expander. It has native support in Wiring Pi. You can stack more than one since the expander has multiple address pins. Just make sure you don’t use the same address twice.