iqaudio pi-dac+ and GPIO

I’ve just bought a pi-dac+ and a RPI B+.

  1. As far as I understood ALL gpio pin can be populated on the top of the pi-dac+ (by adding/soldering a pin header)

Does this is correct ?
(in current setup (RPI B and USB-i2S DAC) I have LCD, temp & IR sensors connected to the GPIO and I want to be sure that I can connect them on the “populated” gpio)

  1. is there any “populated” GPIO pin that CANNOT be used for “sth else” (i.e. pins which are reserved for the iqaudio dac+ to work)




All of that is greek to me. However the updated documentation for DAC+ has some stuff about gpio pins. … IO_Doc.pdf

The Pi-DAC+ uses the following signals:

  • I2S
  • I2C
  • GPIO 22 (This is used to mute the Pi-AMP+ if fitted)

Others you can use.

We have previously recommended the following allocations (for compatibility with the older Pi-DAC)

  • GPIO 23/24 for Rotary Encoder
  • GPIO 25 for IR Sensor

Hope that helps,

Hi Gordon,
Thanks for prompt reply

Could you be a bit more specific ?
i.e which pins are exactly used by the PI-DAC+ (including power (5 and or 3V) and ground pin(s))

I will not plug your AMP+ and used your code for rotary encoder and IR remote —> can I still use the GPIO 22, 23, 24, 25 for others purposed ?

The Pi-DAC/Pi-DAC+ uses the following signals.


all of the above (other than I2S) you can use or your own purposes. The GPIO pins are not used for the general operation of the Pi-DAC/DAC+

The user docs list the pin numbers for the Pi-DAC IIRC.

Best regards,


Just got my RPI-DAC+ :slight_smile:
I’ve soldered the pin header (for the accessing the GPIO pins once the DAC is placed on the RPI-B+) and I checked on a multimeter each GPIO pin

Everything was fine except for the following pins :
GPIO-04 (pin 7) - GPIO GCLK

GPIO-14 (pin 8) - TXD0
GPIO-15 (pin 10) - RXD0

GPIO-08 (pin 24) - SPI-CE0-N
GPIO-07 (pin 26) - SPI-CE1-N

from this page ( I understood the following:

  • At reset only pins GPIO 14 & 15 are assigned to the alternate function UART (universal asynchronous receiver/transmitter)

I noticed, by looking on the top of the DAC that this pins are not linked to the “soldered” pin header, is there any particular reason for not connecting this pins ?


It’s just the way we laid out the pcb board. I’ll update the user docs to make this clearer.