Using a amp or DAC with Controlblock ?

weyland

Hi,

I'm planning a bartop build with a Controlblock. I'd also like to use a proper DAC + amplifirer (Pi-DigiAMP+ or JustBoom Amp HAT ) but these boards need GPIO pins 3 & 5, already used by the ControlBlock.
So is there a way to use the ControlBlock with an amplifier, or do I have to use a DAC (such as the Pimoroni pHAT DAC) then connected to an external amplifier ?

Thanks

slartibartfast

@weyland I'm trying to get a generic Hifiberry DacPlus to work but it seems as there is a conflict somewhere - no sound comes out and i've checked the board on its own (without the controlblock plugged in and it works ok)

petrockblog

I do not have any experience with the DACs that you mention above, but you can find the used pins for the ControlBlock here. The used pins are:

3.3V (pin 1)
5V (pin 2)
GPIO 17 (pin 11)
GPIO 18 (pin 12)
MOSI (pin 19)
MISO (pin 21)
SCLK (pin 23)
CE0 (pin 24)

ortsac

I also do not have experience with the DAC boards mentioned here. As you can see from what @petrockblog listed, the pins used are for power and service communication between Pi and the ControlBlock. It uses very little GPIO pins.
To understand where your problem lies, could you provide GPIO pins that are used by DAC boards?
Does the DAC amplifier play well with Retropie without the ControlBlock connected?

ortsac

@slartibartfast Per Hifiberry documentation here are the reserve GPIO pins that cannot be used for any purpose:

HiFiBerry DAC+, Digi+ and Amp+

GPIO2-3 (pins 3 and 5) are used by our products for configuration. If you are experienced with I2C, you might add other slave devices. If you a a novice, we don’t recommend this at all.
GPIOs 18-21 (pins 12, 35, 38 and 40) are used for the sound interface. You can’t use them for any other purpose.

On the HiFiBerry Digi+, GPIO16 is also reserved.

As you can see, both the Hifiberry and ControlBlock use GPIO 18 (pin 12) and that could be where your problem is.

weyland

Wow, It's been a while... So thanks for your answers: I will park my 'dedicated DAC' idea and simply pull the audio from the HDMI!