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Miniamp and SPI interface

Martin Leopold

June 27, 2024 22:32

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Hi,

I've been trying to set up a Raspberry Pi Zero 2 with a MiniAmp and an SPI based RFID reader (think Phoniebox). I can make each work fine individually, but not at the same time and I can't figure out why. As far as I can tell from the documentation the GPIO's should not be overlapping.

I have enabled the MiniAmp with the following entry in /boot/config.txt. This works, and the amp outputs audio.

dtoverlay=hifiberry-dac

Next I enable SPI, but as soon as I do that the volume goes to 0.

dtparam=spi=on

Alternatively I've tried only using one CS line, but the result is the same.

dtoverlay=spi0-1cs

The manual mentions GPIO16 and GPIO26 being used to mute/power-off, but I haven't used those GPIO's for any purpose. I'm not sure what to debug next, can you hellp me out?

Br,

Martin

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2 comments

• 0
  
  Martin Leopold July 02, 2024 20:50

  Hi,

  Debugging my problem a bit further, but without finding a solution. I'm using mopidy as a player on a (raspberry pi OS Bullseye), but with the extension mopidy-pummeluff for reading tags. And the problem seems to start when enabling that extension.

  Booting the pi with SPI and hifiberry-dac enabled works just fine when playing from the command line (as well as reading an RFID tag through a python script), and playing with mopidy without the extension also works just fine. But as soon as I start mopidy with the mopidy-pummeluff extension I hear no audible output.

  I've tried checking the GPIO16 and GPIO26 status before and after, but I see no change in the state - even though they read as high for some reason (and forcing them low as output pins doesn't change the audio output)

  raspi-gio get
  ...
  GPIO 16: level=1 fsel=0 func=INPUT
  GPIO 26: level=1 fsel=0 func=INPUT

  So it would seem that there is nothing wrong with the hifiberry-miniamp or the Pi, but I still don't have a clue why my player doesn't play. Any ideas?

  Br,

  Martin

• 0
  
  Martin Leopold July 03, 2024 06:41

  Hi,

  Got it - turns out mopidy-pummeluff also initializes a set of other GPIO pins apart from the SPI ones (for button interface). I missed that, so that's what's been acting up.

  Anyway, all good - hifiberry-miniamp plays like a champ.

  - Martin