Pivumeter, scroll-phat-hd, shairport-sync and pi zero w without sound card?

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1

I just ran across pivumeter last night and it looked like a great thing. Since I had a scroll-phat-hd already attached to a pi zero w and had shairport-sync running on the pi zero I thought I would give it a try. I was able to build and install pivumeter just fine and the /etc/asound.conf is all set up. However when I have everything set up I get no lights on the scroll-phat-hd.

Shairport-sync is up and running and receiving from iTunes. Originally I shairport-sync set to output to a pipe and I was using python and numpy to do the fft and then sending that to the scroll-phat-hd. It worked but was slow and not quite what I wanted.

I do not have any of the sound cards attached to the pi zero, so there is no sound out. My hope was that I could use just the pi zero and the scroll-phat-hd to create a display. I already have a number of RPIs (2, 3 and zero) that I have used to drive remote speakers with shairport-sync so I’m confident that have that part working.

So here’s my question, will the pivumeter software work on a pi zero if there are no sound cards attached and only the scroll-phat-hd.

The shairport-sync logs show that it is trying to use the scroll-phat-hd device and that shairport-sync believes that it is connecting to it correctly.

For completeness I am running Raspbian Jessie on the Pi Zero and I have tried shairport-sync 3.1.1 and 3.1.2RC0.

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Well I will be damned if I know what I did but after doing some combination of the following I was able to get it to work.

The hardware:

  • Pi Zero W
  • Scroll pHAT HD

The Software:

  • Pivumeter
  • WiringPi (2.44)
  • Shairport-Sync (3.1.2)
  • Raspbian Jessie

I have done the following:

  • Rebuilt each software package (not the OS).
  • Added the shairport-sync user to the i2c group so it has permission to write to the Scroll pHAT HD.
  • Created a home directory for the shairport-sync user and copied the .asoundrc file in the pivumeter source to it.
  • And finally started fiddling with i2cdetect and then i2cdump to see what, if any data was getting to the Scroll pHAT HD.

As soon as I started using i2cdump the Scroll pHAT HD fired up and started displaying the FFT of the audio that I was streaming from iTunes. I’m going to try and recreate the steps to see if I can figure out what combination did the trick.

If anyone can spot the key points in here I’d love to know.

At least my original question was answered. Yes, you can use the Scroll pHAT HD on a Pi Zero W to visualize audio without having any sort of sound card present.