2 phats at once


#1

I want to run an automation phat and a speaker phat on the same Pi zero.
I know that they both use a few GPIO lines in common, but I wondered if there might be a workaround. Or would it be possible to ‘bend a bit of code’ to make it work?
Please don’t suggest a bluetooth speaker - I’ve tried that several times over with several different approaches, all of which fail.
I’m not much of a programmer and I can barely handle linux, but if the instructions are simple I should manage.
Any thought would be appreciated.
Thanks.


#2

Automation pHAT’s Input #3 clashes with the I2S clock for Speaker pHAT, but otherwise you should be okay. You can test combinations at: https://pinout.xyz/phatstack

If you can cut/move/rewire or otherwise avoid connecting Automation pHAT’s input one, then you should be fine.

That said, since it’s an input… you might be okay. It depends what the output of the Darlington Array is doing and whether that interferes with the I2S clock (pulls it high or low when you don’t want it to)

There’s no software fix, but a craft knife or soldering tweak might help.


#3

Thanks, thats exactly what I needed.
I’ve ordered a FullPhat, so I’ll be able to ‘hack’ that.


#4

Been thinking about this again. Is there going to still be a clash, as Automationphat will define it as an input, but speakerphat will define it otherwise. Will it depend on which one is called last as to its definition?
Another question. Is there a significant dc current running through the speaker? After running it for an hour or so, when I touched the magent part of the speaker it was VERY hot.
Is this normal?


#5

I believe Automation pHAT will define the GPIO stage as an input, but since this is behind the multiplexer that’s used to connect that pin to the I2S hardware, it will have no effect.

Speaker pHAT getting hot is an issue with how ALSA talks to our DAC when idle- we’ve rolled out a hardware fix for this, but for early boards you should use the Pulse Audio setup created by our one-line-installer which prevents it from happening.


#6

Thanks. Let’s hope disbling that input works.

As for speaker phat, I’m sure I used the one line installer. Anyway I’m using pygame mixer and that doesn’t seem to give the problem.


#7

I’ve used the one line installer, but as I’ve just burned my finger on the speaker - and it hurts - I can tell you that this doesn’t work.
Apart from that, when running my program, I get significant audio interference when I run the automationhat or camera routines. Any idea how to stop that?


#8

You could try cloning down the Automation HAT library-

git clone https://github.com/pimoroni/automation-hat

And changing the pin defined here for an unused one: https://github.com/pimoroni/automation-hat/blob/a709aacd071260a566b7ebe137c38fac1207400b/library/automationhat/init.py#L21

Then install from the library folder with sudo python setup.py install

The camera setup should not be causing audio distortion, though, it might perhaps be a CPU load issue rather than a GPIO one.


#9

Oh and also, please drop me a PM with an address so I can send you a replacement Speaker pHAT.


#10

Thanks gadgetoid, but I’ve moved away from Speaker pHAT. With all the trouble I’ve had trying to get audio out of the Pi Zero, I decided to buy a Pi 3B instead. But thanks very much for the offer.