What are the options for adding a microphone to the Pimoroni Galactic Unicorn and friends?
The STEMMA QT is i2c and the external resistor pull-ups mean it’s not easy to use the GPIO on those for (push-pull) i2s. All of the ADC capable pins are used on the Unicorn :( I’ve made GPIO27 “dual-purpose” for an analogue input as seen in recent post to Galactic Unicorn as VU meter - #16 by kjw - is that the best/only option?
Is soldering onto the Pi Pico W’s pads on the Unicorn safe?
Try single row sockets (see this post for an image: Raspberry Pi Pico - why does free space show as 848 kB? (and advice on how to add an SD card to an enviro indoor) - #11 by bablokb
Be careful not to solder for too long.
What are your requirements regarding the mic? There are cheap PDM mics around that just need two pins (no adc), but if you really want to record something for playback, you will need to do additional research. I use them for noise-level detection and for this purpose they are fine.
That’s a good idea for pins close to each other (true in this case) as it gives a more general connector. I think a 90 degree one would be needed here to allow the unicorn to still be used on its stand.
For microphones I was looking for something sub 20 USD, easily attached and powered and ideally with existing library support and a reasonably flat response. A nice to have would be some form of control over gain or equivalent. The sparkfun board has an opamp and they make it easy to reduce gain by adding resistors.
I was in manufacturing mode on Monday with a fistful of Galactic Unicorns. I just finished the write-up Instructables: Adding a Microphone to Pi Pico W on Pimoroni Galactic Unicorn
Perfect! Very nice and useful write-up. I also like the images you provide. This could be used as a blueprint for everybody who has to add pins to Pimoroni products (like the Plasma 2040W).