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Step 5: Phat Audio

Picture of Phat Audio
Phatbeatpinout.png
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I knew that audio would be important for this project, as there's no point talking to the postman remotely if he can't hear you properly! I decided to go with the Pimoroni pHAT BEAT, as I had one handy - though in some ways that was slightly overkill for this project.

I only really needed a single mono output for the doorbell, but the pHAT BEAT offered stereo output to two speakers, as well as a nice LED VU meter.

There's not much to say about the installation & setup, I followed the instructions and was up & running in no time, listening to the hypnotic "Front Left, Front Right" of the test file.

The only complication of using the pHAT for the audio was that it would sit on all of the pins on the GPIO header - and I needed some of these to connect up the doorbell button and LED. To get around this I added in a pico hat hack3r - found in a party bag from last year's Raspberry Fields. It's a tiny but very handy board that essentially splits the GPIO output in two, letting you connect a HAT while still exposing a full set of GPIO pins. Though this is great you do have to be careful not to conflict with pins already in use by the HAT, so I double-checked pinout.xyz and decided on the following:

Doorbell button - GPIO22 (Pin 15) and 3v3 next door (Pin 17)
Notification LED - Positive to GPIO9 (Pin 21, via a resistor), Negative to GND at Pin 25

With the webcam, audio, button and LED connected up and working, I now had a working video doorbell - albeit spread out over an entire workbench. Next I needed to think about how it would be used and what it would look like.