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What is it?

This is a bare circuit board designed to accept three standard 6mm through-hole buttons and a 12mm piezo buzzer. It's designed for simple and/or low power applications where you don't want to deal with a GPIO expander or a speaker amplifier.

This board gives you three active-low inputs on (typical numbering) pins 5, 6 and 9, and a piezo buzzer on pins 10 and 11. It is compatible with most Feather boards (though notably, NOT the Feather HUZZAH ESP8266).

In the bag:

• 1x Button / Buzzer PCB
• 1x 40-pin 0.1" pin header strip (if selected)

Note that you will need additional parts to assemble this design, although honestly it's likely you already have some of these parts sitting around:

• 3x 6mm tactile button (this is a pack of 10)
• 1x PS1240 piezo buzzer
• OPTIONAL: 1x 6mm slim tactile button as a reset button

Why did you make it?

I made this board largely to pair with the LCD FeatherWing: many of the projects I wanted to do required some simple button inputs and audible feedback. The parts for this are readily available, but I didn't want to wire up a FeatherWing Proto by hand every time. This is a simple board that costs the same as a FeatherWing Proto, but it's all set up for this specific use case.

What makes it special?

The Button / Buzzer FeatherWing is a very simple design, but a great deal of thought has been put into it.

Since the board consists solely of passive components, this FeatherWing's quiescent current draw is effectively zero. It's also designed for CircuitPython deep sleep:

• When paired with a board like the ESP32-S3 Feather, any of the buttons can wake the device from deep sleep.
• When paired with a Feather M4 board, an available solder jumper allows you to connect button 0 to pin A0, allowing Button A to wake the board from deep sleep. (this board only has one deep sleep input)

For basic use of the buzzer, the BUZZ- pin can be set low, and the BUZZ+ pin fed a square wave at the frequency of the tone you wish to sound. This will produce a very respectable beep, especially near the buzzer's resonant frequency of 4 KHz.

For louder volume, the BUZZ- and BUZZ+ pins can be driven differentially: BUZZ- low when BUZZ+ is high, and vice versa. This increases the buzzer's peak-to-peak voltage to 6.6V, which is great for loud alarms!

Finally there is a footprint available for a reset button at the top left. If you are using a wing doubler or tripler, you may already have a Reset button available; if on the other hand you are stacking this directly atop a Feather, this button ensures that you still have the ability to reset the board.

It's a simple design, but if you need three buttons and a buzzer, you can put them on this board and it'll "just work".