I've been jamming with other musicians for quite a while, using my old Android tablet as a platform for the lead sheets we use. Occasionally, there are awkward page turns needed so I considered getting a Bluetooth pedal to allow me to change pages without using my hands. These are quite expensive for what they are so I decided to make my own (as have several others here).

I wanted it to be battery-powered and also wanted to print an enclosure on my 3D printer. This project is the result of that.

Step 1: Building the Circuit

As you can see from the schematic above, the circuit is incredibly simple. I used a small piece of strip board (aka veroboard) to hold the two LEDs in their holes in the top cover and hot-glued this in place. The battery and ESP32 are held in place with double-sided sticky foam.

I used a green LED for "Charge" and a red LED for "Not connected" (see the schematic). As these have lower forward voltages than the blue LEDs already on the board, I left the original LEDs in place and just connected across the two existing blue LEDs (one is in the charge circuit, the other is the LED_BUILTIN found on most boards.

As the battery monitor circuit is so simple, I simply soldered the three components in place on the ESP32 and didn't bother using strip board.

Components

The on/off switch was one I had in my parts box and I used the following components to complete the project:

Pedal: https://www.aliexpress.com/item/32801886725.html

ESP32: https://www.aliexpress.com/item/32801886725.html

Battery: https://www.aliexpress.com/item/32801886725.html

Chassis mount USB extension: https://www.ebay.co.uk/itm/232481417132

Step 2: The Code

I used PlatformIO to write the code and program the ESP32. You can use your favourite environment that supports the Arduino platform for ESP32.

The code is pretty trivial as some excellent libraries provide the switch and Bluetooth functionality. I simply added some code to check the battery level and flash the "Not connected" LED when the battery gets low.

The code can be found on Github: https://github.com/raichea/LOLIN32-BT-Page-Turner

Step 3: The Enclosure

I designed the enclosure using Fusion 360 and printed the three parts shown in the pictures. Threaded inserts were used to provide screw fixings for the top cover and the nameplate was glued in place with superglue.

STL files for the enclosure: https://www.thingiverse.com/thing:4880077

Step 4: That's It!

All in all, it's a pretty quick project to put together. The enclosure takes quite a while to print but the circuitry can be put together in an hour or two. Enjoy!