# pico_test_synth Simple board to help make synths with Raspberry Pi Pico and PCM5102 I2S DAC - **Seller:** [todbot synth toys](https://lectronz.com/stores/todbot), Pasadena, California, United States - **Price:** $15.00 (USD, before shipping and taxes) - **Availability:** In stock - **Categories:** Synth, MIDI, Raspberry Pi - **Product page:** https://lectronz.com/products/pico_test_synth ## Links - [Documentation](https://github.com/todbot/pico_test_synth) - [Code](https://github.com/todbot/pico_test_synth) - [Design Files](https://github.com/todbot/pico_test_synth) ## Images ![pico_test_synth](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NTAzMjMsInB1ciI6ImJsb2JfaWQifX0=--5d078e685c2b733346794c9199f4f613d3e9699e/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2025-05-15T18-21-46.402Z-pico_test_synth2_case1_web.jpg) ![pico_test_synth](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NTAzMjQsInB1ciI6ImJsb2JfaWQifX0=--fb48bd3af29566da2617af550bdd5a30e3d6a15f/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2025-05-15T18-21-46.402Z-pico_test_synth2_photo1.jpg) ![pico_test_synth](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NTAzMjUsInB1ciI6ImJsb2JfaWQifX0=--597839d518e49041c45065e075c14ff262dff296/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2023-08-18T04-51-58.123Z-IMG_2496..jpeg) ![pico_test_synth](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NTAzMjYsInB1ciI6ImJsb2JfaWQifX0=--cd7bedf5511b5940d01038fdd49fb8be79bda72b/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2023-08-18T04-51-58.123Z-IMG_2497..jpeg) ## Description #### What is it? A simple [Raspberry Pi Pico RP2040 / Pico 2 RP2350](https://www.raspberrypi.com/documentation/microcontrollers/raspberry-pi-pico.html)-based synth to experiment with [`synthio`](https://todbot.github.io/CircuitPython_Synthio_Tutorial/). This is a partially-assembled PCB with the features: * [PCM5102 I2S DAC](https://todbot.com/blog/2023/05/16/cheap-stereo-line-out-i2s-dac-for-circuitpython-arduino-synths/) footprint for high-quality stereo audio out * Optoisolated MIDI Input via [MIDI TRS-A 3.5mm jack](https://www.perfectcircuit.com/make-noise-0-coast-midi-cable.html) * MIDI output via MIDI TRS-A 3.5mm jack * Two pots for controlling parameters * One switch for controlling parameters * 16 capsense touch buttons for synth triggering * USB MIDI in/out of course too The completely assembled SMD sections of the board are: * TRS MIDI input circuit * TRS MIDI output circuit * Capsense touch circuit The parts you need to add (and solder down) are: * [Raspberry Pi Pico](https://www.raspberrypi.com/documentation/microcontrollers/raspberry-pi-pico.html) **(NOTE: this is the "pico_test_synth2" board; it works with Pico1 & Pico2)** * [PCM5102 I2S Stereo DAC](https://amzn.to/3P4tWuQ) ([more info here](https://todbot.com/blog/2023/05/16/cheap-stereo-line-out-i2s-dac-for-circuitpython-arduino-synths/)) * 0.91" [I2C OLED display](https://amzn.to/3KDmy73) (w/ pins in Gnd/Vcc/SCL/SDA order) * Two 10k potentiometers, 9mm ([example pots](https://amzn.to/3DYYJm5) and [knobs](https://amzn.to/45eLlGO)) * One tact switch, 6mm ([example switch](https://amzn.to/47nJaSN)) * Headers and sockets to mount Pico & display, to taste * [This male & female header kit looks pretty good](https://amzn.to/3qqbtiO), as I prefer to put female headers on the PCB and male headers on the QTPy and OLED display. You may need to trim down your headers to be the right size * Feet. I like M2.5 nylon standoffs (e.g. [M2.5 standoff asst kit](https://amzn.to/45qVjFb)) but feel free to do what you like, including [printing an enclosure](https://www.printables.com/refresh?redirectUrl=%2Fmodel%2F784414-case-for-pico_test_synth-circuitpython-synthesizer)! Differences between `pico_test_synth2` & `pico_test_synth`: - Both use the same components - Both run the same code - Both fit in the same enclosure - `pico_test_synth2` drawn in Kicad, `pico_test_synth` drawn in Eagle - `pico_test_synth2` has square buttons, `pico_test_synth` has round buttons - `pico_test_synth2` works with Pico2 and Pico1 - `pico_test_synth` can only work with Pico1 #### Why did you make it? I wanted a quick and easy platform to test out CircuitPython's synthio and also play with Mozzi. Programs written for [`qtpy_synth`](https://github.com/todbot/qtpy_synth/) will work with this board too with minimal changes. Some programs written specifically for this board: * [TBish](https://github.com/todbot/pico_test_synth/tree/main/circuitpython/tbish/) - a TB303-like synth demo ([video demo](https://www.youtube.com/watch?v=1AflpXbEIno)) * [monosynth1](https://github.com/todbot/pico_test_synth/tree/main/arduino/monosynth1) - a full Moog-like monosynth written in Arduino & Mozzi * [hwtest](https://github.com/todbot/pico_test_synth/tree/main/circuitpython/hwtest/code.py) - test out the hardware with a simple synth ([video demo](https://www.youtube.com/watch?v=9U2Dn7ckdbs)) More code specific for this board coming! #### What makes it special? There aren't that many Pico-based boards that have an I2S audio output, touch inputs and a display. This board does that.