Someone turned their ESP32 into a touch-activated polyphonic synthesizer

Credit: Alxdreee Published Aug 5, 2026, 3:16 AM EDT Simon is a Computer Science BSc graduate who has been writing about technology since 2014, and using Windows machines since 3.1. After working for an indie game studio and acting as the family's go-to technician for all computer issues, he found his passion for writing and decided to use his skill set to write about all things tech. Since beginning his writing career, he has written for many different publications such as WorldStart, Listverse, and MakeTechEasier. However, after finding his home at MakeUseOf in February 2019, he would eventually move on to its sister site, XDA, to bring the latest and greatest in Windows, Linux, and DIY electronics. Sign in to your XDA account Summary This ESP32 touch-capacitive polyphonic synth uses copper strips and MPR121 sensors. It uses custom C++ DSP (filters, envelopes, effects) and runs on ESP32, optimized to avoid crashes. The developer is working to release a tidied-up version of the code, so express your interest to encourage them. We don't often see people creating instruments with their ESP32s, but they are out there. Such is the case with this polyphonic synthesizer, which uses copper strips to register your touch and plays musical notes in response. And while the creator hasn't made the code public just yet, they are looking for people to register their interest. This cool ESP32 touch-based polyphonic synthesizer literally puts music at your fingertips The developer is working hard to release the code Over on the ESP32 subreddit, Alxdreee posted a video of them showing off their polyphonic synthesizer. It looks really simple to play: just prod the copper strips with your fingers, and the ESP32 does all the heavy lifting. It makes some rather nice notes when prodded, and I could definitely see someone making some cool music with it. Here's how Alxdreee describes the project: I used copper ribbon and MPR121 sensors for the custom capacitive interface, and I transmitted the audio via I2S to a PCM5102A DAC. I coded the entire DSP engine from scratch in C++ (including a state-variable filter, envelopes, and a basic effects chain). It was an exciting challenge to optimize it to prevent the ESP32 from crashing. Right now, Alxdreee is waiting on the arrival of an ESP32-S3, which should give them more processing power and a battery to play with. Until then, they're currently sending out feelers to see if people want the source code for this project. People are already filing into the Reddit thread to voice their interest, and it sounds like Alxdreee has already been convinced to tidy up their code and make it public. Be sure to register your own interest if you'd like to encourage them.