Micro:Bit Gets Pseudo-Polyphonic Sound With Neat Hack

November 18, 2025 by Lewin Day 4 Comments

The Micro:bit is a fun microcontroller development platform, designed specifically for educational use. Out of the box, it’s got a pretty basic sound output feature that can play a single note at a time. However, if you’re willing to get a bit tricky, you can do some pseudo-polyphonic stuff as [microbit-noob] explains.

The trick to polyphony in a monophonic world? Rapidly alternating between the different notes you want to be playing at the same time. Do this fast enough and it feels like they’re playing together rather than seperately. [microbit-noob] demonstrates how to implement this with a simple function coded for the Micro:bit. Otherwise, it uses the completely stock sound hardware. However, the IR receiver is added to the device in order to allow a simple remote control to be used to command the notes desired, along with some extra tactile buttons to add further control.

Is it chiptune? Well, it’s a chip, playing a tune, so yes. Even if it is through a tiny speaker stuck to the PCB. In any case, if you’re trying to get some better bleeps and bloops out of the Micro:bit, this is a great place to start. If you’ve got other hacks for Britain’s educational little board, let us know on the tipsline!

Pico Makes A So-So Keyboard Neat-O

December 9, 2023 by Kristina Panos 9 Comments

When someone gives you a crappy little toy keyboard, what can you do? Sadly plunk on the thing one note at a time? Well yes, but that’s not going to get you on Hackaday. Do what [Turi] did and give that thing a complete overhaul.

[Turi] threw away the original controller board, keeping only the keys, buttons, case, speaker, and a little bit of the original powder yellow enclosure. The Picophonica’s new brain is, you guessed it, a Raspberry Pi Pico. This enables [Turi] to use [Ryo Ishigaki]’s pico_synth_ex synthesizer and introduce MIDI out via USB-C.

The new engine does things that little keyboard could never have dreamed of originally, especially considering it wasn’t even polyphonic. Those fourteen white buttons now control things like sustain, cutoff, LFO rate, decay, and so on. Now it sounds great!

Be sure to check out the brief build video after the break. Excluding drums, the soundtrack was made entirely on the Picophonica.

Of course, Picos aren’t just good for musical keyboards. Use one to convert an old proprietary keyboard to PS/2, or create your own.

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Polyphonic FM Synthesizer Uses ARM

December 14, 2015 by Al Williams 13 Comments

There seems to be a direct correlation between musicians and people who can program. Even programmers who don’t play an instrument often have a profound appreciation of music and so we see quite a few musical projects pop up. [Ihsan Kehribar’s] latest project is a good example. He married an STM32F031 ARM development board, an audio codec, and a simple op amp filter to make a playable MIDI instrument. Of course, it is hard to appreciate a music project from a picture, but if you want to listen to the results, there’s always Soundcloud.

He’d started the project using an 8-bit micro, but ran into some limitations. He switched to an STM32F031, which is a low-end ARM Cortex M0 chip. [Ihsan] mentions that he could have used the DSP instructions built into larger ARM chips, but he wanted to keep the project done on minimal hardware. The audio CODEC chip is from Cirrus Logic (a WM8524), and it produces two output channels at 192 kHz. As an unexpected benefit, the CODEC uses a charge pump to generate a negative voltage (much like a MAX232 does) and [Ihsan] was able to tap that voltage to provide the op-amps in the audio filter with a negative supply rail.

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