Tag Archives: ATmegatron

Atmegatron is an 8-bit mono synth

The miniAtmegatron is a DIY shield kit that will turn your Arduino Uno into an 8-bit synthesizer. 

Back in 2014, Soulsby had introduced an 8-bit synth called Atmegatron which combined the sounds of 1980s home computers with the flexibility and power of a modern-day synthesizer. Now, its creators have relaunched a new and improved version of their sound MIDI machine along with an Arduino Uno shield kit, the miniAtmegatron.


Key features of the ATmega328P powered Atmegatron include 32 waveforms, 15 digital filter types, two ADSR envelopes, one LFO with 16 waveforms, an arpeggiator with 15 patterns and loads of FX including phaser, distortion and Wavecrusher. The gadget comes pre-loaded with 16 preset sounds — ranging from bass to chiptunes — and unlimited expandability via the Atmegatron Librarian software (Mac or PC), which enables it to shape-shift between a drum machine, a duophonic synth and a delay synth.

There are two ways to edit and manage the sounds: six knobs on top along with a value and function knob on the bottom. Turning the left-hand dial selects the parameter to concentrate on, while its value is updated by turning the right. Audio is generated by modulating a PWM output of its built-in AVR processor and filtering off the modulation frequency. The Atmegatron employs analog circuitry in the form of a steep third order Chebyshev filter to maintain the high end, while still filtering off the modulation frequency.

Meanwhile, the Atmegatron’s software utilizes two loops to create its unique tunes. One loop leverages an interrupt to update the PWM output at audio frequencies, with the slower, second loop tasked with the remaining functions (MIDI input, process the wavetable, update LFOs, envelopes, arpeggiators, etc). As expected, the synthesis engine can be completely altered and modded by uploading software to the sleek-looking synth.

What’s more, Soulsby has unveiled the miniAtmegatron, a synthesizer shield kit for the highly-popular Arduino Uno platform. Based on the sound engine of the Atmegatron, the DIY set is comprised of a PCB, all of the necessary electronic components and an instruction manual. It should also noted that the build time will vary (from 30 minutes to an hour) depending on a user’s soldering experience.


The shield is attached to the Arduino and the source code is easily uploaded. Aside from that, the miniAtmegatron features a 3.5mm audio jack for headphones and two LEDs (left shows function, right indicates value) which are controlled by four buttons. Similar to its older sibling, the device boasts a wide range of capabilities. These include a pattern generator, 16 wavetables, 15 digital filter types, two preset envelopes, 16 LFO shapes and speeds, and FX like Wavecrusher and Portamento. Six on-board knobs can be employed to adjust 12 different parameters, such as filter cutoff, distortion, resonance and pitch. The miniAtmegatron can be even be converted into a MIDI instrument by hacking your Arduino Uno, then played via USB.

Sound like something you’d love to play with? Head over to the Atmegatron and miniAtmegatron’s official page here.

Tannin is a DIY MIDI controller

Last week, Bits & Pieces got up close and personal with the Atmegatron, an 8-bit mono synth powered by Atmel’s ATmega328P microcontroller (MCU).

Today, we’re going to be taking a closer look at the Tannin, a DIY MIDI controller built around the Atmel-based Arduino Nano (ATmega328). 

Deisgned by Shantea, the system is equipped with 16 potentiometers, 19 buttons and four LEDs controller.

“It fully supports MIDI Note On/Off and CC messages, including the MIDI In (I’m using that feature in Traktor to control LEDs and set modifiers). It even features experimental MIDI Clock In support,” Shantea explained in a recent HackADay Project post.

“I’ve set it in a way that LEDs blink in sync with that clock, but there’s more work to be done to make it work fully. The buttons also have built-in feature of long press, that is, if you press button for half second (that can easily be defined) it will send another MIDI Note On on another channel (2, regular presses are sent on channel 1). The pots as well send MIDI Note On/Off messages, 6 per pot, depending on their position, with CC messages, of course.”

On the software side, Shantea used The Hairless MIDI to Serial Bridge, routing the messages via virtual MIDI cable software (loopBe30).

“When you match your virtual port in hairless-midi software, the once-serial messages from Arduino will become MIDI messages routed over virtual MIDI cable,” he said. “After that you can easily map your controller to any software which supports MIDI learn.”

In terms of hardware specifics, Tannin’s faceplate is manufactured out of a special plastic board 1.5mm thick (glued to 3mm plexiglas) and houses three PCBs designed in Eagle.

“Two for two groups of potentiometers to get really stable values (I used to connect the pots with wires which often resulted in gibberish values), and they both use ground planes on both sides,” Shantea added. “[Meanwhile], the main PCB [is fitted with the Atmel-based] Arduino, with connectors for two PCBs for pots. Each pot PCB has 4051 chip on it to read potentiometers. Buttons and LEDs [are] connected in a matrix with shared columns.”

Interested in learning more? You can check out HackADay’s introductory blog post here and the project’s official HackADay page here.