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This is a port of the Soulsby Atmegatron 8-bit monophonic synthesizer to the Elektor J2B LPC1343 ARM Cortex-M3 board. The original Atmegatron is based on an 8-bit, 32 KB flash memory ATmega328 and the firmware is available as an open source Arduino sketch. The J2B board has a 32-bit LPC1343 ARM Cortex-M3 processor with 32 KB flash memory.

The Atmegatron has two rotary encoders, eight potentiometers and a pushbutton. Two potentiometers are for volume and bass boost, the others control the synthesizer itself. The J2B board can have up to nine rotary encoders, or eight plus a pushbutton.

The Atmegatron uses a bunch of bi-color LEDs to interface with the user. The J2B can have an LCD.

The Atmegatron uses PWM to produce its sound, the J2B has excellent PWM capabilities.

Based on the previous observations, porting the Atmegatron to the J2B should not be a huge task, which is why I started doing it. The most daunting task was to replace the analog potentiometers by rotary encoders while keeping the same feel.
Two rotary encoders replicate the Atmegatron encoders, six others simulate the potentiometers. The bi-color LEDs are replaced by a 2x16 LCD, but I added two bi-color LEDs to indicate the red/green modes of the synthesizer.

A cool thing of the J2B is its built-in USB capabilities making it possible to update the firmware from any Windows PC simply by copying a file to the board which is seen as an external drive. No programmer needed at all.

PWM capabilities of the LPC1343 are a bit better than those of the ATmega328, which allowed me to increase the sample frequency and gain a bit, making it a 9-bit synthesizer. So, in theory, the sound quality of the J2B synth should be a little better than the Atmegatron.

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Listed2 years ago
ConditionExcellent (Used)
Excellent items are almost entirely free from blemishes and other visual defects and have been played or used with the utmost care.learn more
  • Elektor Labs
  • J2B
  • Clear
  • 2019
Made In
  • Austria

You know you want it

Belleville, NJ, United States
Joined Reverb:2018

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