Controller Circuit

4bitsynth is 4 bit MIDI-controlled digital synthesizer inspired by the NES. The project is built around Atmel AVR ATMega48 The digital output is put through an R-2R resistor ladder to get the analog waveform. It has three type output : Square wave, Triangle wave and noise.


Project Features Detail :

Triangle

• One volume (uses up/down counter)
• Pitch sweep (up/down, optional looping)
• Standard pitch bend
• Fine pitch bend

Square

• Three duty cycles: 12.5%, 25%, 50%
• Volume decay (optional looping)
• Pitch sweep (up/down, optional looping)
• Standard Pitch bend
• Fine pitch bend

Noise

• Two modes: 93-bit and 32k (think NES)
• Volume decay (optional looping)
• Pitch sweep (up/down, optional looping)
• Standard pitch bend
• Fine pitch bend