Voltage Controlled DAD Envelope

Motivation

This is the first envelope generator of a series built around the Atmel AVR 328p and the MCP4921. Generates a delay/attack/decay envelope on rising edge of gate. Further gates ignored until end of decay is finished (EOC). Delay/attack/decay time is manually and voltage controllable. Goes up to 500Hz when looping. Gate is polled every loop. CV input parameters are read with timer0 interrupt ISR (TIMER0_OVF_vect). Delay-, attack-, decay- and EOC LED and outputs are switched. Software driven. The software is kept as simple as possible, so you can easily adapt it to your needs. Status signaled with LED. The attack and decay timing is determined with tables, so you can easily adapt the timing to your needs as well.

Specs and features

• Delay, attack, decay envelope
• All parameters voltage controlled
• Triggers at +3V
• Triggers at any waveform
• Goes up to 500Hz when looping
• Software driven
• Buffered outputs
• Overvoltage protected inputs
• Status signaled by LED
• Status outputs
• Runs on +/-15V and +/-12V
• Power consumption around 35mA positive, 10mA negative rail

Implementation

Schematic

Yellow: Gate; Blue: Envelope; Purple: Attack on; Green: Decay on; Delay: None

Yellow: Gate; Blue: Envelope; Purple: Delay on; Green: EOC on; Attack on, decay on, not shown

Yellow: Decay on ; Blue: Envelope; Purple: Attack on; Green: Decay on

Blue: Envelope; Purple: Attack on; Green: Decay on; Decay: None

Description:

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Calibration

• None

Top

Building hints

• Don't forget to set the correct fuses for the Atmel AVR 328p
• The DAD ENV uses the same hardware as the DAR ENV. Don't let the naming of the hardware confuse you. The difference is in the software.

Special parts

• None

Download

Voltage Controlled DAD Envelope control board documentation download
Voltage Controlled DAD Envelope control board Gerber files download
Voltage Controlled DAD Envelope main board documentation download
Voltage Controlled DAD Envelope main board Gerber files download
Voltage Controlled DAD Envelope *.fpd file
Voltage Controlled DAD Envelope Software

The software is kept as simple as possible, so you can easily adapt it to your needs. The attack and decay timing is determined with tables, so you can easily adapt the timing to your needs as well.