I'm working on a sequencer (analog + MIDI) for Arduino and I've got the MIDI and trigger output (5V pulses) done,but now I need to start on the control voltage. I need to generate a multiple (6+) -10 to 10V signals (ideally with software based scale and bias) to control a modular synthesizer. PWM won't be sufficient due to resolution issues, I'd like at least 12-bits of resolution. I'm comfortable interfacing over SPI to a multichannel 12-bit DAC such as the Microchip models.However, I'm uncertain what type of circuit I'd need to provide amplification, scale, and biase on the output from the Microchip (which is presumably 0-5V). This is complicated by the need for bipolar output and I'd ideally have a single power supply providing power to the Arduino and the amplification section.Any suggestions for a simple circuit I could implement?
An improvement to that circuit would use a precision, low-drift 2.5V voltage reference (rather than a pair of resistors between Vcc and ground) to generate the 2.5V input to the op-amp.