While we're at this one other thing that had occurred to me was that supply voltages CAN be variable. This mean's you'll require two pins for SPI, and two pins to control which chip is receiving. These pins (Active low) determine which chip will receive the messages you send. If you plan to have multiple DAC's on the SPI bus, you'll have to hookup the CS (chip select) pins to the arduino. (31.25k baud) Even saturating the midi bus (~2000 note on/offs per second) gives you half a millisecond to respond, which is plenty to set an output (a few microseconds) and send a message over SPI. The biggest bottleneck you'll have is the midi data rate. You'd be surprised how much you can do with a 16mHz micro. Most people would just use a transistor switch, but if you have a spare amp, why not? However, if you wish to create a stronger gate signal, you definitely could use the other op-amp in the package to boost the gate signal. The second circuit I intended to be used with your DAC's output (MCP4921/4922) to provide the gain to change the range from 0.5v to 0.10v.

The first circuit is all you need (unless you really try hard) to protect the Arduino's digital outputs (your gate signals). Gates/triggers seem to be a non-issue since I believe most things will trigger at 5V, but if not then I'll need to apply gain to those signals as well, but at least it's a simple digitalWrite() call.Īh, I should have been more clear. My original thought would be to map MIDI CC values to straight up CV outputs and/or gate triggers. Everything is oriented around a 0-5V scale, but for pitch you want 0-10V ideally.is this as simple as just a short amplifier stage after the DAC?Īny other suggestions/ideas? I'm currently prototyping with a Mega 2560 and SparkFun MIDI shield (waiting for both of these to arrive actually, so I can think about the rest of this stuff while I wait). But they seem to solve the problem of resolution adequately.Ĥ. 12-bit DACs are holy-shit-OMG-expensive ($35+ in Q1). AnalogWrite() is limited to 8-bit resolution, which can result in noticeable stepping.ģ. You want something much smoother, and even a simple LPF over it doesn't seem to be enough (from what I've read).Ģ. The Arduino has PWM outputs, which is not what you want driving a modular's CV inputs. I originally thought that doing an Arduino based MIDI->CV would be relatively easy, but as it turns out there are a lot of details that are making it less than straightforward.ġ.

Arduino mega 2560 dac pins