Why no AOUT based on the MCP4822?

[m00dawg]

I've been looking at MIDI -> CV again. While I like the Mutant Brain Eurorack module (and Polyend's MIDI->CV looks amazing), I built my own custom expandable case (which by the way is available in kit form for those interested) and am looking at some of the modules that have external I/O and seeing what I can do to route those to the back. Having a MIDI cable always connected to the front of my rack feels out of place, and it gets in the way where it can just live along the back of the rack (that's where the power is already).

 

Mutable Instruments' CVPal, along with some others, use the MCP4822 chip. It's 2 channel but has an internal voltage reference and it's 1/3rd the price of the MAX525. Buying 2 still is only 2/3rd's the price of a 525. The CVPal has a calibration procedure, similar to what I was thinking. I was actually going to use a LUT for all the notes so each note has a specific calibrated value (CVPal tests at the first and 7th notes of the octave to derive offsets).

 

Anyways I'm flying off the rails a bit I guess. The point was, curious why no AOUT_4822 exists since that seems like a favorable option to the AOUT_LC?

For my application, I'll probably end up on a Teensy and using the Arduino platform but the MBCV project has _a ton_ more going for it by comparison (though it doesn't easily fit inside a Eurorack format I don't think?)

[latigid on]

MCP4922 was indeed developed for, so it could be a good start? It doesn't look like it has a serial output, so if you need more than 2 channels you need to run them in parallel with /CS lines. That is a good advantage of MAX525/MAX5500 or the TLV chip.

The midiphy euroceiver has an IDC header that may be attached to a "crimpable" DB-25 connector. So that way it can sit in the back of the case if you like. 

 

[m00dawg]

Both the 4922 and 525 use SPI though yeah? 525 has more channels though certainly. Going SMD there's options for 8 channels even. It's good point though I hadn't though if/how SPI works on the MidiBox platform and which pins are available for the chip-select. My Mutant Brain has 4 CVs along with 12 triggers, which is usually plenty for me, though designing something with a few more CVs could be nice. I had thought of how I might go about making a base module (which houses the uC) and then having modules you can add which have an addition DAC and Op-amp and perhaps some sort of shift-register to provide a set of gates with it too.

Good point about the receiver though, I hadn't thought of that. Actually I think I could just mount that whole module to the back of the case and call it good? And/or the MIDI in/out's if I can internally route them over to the CV modules. I'll have to look again at all the Midiphy options there as I know they're fairly numerous!