Cvpal frequency responses to inputs

Hi guys, having pretty much exhausted my bank account now buying modules cases etc… I’ve decided to try and get a few of the things I had in mind by writing lemur controllers specifically for the Cvpal. The usual are in there like clock dividers etc… But I am interested in the bonus oscillator operation mode.

As I take it, the bonus square wave is generated by a fast cycling trigger pulse so does anyone know if in the cc mode or more sensibly the gate / trigger modes if sending a trigger via midi at a high enough rate would be possible to get any output to oscillate? I imagine cpu clock is a limit of the software here as stability may cause the iPad to go a little crazy, but it would be cool to know if anyone had achieved a similar thing bursting gates to it.

I’ll also try and share any patches for I write for the lemur as they come, as I would expect they will come in handy to others.

Failing that… I have the horrible suspicion I will need to get a pic burner and start getting deeper into the core of the wee guy.


The “bonus oscillator mode” uses the digital timer integrated in the Attiny - no CPU is involved at all (just hardware which is part of the chip), and it’s rather accurate.

It seems to me that you’re be interested in creating something similar (for which reason?) by sending pulses at a very fast rate. You’ll quickly hit the following limit: USB MIDI is polled, which causes all events to be quantized on a 1ms grid. For example if you try sending pulses 24.5ms apart, they’ll either be distant by 24ms or 25ms. And there’s probably even more jitter on the MIDI / USB-MIDI driver side.

The CVpal is quite responsive though, you’ll hit limitations on the host side before :slight_smile:

CVpal uses an Atmel chip, doesn’t it? So you’ll need an AVR programmer, not a PICkit. Worth spending $40 buying the official Atmel programmer as recommended by Olivier, IMHO - it just works. The CVpal source code is all in one file (maybe a header file too), so is easy to get your head around. I have a CVpal which I don’t need for MIDI-to-CV any more, so am keen to wxplore what else it could be used for.

Thanks guys.

I had the suspicion that USB would be the main issues. Just starting to read the lemur code guide just now to start piecing things together.

Looks like getting a programmer when I get paid is a good plan maybe another cv pal too break.