14-bit MIDI CC weirdness (25SL, Live & a dash of Bome's)

robbmasters · Post by **robbmasters** » Sat Mar 03, 2007 8:02 pm

If I use 7-bit CC values, or relative values, my 25SL talks to Live just fine.

However, I have a rotary encoder on my 25SL sending 14-bit values on CC24, and Live seems to think it's sending both 14-bit values on CC24 and 7-bit values on CC56!

I only noticed as CC24 was mapped to tempo and CC56 to a filter frequency, so I was getting some very odd effects! (This was without Bome's MIDI Translator running at all.)

If I start Bome's (with an empty preset) and use the Capture MIDI function to monitor the MIDI input, Bome's seems to think the 25SL is sending 7-bit values on CC56* (with each value invariably being sent twice). When the encoder gets to 128, Bome's goes back to zero.

I don't really understand how 14-bit values work in terms of MIDI data. So there's possibly a very simple explanation to what's happening. But I've no idea what it is! Maybe I don't need to understand it. But I do need to know how to avoid it...

Do 14-bit CCs use another CC for the other 7-bits? If so, I'll need to avoid mapping that CC to anything else - so how do I know which one it will use?

Or is something seriously messed up? A reboot didn't help...

I recently installed the V3 OS on my 25SL. But that doesn't seem to be the problems as I went back to v2.5 and it was exactly the same...

Can anyone help?

(* Actually Bome's says Controller 57. But it always seems to give values that are one higher than Live or the 25SL, so I've called it Controller 56 for simplicity!)

johnpitcairn · Post by **johnpitcairn** » Sun Mar 04, 2007 9:44 pm

CCs are a 7-bit message. A "14-bit CC" uses two CC messages - MSB on the base CC number, and LSB on a CC number 32 higher, even if the LSB is zero.

robbmasters · Post by **robbmasters** » Sun Mar 04, 2007 10:09 pm

Thanks for the reply. From what I'd read online, I'd got the impression that both messages were sent on the same CC, i.e. "CCnn MSB CCnn LSB".

But maybe that's SysEx only (or even device specific SysEx), as that doesn't seem to be what I'm getting. I can only assume I'm actually getting "CCnn MSB CCnn+32 LSB" (but I don't know why Bome's doesn't show the first half).

If I'm right then, if I send 14 bit values on CCnn, I need to avoid using CCnn+32 for something else. Certainly the 14-bit values that are part of the standard MIDI controller set (bank select, modulation, breath control, etc.) do seem to use CCs that are 32 controllers apart (0 and 32, 1 and 33, 2 and 34 respectively).

Is that right?

robbmasters · Post by **robbmasters** » Mon Mar 05, 2007 2:24 pm

I emailed Novation after my original post here. Got a reply this morning to say:

It is kind of taken as standard with MIDI CCs that the first 32 (0-31) can work as 14-bit control messages by using the next 32 CC numbers (32-63) as the LSBs. Consequently if you set an encoder to send CC0 messages in 14-bit mode it will send CC0 messages for the MSB and CC32 messages for the LSB. CC0 is generally used for coarse bank select and CC32 id generally used for fine bank select.

Basically what John said (thanks again, John). But it's nice to get quick and comprehensive support from Novation.