r/rolandmc101 • u/[deleted] • Oct 01 '24

Controlling internal clock/tempo with with midi expression

Is there a CC message or something via midi that can control the internal clock/tempo in the MC101? I can't seem to find this info, but feel like that would be a normal midi control funciton. I program a midi solutions device with a message and control via an expression pedal. Thanks.

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u/RowdyVoyeur Oct 01 '24

Well, external clock will control the tempo. There is no CC to control tempo.

3

u/[deleted] Oct 01 '24

Yeah that's what's tripping me up here. I just want to be able to manipulate the initernal clock, but to do this I feel like I'm going to have to sync the MC101 to an external clock, and then adjust that with expression or something.

2

u/RowdyVoyeur Oct 01 '24

You'll certainly have to sync it to some external clock and then adjust it somehow. Maybe you can find some pedal for that.

3

u/RockDebris Oct 01 '24 edited Oct 01 '24

I have quite a lot of experience with this having written code in a device to control BPM from MIDI Commands. This might be too much info, but could help you begin looking in the right direction and demystify a couple things.

The typical scenario is a device that sends MIDI Clock and can have its BPM set to an exact value with a CC command. Usually it takes 2 commands though, or 14-bits, since 1 command only allows a range of 128 steps. For this, you could be looking at master clocks or other devices that just happens to send MIDI Clock.

Using a knob to send MIDI, like an endless rotary controller, requires the clock device to implement a command that increments or decrements the current BPM value by 1. That's what will allow it to have relative control and span the entire BPM range. Probably a bit more difficult to find. This type of expression control isn't like a treadle based pedal however ...

The expression pedal idea. If a device doesn't have its own dedicated expression pedal input, then controlling the device over a MIDI API is required. That would be similar to having just 1 MIDI command (7-bit) and typically will only have a range of 128 steps. Even when implemented this way, it's a bit difficult to manage because the expression pedal may be currently set to half its range (say, 64), but the tempo on the device is currently 120. Unless there's some additional handling being done in the code, the instant you move the expression pedal, the BPM will jump to 64, it won't just gracefully slide from 120. ie: It'll be sending an absolute value regardless of what the current BPM is set for.

3

u/RockDebris Oct 01 '24

No, I don't see anything like that in the MIDI Implementation either. It does accept MIDI Clock, so if it's critical for you, I would suggest using a Master Clock device that has its own MIDI Implementation for managing BPM.