Spin Semiconductor

I had a thought - if you hooked up a momentary switch to a POT pin, could you use that input to trigger tap tempo? This might sound real stupid but I thought it might work. You setup a ramp lfo to sweep very slowly, like 1hz, or whatever your maximum delay time would be. When you see the switch close (forcing POT to zero,) you JAM the lfo to the start value. When it sees the POT go to zero again, you read the value of the lfo into a register and JAM again. Every time the POT zeroes, you just average the value of the LFO and JAM again. The LFO value gets multiplied by some constant to set the delay time correctly. The only problem I see is the first time you run the program you'd have to set up the LFO but not get its value, you'd use the delay pot instead. I guess you'd also have to make it so that if you adjust the delay time pot (different POT pin) that it would override the tempo control.

Am I dreaming, or would this work? You'd need some debounce logic at the switch itself to keep it from screwing up your delay rate, but that's easy enough. You could even do low-pass filtering on it in the software (like the POTFIL routine.)

Matt Farrow

Actually, that seems like a very effective solution. The POT inputs are DC so a switch is just as valid as a pot and the POT input should go to a true 0 when shorted to ground.

Has anyone got this to work?

Any chance to see something like a tap tempo working around here?

Have a look here, tap tempo using pretty much the method discussed above.

http://www.spinsemi.com/forum/viewtopic.php?t=302