PT2399 Tap Tempo using uC and clock feedback

[CooperL]

Has anyone ever tried something like this?

I'm imagining using a JFET as a variable resistor to set the delay time on a PT2399.  The gate voltage on the JFET would be set by a PWM generated by a microcontroller (PIC, ATTiny...) that would take as input a tapped tempo. 
HERE's THE CATCH
You could feed the clock signal back from PT2399 (pin 5 I think?) to the micro to stabilize and linearize the tempo control.  You'd end up with a closed loop control system which would make it much easier to control the JFET. 
Of course, you'd have to figure out how many clock pulses from the PT2399 correspond to one delay, but I don't think that would be very difficult.

Any thoughts?  Has anyone ever tried this before?  Is this overkill/not necessary?

[slacker]

It's been discussed before, in principle it's a good way to do tap tempo for a PT2399. I don't know that anyone has actually tried it.
You can get the clock frequency to delay time relationship from the data sheet. You will probably need to divide the clock frequency down so that you can count it on the ucontroller.

[CooperL]

It's been discussed before, in principle it's a good way to do tap tempo for a PT2399. I don't know that anyone has actually tried it.
You can get the clock frequency to delay time relationship from the data sheet. You will probably need to divide the clock frequency down so that you can count it on the ucontroller.

Yeah, I was thinking I'd probably have to do some clock division to get a usable frequency.  Maybe use a counter or flip flops and divide by 32?

[Andre]

You might want to check this thread