SIMPLE TAP TEMPO LFO

[3080]

[theehman]

Where's the output?

[CynicalMan]

Where's the output?

The LED controls an LDR.

What's the code for the PIC?

[theehman]

Where's the output?

The LED controls an LDR.

What's the code for the PIC?

D'oh!!!

[3080]

Where's the output?

The LED controls an LDR.

What's the code for the PIC?

here:
PIC12F683 Tap Tempo LFO (v.B)
http://www.strangedesigncs.heliohost.org/electronics.html#

[3080]

As audio-path I used the Tremulus Lune, with 25k trim.

[Transmogrifox]

I love those 12F683 chips.  With some minor code modifications you could probably use the internal 4Mhz RC oscillator & get acceptable results.  It would eliminate a few external components.

[JKowalski]

I love those 12F683 chips.  With some minor code modifications you could probably use the internal 4Mhz RC oscillator & get acceptable results.  It would eliminate a few external components.

Sadly, no. The 20mHz oscillator is necessary to get a good PWM resolution (10 bits) at an acceptably high frequency (19.5kHz) which is just at the edge of the audio band and not too much trouble to get rid of. Bringing the clock frequency down to 4mHz would force you to choose either bad resolution or a annoyingly low PWM frequency with the chance of bleed into the audio circuit.

Oh, it would be nice to get those pins free though 

[Transmogrifox]

Doh!  I knew I was missing something obvious   Thanks for pointing that out.

I should know better because I once bounced around the idea of trying to make a simple 12-bit DSP effect with one of these & shelved the idea when I realized I couldn't do 12-bit PWM at an acceptable frequency ... Not to mention the extra processing time needed for each operation to do 12-bit processing in an 8-bit processor.  I figured the end result would not be worth the time invested

But maybe a simple delay effect with 8-bit resolution using a compander to keep the full resolution...perhaps that would be worth trying.