[sdiy] Tap Tempo LFO
elliot at speakeasy.net
Thu Dec 10 08:03:52 CET 2009
On Wed, 09 Dec 2009 11:19:11 -0700
Eric Brombaugh <ebrombaugh1 at cox.net> wrote:
> General consensus seems to be that delays in the 1ms - 20ms will be
> needed, so by my estimation this means we'll need a clock signal with a
> maximum frequency of 4Mhz or so. To avoid noticeably discrete steps we
> should probably have resolution of at least 100 steps at the top of the
> range, so figure about 40kHz, or a delay increment of 10us in a 4k BBD.
Try the AVR Tiny45. Its timer1 is a "fast peripheral clock" that's on an 8x PLL with the CPU clock. With the chip's internal oscillator at 8MHz, it will do 64MHz.
1/64MHz * 4k BBD = 64uS resolution. Not the 10uS resolution you want, but good enough for rock and roll? And 1/64MHz * 4k * 256 = 16mS before you even mess with prescaling.
(I've been thinking about doing this for a while, just never gotten to it.)
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