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LDmicro Forum - Low frequency multiplication?

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Low frequency multiplication? (by Tom J.)

I'm working on a project to do a very simple adjustable square wave frequency scaler.

Scaling down is not hard, I can do that with count circular and I'm sure there's a dozen other ways.

Multiplication on the other hand has me stumped, so far the only thing I can think to do is vary PWM duty cycle but that's not exactly what I'd like to do.

Is there an easy way to take a certain number of input pulses, multiply them and output that number of pulses to an output pin that I'm missing or are we limited to PWM for such a thing?
Thu Mar 1 2018, 22:50:59
Frequency multiplication (by Ziggy)
Well... I reckon it depends on what you actually need to as opposed to what you wish to do.

So tell us a bit more about input versus output frequency
Tell us about the duty cycle of out put frequency
and what is it to achieve?
Thu Mar 1 2018, 23:09:05
(no subject) (by Tom J.)
I'd like to be able to put a square wave into an input, multiply the number of pulses and then cycle an output pin at that frequency.

What I'm working on is a doodle to adapt speedometers and tachometers to work with sources that have incorrect scaling for them.
Sat Mar 3 2018, 13:21:05
(no subject) (by Ziggy)
OK..


what is the range of input frequencies?

what is the range of output frequencies?

what is the range of scaling factors?
Wed Mar 14 2018, 19:29:04
(no subject) (by Tom J.)
Sorry, busy with other projects but my skill level has slightly elevated since March too so that's good...

The range really isn't high, input and output both would typically be under 150khz and different applications would require a different scaling factor, particularly where vehicle speed is involved due to the dramatic differences in Speedometers and pulses per mile from various ECM/sensor/buffer modules.

For the most part if I could count frequency and turn it into a variable that would be a huge help. I'd like to do Speedometer and Tachometer correction but another application I'd like to explore involves using that input frequency to modify PWM output for a variable effort steering rack I'm playing with and that's something that's currently on the bench.

In this particular application the PWM is: 100% = minimal effort 0% = maximum effort.
The input pulse is 4000 pulses per mile which should be 66Hz at 60MPH and 33Hz at 30MPH.

I've got a couple of ladders to count RPM that I found here on the forum so I'll see what I can make them do unless somebody has a really simple way to count input frequency and turn it into a variable.
Thu Jun 7 2018, 20:03:29
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