Re: Measuring motor RPM with micro.
- From: Rich Grise <richgrise@xxxxxxxxxxx>
- Date: Wed, 14 Jun 2006 15:59:14 GMT
On Wed, 14 Jun 2006 05:46:31 -0700, seegoon99 wrote:
Hi all.
I am trying to measure the RPM of a motor and have a few questions.
The motor is turning slowly(about 132RPM after gearing). There is an
"optical encoder"
on the shaft that gives me 8 pulses / rev.This gives me a pulse every
56ms or so.
How can I calculate the RPM of the motor WITHOUT using floating point
routines and in
a fairly fast time.
I could wait 1 second , count the number of pulses / 8 * 60 to get RPM
, but this takes far to long(1s) :0( I can measure fewer pulses , but
the time is still to long.
I could measure the period of 1 pulse , invert / 8 * 60 to give RPM.
This is much quicker , but involves floating point routines. I can gate
a timer in the micro with the pulses from the encoder to give me a
count in the micro , but this will also involve floating point routines
to get back to rpm.
Is there a simple solution to this problem(probably) and I've missed
the boat completely or am I stuck with the options I have described:0(
Cheers
Rob
I saw a guy do this in hardware with two or three banks of counters.
He used the first to count, say, milliseconds in one period, then
took that result and preloaded another counter which divided some
fixed clock by it, giving 1/t * some factor, which he then displayed,
or counted again, I don't remember exactly. but it _can_ be done. :-)
Good Luck!
Rich
.
- References:
- Measuring motor RPM with micro.
- From: seegoon99
- Measuring motor RPM with micro.
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