Re: Measuring motor RPM with micro.
- From: meow2222@xxxxxxxxx
- Date: 14 Jun 2006 12:32:34 -0700
seegoon99@xxxxxxxxx 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
Or for a different approach, let a pulse begin an exponential
discharge, and at the next pulse read the v of the discharge: pulse v =
rpm. A key question here is how accurate you need it, and not how
accurate at all times but how accurate where. To explain this, you
might for example need it accurate at one speed, but could tolerate
increaseing inaccuracy at speeds further afield..
NT
.
- References:
- Measuring motor RPM with micro.
- From: seegoon99
- Measuring motor RPM with micro.
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