Motor RMP

[jjude]

Sorry my bad english!
I need code this project.
I need measure motor "speed/minute", is this RMP english
(finish this in RMP)?
Anyway. How i can measure and count RMP when
sensor "send" one pulse/round (signal is "0" and pulse is "1").
PIC16F877A

[Ttelmah]

RPM (revs per minute).
Answer will depend on what sort of rev 'range' is involved, what sort of accuracy you need, and what sort of 'update rate'.
Normally, given the low speeds involved for most motors, you will get better results by measuring the time interval between successive pulses, rather than trying to count pulses. This gives you effectively the reciprocal of the required value, and allows a measure to be made much faster.
Have a look at:
<http://www.ccsinfo.com/forum/viewtopic.php?t=2507&highlight=tachometer>

Which has some pointers to such systems.

Best Wishes

[jjude]

RPM (revs per minute) that is it!
-Range about 200-3000rmp (boat motor)
-20-50rmp step is ok
-Updaterate about 2-3sec

[jjude]

Is this goode idea and working 16f877a?

http://www.vermontficks.org/dtachc.htm