'
'  AN #138 - RPM meter and rotational speed sensor with AT90S2313
'
'http://www.mcselec.com/index.php?option=com_content&task=view&id=106&Itemid=57
'
'                     (c) 2005-2006 MCS Eletronics Modified by diymania for use with a reflex detector.
'
' Program : Main program
'
' Note : this program calculate with recompiled mcs.lib with Genus(0) !
'                          see AN for details

Config Timer1 = Pwm , Prescale = 64 , Compare A Pwm = Clear Down , Pwm = 10

Dim W As Word
Dim Pinhz As Word
Dim Temp As Single
Dim Rpm As Word

Pinhz = 19444.3                                             ' 3.68MHz crystal. ' Constant PulseIN value for 10Hz
Pwm1a = 0

Do

    Pulsein W , Pinb , 2 , 1

    Temp = Pinhz / W
    Temp = Temp * 10
    Rpm = Temp / 1                                          ' One pulse per revolution.
    Temp = Rpm * 60

    Temp = 258.38 * Log(temp)
    Temp = Temp - 1437.2

    Rpm = Temp
    Pwm1a = Rpm

Loop