Timing Measurement

[Tobias]

HI
I am wanting to measure time between a switch closing and a programmed Pulsewidth. The code executes fine. When I push the button, the display reads out correctly. When I get the output of my pulse generator to the desired stop pulsewidth, an Elapsed time is displayed on the LED.

The elapsed time sees a bit off, yet I am not sure if its really a measurement problem or my perception. I don't have anyway of measuring it with an instrument at the moment.

Also is this the best route to take? I am trying to learn about TM0 and TM1 by looking through threads here. So I do have some TM config info in the code from playing around. Any links to TM0 info would be greatly appreciated. Or are there any books available that talk about Timers and CCP's that use PBP? It looks like I could use a CCP to get the pulsewidth too.


Thanks for the input
Toby

Include "modedefs.bas"	' Mode definitions for Serout
DEFINE OSC 20
 
OPTION_REG.7 = 0 'Pull Ups enabled
OPTION_REG.6 = 1 'PB0 interrupt on falling edge
OPTION_REG.5 = 0  'TMR0 Clock source CLK0
OPTION_REG.4 = 1  'TMR0 high to low
OPTION_REG.3 = 0  'Prescaler to timer0
OPTION_REG.2 = 0  'Timer prescaler 1:2
OPTION_REG.1 = 0
OPTION_REG.0 = 0

T1CON.5=0   'Prescaler 1:1
T1CON.4=0
T1CON.1=0   'Interal clock
T1CON.0=1   'Enable Timer
INTCON.4=0
ADCON1 = 6 'A2D Off

LCD            VAR    PortC.0
Start          var    PortB.0
Finish         var    PortB.1
DSRPM          Var    PortC.3
LDSRPM         var    word
HDSRPM         Var    Word
Time1          var    word
Time2          VAr    word
PB             var    PortB.2
Checker        var    byte
Seconds        var    byte
Remainder      var    word
RPM1000        var    byte
RPM100         var    byte
Display1000    var    byte
Display100     var    byte
Timer1000      var    byte
Timer100       var    byte 
TriggerRPM     var    word
  
Serout LCD, N9600, [$1b, $30]  
Serout LCD,N9600,["Ryan Timer",10,13,10,13]  

Pause 1000	' Wait .5 second

Repeat
    'Sets up backlighting
    iF pb = 0 tHEN 
       IF Checker = 0 then
          Serout LCD,N9600,[$1b ,$2a,123 ]
          Checker = Checker + 1
       else
       'pause 200
       if Checker = 1 then 
          Serout LCD,N9600,[$1b ,$2a,225 ]
          Checker = Checker + 1
       else
       'pause 200
       if Checker = 2 then 
          Serout LCD,N9600,[$1b ,$2a,0 ]
          Checker = 0
       endif
       endif
       endif
       pause 200
    endif
       
Serout LCD, N9600, [$1b, $30]
Serout LCD,N9600,[" Waiting",10,13]
TriggerRPM = 528
Until Start = 0 'B.0 goes low and starts timer
  
Serout LCD, N9600, [$1b, $30]
Serout LCD,N9600,[" Timer Activated",10,13]

INTCON.5=1 'Enable Timer0 Interrupt

on Interrupt goto Increment

'Measures RPM
Repeat
  Pulsin DSRPM, 0, LDSRPM
  PULSIN DSRPM, 1, HDSRPM
  HDSRPM = HDSRPM + LDSRPM
Until HDSRPM <= TriggerRPM

High Finish 'Turns on light

Serout LCD, N9600, [$1b, $30]
Serout LCD, N9600, ["E/T ", # Time2,".", # Time1/10,10,13]
End

disable
Increment:
Time1= Time1 +1
  If Time1 = 1000 then
     Time1 = 0
     Time2 = Time2 + 1
  endif
  INTCON.2 = 0
resume

[Tobias]

OK I got the TMR1 working. Pretty damn simple. It seems to me atleast, the most complicated part about getting any function of a PIC to work is finding the documentation. After that its a piece of cake.