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.