Using hardware capture

[isaac]

Hi Bruce
i am trying to use your code on 18f452 but it seems to stop at start i must be missing something

DEFINE LOADER_USED 1 ' uses a bootloader
Include "Modedefs.Bas"

Define OSC 20
clear

' Setup Hardware for uart
DEFINE HSER_BAUD 9600
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_CLROERR 1
Symbol Capture = PIR1.2 ' CCP1 capture flag
T1 VAR WORD ' 1st capture value
PW VAR WORD ' 2nd capture value & ultimately final pulse width
TRISC.2 = 1 ' CCP1 input pin (Capture input)
INTCON.7 = 0 ' Interrupts off

hserout [" Start Measure ",10,13 ]
ReLoad:
CCP1CON = 000101 ' Capture mode, capture on rising edge
T1CON = 0 ' TMR1 prescale=1, clock=Fosc/4, TMR1=off (200nS per count @20MHz)
TMR1H = 0 ' Clear high byte of TMR1 counter
TMR1L = 0 ' Clear low byte
T1CON.0 = 1 ' Turn TMR1 on here
Capture = 0 ' Clear capture int flag bit
While !Capture ' Wait here until capture on rising edge
Wend

' Rising edge detected / stuff Timer1 value in T1
T1.HighByte = CCPR1H
T1.LowByte = CCPR1L

CCP1CON.0 = 0 ' Configure capture for falling edge now
Capture = 0 ' Clear capture interrupt flag bit

While !Capture ' While here until capture on falling edge
Wend

' Falling edge detected / stuff Timer1 value in PW
PW.HighByte = CCPR1H
PW.LowByte = CCPR1L

PW = PW-T1 ' High pulse width = PW-T1
' Convert to uS for 20MHz osc with 200nS Timer1 ticks
PW = (PW * 2)/10
hserout ["uS High = ",dec PW,10,13 ]
'DEBUG dec PW,"uS High",13,10 ' Output to RS232 display
GOTO ReLoad

END

[Bruce]

Not sure what you mean by it seems to stop at start but timer1 is running a lot faster at 20MHz, and you don't mention how far it gets or what it shows as the result, so it's tough to help.

Have you tried at 4MHz?

[isaac]

Sorry Bruce
But got it going now
i meant it always displayed: start Measure on pc and no measurements but its ok now
thanks for you support

Isaac