Post by thread:Timing Pulses

Hi, i need some help, i am trying to time a PWM signal whose length varies from 0.2-2mili seconds, i am using a loop at the moment that increments a counter until the pulse drops back to 0. The problem is that it does not seem to work very well. I need to get about 8 bits resolution. I will email the code if that helps. Thanks in advance. PS I am using a PIC16C84 running with a 4MHz crystal. -- +-------------------------------------------------------------------+ | Martin Bowman - University of Warwick, Coventry, UK | | - 3rd Year Electronic Engineering | | - E Mail (spam_OUTesukqTakeThisOuTwarwick.ac.uk) | | - Packet .....G7VHEKILLspam@spam@GB7COV.GBR.EU | +------------------ IF IT AINT BROKE - DONT FIX IT -----------------+

; Let me give it a shot ; 2000 usec - 200 usec = 1800 usec ; 1800 usec/256 = 7 used bsf Aport,0 ;start the PWM output movlw 65 ;set up delay for minimum width movwf Loop_Counter Loop1 decfsz Loop_Counter goto Loop1 Loop2 movf Pulse_Width,w ;Get the desired pulse width subwf Loop_Counter ;Compare to the current loop count skpnc ;if current count is >= desired count bcf Aport,0 ;then terminate the pulse incfsz Loop_Counter ;count up the loop until it rolls over goto Loop ;back around to beginning of loop ______________________________ Reply Separator _________________________________ Subject: Timing Pulses Author: esukqKILLspamCSV.WARWICK.AC.UK at internet Date: 11/5/96 3:00 PM Hi, i need some help, i am trying to time a PWM signal whose length varies from 0.2-2mili seconds, i am using a loop at the moment that increments a counter until the pulse drops back to 0. The problem is that it does not seem to work very well. I need to get about 8 bits resolution. I will email the code if that helps. Thanks in advance. PS I am using a PIC16C84 running with a 4MHz crystal. -- +-------------------------------------------------------------------+ | Martin Bowman - University of Warwick, Coventry, UK | | - 3rd Year Electronic Engineering | | - E Mail (.....esukqKILLspam.....warwick.ac.uk) | | - Packet EraseMEG7VHEspam_OUTTakeThisOuTGB7COV.GBR.EU | +------------------ IF IT AINT BROKE - DONT FIX IT -----------------+

Mr M R Bowman wrote: > > Hi, i need some help, i am trying to time a PWM signal whose > length varies from 0.2-2mili seconds, i am using a loop at > the moment that increments a counter until the pulse drops > back to 0. The problem is that it does not seem to work > very well. I need to get about 8 bits resolution. > > I will email the code if that helps. > > Thanks in advance. > > PS I am using a PIC16C84 running with a 4MHz crystal. Hi, I have been working on a system that counts pulses and pulse width using the 84 .I use both the T0 clock and INT on portB0 to generate ints. If you set the ints up so that an int is generated on the rising edge of portb0 and increment a counter every time an int is generated you can count pulses. now if you also set the clock to generate an int at a set duty cycle you can count the number of pulses on the portb0 pin within a set time. all of this can be done in the background and due to the nature of the ints it is also VERY presise. I hope this is of some use Peter........

Hello again, thanks for all your help with the timing pulses thing, i have that sorted out. Cheers. -- +-------------------------------------------------------------------+ | Martin Bowman - University of Warwick, Coventry, UK | | - 3rd Year Electronic Engineering | | - E Mail (esukqspam_OUTwarwick.ac.uk) | | - Packet @spam@G7VHEKILLspamGB7COV.GBR.EU | +------------------ IF IT AINT BROKE - DONT FIX IT -----------------+