after finally getting progress made on this with good results its nice to see that we can alter the available features if they need to be tweeked to our needs, not something ive done before and a new concept that will get used more at some point im sure.
as the whole pulsin was the key issue for moving some of my code over it can at least now allow me to move forward and get started on that some point soon.
thankyou for the examples they are a great reference and help.
tony
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Another (and probably better) method to detect the duration of a pulse is to use Timer1. A High signal starts the timer and a Low signal stops the timer. With an 8MHz clock and a timer Prescaler value of 2, each timer tick is 1 microsecond.
I did this using a PIC18F690 but should work fine on any PIC with Timer 1. I think this is better than counting instruction cycles like the first example. This should be as accurate as the clock source with an uncertainty of about 1 - 2us. The Macro will measure pulses from about 8us to 65,535 microseconds with good accuracy. With an input signal of 1ms it consistently reads between 999 and 1000us. Note that I used a macro instead of a sub.
; Measure Positive Pulse Width Test Code
; Using Timer 1
#chip 16F690,8
;USART settings
#define USART_BAUD_RATE 9600
#define USART_BL0CKING
DIR PORTB.7 OUT
;Input Pin and Direction
#define InPin PORTC.6
Dir InPin In
Dim Time_us As WORD
;Init timer and clear value to zero
InitTimer1 Osc, PS1_2
ClearTimer 1
; Main Program starts here
Do
Pulse_In (InPin, time_us)
HserPrint time_us
HserPrintCRLF
Loop
macro Pulse_In (Pin, Variable)
;Make sure the pin is not already high
Wait Until Pin = OFF
;Start timer on signal high
Wait Until Pin = ON
StartTimer 1
;Stop timer on signal low
Wait Until Pin = Off
StopTimer 1
variable = Timer1
ClearTimer 1
end macro
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thanks bill and kent.
after finally getting progress made on this with good results its nice to see that we can alter the available features if they need to be tweeked to our needs, not something ive done before and a new concept that will get used more at some point im sure.
as the whole pulsin was the key issue for moving some of my code over it can at least now allow me to move forward and get started on that some point soon.
thankyou for the examples they are a great reference and help.
tony
Another (and probably better) method to detect the duration of a pulse is to use Timer1. A High signal starts the timer and a Low signal stops the timer. With an 8MHz clock and a timer Prescaler value of 2, each timer tick is 1 microsecond.
I did this using a PIC18F690 but should work fine on any PIC with Timer 1. I think this is better than counting instruction cycles like the first example. This should be as accurate as the clock source with an uncertainty of about 1 - 2us. The Macro will measure pulses from about 8us to 65,535 microseconds with good accuracy. With an input signal of 1ms it consistently reads between 999 and 1000us. Note that I used a macro instead of a sub.
; Measure Positive Pulse Width Test Code ; Using Timer 1 #chip 16F690,8 ;USART settings #define USART_BAUD_RATE 9600 #define USART_BL0CKING DIR PORTB.7 OUT ;Input Pin and Direction #define InPin PORTC.6 Dir InPin In Dim Time_us As WORD ;Init timer and clear value to zero InitTimer1 Osc, PS1_2 ClearTimer 1 ; Main Program starts here Do Pulse_In (InPin, time_us) HserPrint time_us HserPrintCRLF Loop macro Pulse_In (Pin, Variable) ;Make sure the pin is not already high Wait Until Pin = OFF ;Start timer on signal high Wait Until Pin = ON StartTimer 1 ;Stop timer on signal low Wait Until Pin = Off StopTimer 1 variable = Timer1 ClearTimer 1 end macro