read a pwm

[fred.pacc]

hello,
I need to increase a frequency of 120Hz to 10kHz PWM so
I have a measure of a pwm dutycyle has 120hz and take its value to send in another PWM at 10kHz with a pic 18F2420

can you give me a procedure?

thank you

[Ioannis]

I can give you an idea to start. Use the Pulsin command to measure the width of High and Low pulses. Or use timer.Start an stop the timers on each edge of the 120Hz pulse and then find the frequency or period.

Ioannis

[Acetronics2]

Hello

I think Darrel already has published something ( of course nice !!! ) about that ...

Alain

Here it is ...

'****************************************************************
'*  Name    : FREQx2.bas                                        *
'*  Author  : Darrel Taylor                                     *
'*  Date    : 3/2/2007                                          *
'*  Version : 3.0                                               *
'*  Notes   : Doubles the frequency of input pulses,            *
'*          : and maintains the same DutyCycle as the Input.    *
'*          : Range = .1hz to 500 hz  (0-40% max DutyCyle)      *
'*          : Target = PIC12F629/675                            *
'****************************************************************
@  __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
DEFINE  NO_CLRWDT 1
Clear
SpeedPin   VAR GPIO.2                       ; Input from speed sensor
SpeedX2Pin VAR GPIO.4                       ; Output to Speedometer
IdleState  VAR GPIO.0                       ; State of input when sensor
                                            ;    is not on a "Slot"
Invert     VAR GPIO.1                       ; Inverts output if = 1
OPTION_REG.7 = 0                            ; enable weak Pull-ups
WPU = 3                                     ; weak Pull-up on GP0 and GP1      
;_____________________________________________________________________________
LastState  VAR BIT                          ; Last state the Input changed to
LoopCount  VAR byte                         ; Counts the loops of each pulse
LoopCount1 VAR byte
LoopCount2 VAR byte
PulseWidth  VAR byte  BANK0                 ; Counts the loops of output pulse
PulseWidth1 VAR byte  BANK0
PulseWidth2 VAR byte  BANK0
LastPulseWidth  VAR byte                    ; saved width of last pulse
LastPulseWidth1 VAR byte                    ;    so it can duplicate it
LastPulseWidth2 VAR byte
CycleWidth  VAR byte  BANK0                 ; Counts the loops of output cycle
CycleWidth1 VAR byte  BANK0
CycleWidth2 VAR byte  BANK0
OutPulseCount VAR BIT
 
CMCON = 7
'ANSEL = 0    ; for 12F675
SpeedX2Pin = IdleState
OUTPUT SpeedX2Pin
Main:
    LoopCount = LoopCount + 1               ; 24-bit counter
    If LoopCount = 0 Then
        LoopCount1 = LoopCount1 + 1         
        if LoopCount1 = 0 then
            LoopCount2 = LoopCount2 + 1
        endif
    endif
    IF SpeedPin <> LastState then           ; If Input State Changed?
        LastState = SpeedPin
 
        if LastState = (IdleState ^ 1) then         ; Start of Input Pulse
            CycleWidth  = LoopCount
            CycleWidth1 = LoopCount1
            CycleWidth2 = LoopCount2
            ASM
                bcf   STATUS,C              ; CycleWidth = LoopCount / 2
                rrf   _CycleWidth2, F       ; Output Cycle is half of Input
                rrf   _CycleWidth1, F
                rrf   _CycleWidth, F
            ENDASM
            LoopCount  = 0                  ; reset LoopCount
            LoopCount1 = 0
            LoopCount2 = 0
        else                                ; End of Input Pulse
            PulseWidth  = LoopCount
            PulseWidth1 = LoopCount1
            PulseWidth2 = LoopCount2
            ASM
                bcf   STATUS,C              ; PulseWidth = PulseWidth / 2
                rrf   _PulseWidth2, F       ; Output Pulse is half of Input
                rrf   _PulseWidth1, F
                rrf   _PulseWidth, F
            ENDASM
            LastPulseWidth = PulseWidth
            LastPulseWidth1 = PulseWidth1
            LastPulseWidth2 = PulseWidth2
            SpeedX2Pin = ((IdleState ^ 1) ^ Invert) ; start First Output Pulse
            OutPulseCount = 0
        endif
    else
        if SpeedX2Pin = ((IdleState ^ 1) ^ Invert) then
            if PulseWidth = 0 then          ; countdown output time (24bit)
                if PulseWidth1 = 0 then
                    if PulseWidth2 = 0 then
                        SpeedX2Pin = (IdleState ^ Invert) ; end of pulse, 
                    else                       ; wait for next transition
                        PulseWidth2 = PulseWidth2 - 1
                        PulseWidth1 = 255
                        PulseWidth  = 255
                    endif
                else
                    PulseWidth1 = PulseWidth1 - 1
                    PulseWidth  = 255
                endif
            else
                PulseWidth = PulseWidth - 1
            endif
        else
          @ NOP                             ; Keep the loop symmetrical
          @ NOP
          @ NOP
          @ NOP
          @ NOP
          @ NOP
        endif
 
        if OutPulseCount = 0 then
            if CycleWidth = 0 then          ; countdown to Midpoint of cycle
                if CycleWidth1 = 0 then
                    if CycleWidth2 = 0 then
                        SpeedX2Pin = ((IdleState ^ 1) ^ Invert) ; Start second pulse
                        OutPulseCount = 1
                        PulseWidth  = LastPulseWidth
                        PulseWidth1 = LastPulseWidth1
                        PulseWidth2 = LastPulseWidth2
                    else
                        CycleWidth2 = CycleWidth2 - 1
                        CycleWidth1 = 255
                        CycleWidth  = 255
                    endif
                else
                    CycleWidth1 = CycleWidth1 - 1
                    CycleWidth  = 255
                endif
            else
                CycleWidth = CycleWidth - 1
            endif
        else
          @ NOP                             ; Keep the loop symmetrical
          @ NOP
          @ NOP
          @ NOP
          @ NOP
        endif
    endif
goto Main
end

...

Just for the idea ... !