Triggering 5 TTL clocks simultaneously


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  1. #1
    TurboLS's Avatar
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    So you're saying something like:

    IF PWM output is high, start the horizontal clocks

    Yeah, using another I/O pin is not a problem, cuz at this point i think i am using 2 pins of portA

    How would I go about getting the HPWM to oscillate at 3.6kHz with a 25% duty cycle? I will look at the manual again later today or tomorrow probably and see if i can figure it out.

    thanks again, you are a huge help.

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    it's a bit more than if pin is high... IF the according pin is at the rising edge of the signal... this ensure the right timing. Use interrupt source INT0, INT1 or else you can have on the rising edge... will be really easy now. The only thing you have to care about is the timing and latency in the other routines to get interrupt as quick as possible.

    For the HPWM frequency and duty cycle, try

    HPWM 1,64,3600 ' supposed to send HPWM 3.6KHZ at 25% duty

    i don't know how accurate it will be. In my purpose i always set all the register myself. In your datasheet they tell you how to calculate everything.
    Last edited by mister_e; - 22nd February 2005 at 19:29.
    Steve

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    There's no problem, only learning opportunities.

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    What pin would that HPWM be coming off of??

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    HPWM channel = CCP1 of your 18F4520 = PIN RC2 PIN 17
    Steve

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    There's no problem, only learning opportunities.

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    So I guess I could have it running in the background, then when I want to start the horizontal clocks, I could do an ON INTERRUPT command to make sure it is on the rising edge of the Reset HWPM clock.

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    you don't have to make sure it's on the rising edge. Interrupt will do it for you. When you set your interrupt you can select rising or falling edge.
    Steve

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    There's no problem, only learning opportunities.

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    And I set that in the registers, right? And then I can run a wire from PIN 17 to an interrupt pin and do an ON INTERRUPT command? Would it look something like this or totally different? I am going to try and find some examples.

    horizloop:
    ON INTERRUPT
    PORTB.2 = 0
    PORTB.3 = 1
    PAUSEUS 139
    PORTB.3 = 0
    PORTB.2 = 1
    PAUSEUS 50
    ADCIN 0, adval ' A/D 8 bit value from PORTA.0 into adval
    SEROUT2 PORTC.6,16416,[BIN8 adval,13,10] ' Output 8 bit word serially to PC from C.6
    PAUSE 87
    horizpulse = horizpulse + 1
    IF horizpulse < 784

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