With an 8MHz clock on a PIC16, the closest you can get is 125kHz (PR2=7) or 111kHz (PR2=8). Also, the resolution will be less than 4 bits (0-8 or just a little more than 3 bit resolution).
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With an 8MHz clock on a PIC16, the closest you can get is 125kHz (PR2=7) or 111kHz (PR2=8). Also, the resolution will be less than 4 bits (0-8 or just a little more than 3 bit resolution).
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With a nonstandard 9.6Mhz crystal, you can get right on 120Khz.Originally Posted by rmteo
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i've come out with manually pwm generator coding.this is my code:
DEFINE OSC 8
TRISC.2=0
PWM_STATUS VAR PORTC.2
MAIN:
HIGH PWM_STATUS
PAUSEUS 4
LOW PWM_STATUS
PAUSEUS 4
GOTO MAIN
END
total time per cycle=4u+4u=8us...so...f=125khz...i hope this will work.i will tested it today...
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Except that it'll take at least one cycle to set the pin high (probably 2), one cycle to set the pin low (probably 2), 2 cycles to execute the GOTO MAIN...
And if you'd read your PBP manual, you'd notice that pauseus has a minimum delay of 12us vs. the 4us you want.
Therefore, you're code will probably output a 50% duty cycle square wave at about 66.6Khz...give or take...
And do you want actual PWM or just a 120Khz pulse? 2 totally different things you know...
Last edited by skimask; - 11th September 2008 at 00:33.
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just 120khz pulse only one time use.actually,i want to inject the pulse when the zero-crossing interrupt occur to couple with the 50hz ac power line.the zero-crossing interrupt has be discuss before in this forum.
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Looks like you're well on your way over here http://forum.microchip.com/tm.aspx?m=364475
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oh no.my x-10 receiver circuit cannot detect 100khz-120khz pwm frequency.i've tested today and you know what, it need a 1Mhz pwm frequency.how can i generate it.oh nooo.
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