https://hades.mech.northwestern.edu//index.php?action=history&feed=atom&title=C_Example%3A_PWM_Motor_Control 2026-04-06T12:05:42Z Revision history for this page on the wiki MediaWiki 1.35.9 https://hades.mech.northwestern.edu//index.php?title=C_Example:_PWM_Motor_Control&diff=4968&oldid=prev 2007-06-25T20:53:09Z

<p></p> <p><b>New page</b></p><div>__TOC__<br /> ==Code==<br /> Program to run a motor at different speeds using pulse width<br /> modulation (PWM), controlled by a push button.<br /> <br /> First include header file with definitions for specific PIC.<br /> Set fuses. HS is type of external clock, low voltage protection<br /> (LVP) is off, and the watchdog timer (WDT) is off.<br /> External clock frequency of 20 MHz is specified.<br /> <br /> #include &lt;18F4520.h&gt;<br /> #fuses HS,NOWDT,NOPROTECT,NOLVP<br /> #use delay(clock=20000000)<br /> <br /> Define pin names to be used in the main program. See header file<br /> for currently defined pin names.<br /> <br /> #define BUTTON PIN_A4<br /> <br /> Begin main body of program.<br /> <br /> void main() {<br /> <br /> Setup the CCP1 pin (PIN_C2 on the 18F4520 chip) to be a PWM<br /> output. Also set the timer to be used for PWM.<br /> <br /> setup_ccp1(CCP_PWM);<br /> setup_timer_2(T2_DIV_BY_1, 255, 1);<br /> <br /> Setup an infinite loop, using a while statement.<br /> <br /> while( TRUE ) {<br /> <br /> Check whether button is pressed or not, and vary duty cycle<br /> of PWM accordingly. Note that duty cycle is defined from 0-255<br /> with 0 being 0% and 255 being 100% (8-bit number).<br /> <br /> if (input(BUTTON)){<br /> set_pwm1_duty(235);}<br /> else {<br /> set_pwm1_duty(135);}<br /> }<br /> }<br /> ==Associated Circuitry==</div>

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