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modified on 17 September 2014 at 19:32 ••• 22,068 views

05-03 PWMFrequency

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This example program uses an analog input to control the period of a PWM.

The signals used for this example are listed below:

Signals Used and Connector Locations for Example 05-03
Signal LPC4330 PIN NAME BAM210E BAM210 BAM200E BAM200 Used for
A0 P7_4 J8-1 J8-1 S4-3 S4-3 Potentiometer
PWM1 P1_7 J9-3 J9-3 S2-3 S2-3

The following schematic can be used to build the circuit with a BAM210E or BAM210.

BAM210
Schematic for example 05-03
/*Program Example 5.3: Uses analog input to control PWM period
                                                                     */
#include "mbed.h"
PwmOut pwm(PWM1);
AnalogIn Ain(A0);

int main() {
    while(1){
      pwm.period(Ain/10+0.001);            // set PWM period
      pwm=0.5;                             // set duty cycle
      wait(0.5);
    }
}

PWM1 was captured on the oscilloscope in the image below.

The following image shows the built circuit on a BAM210E.