User Manual

pLed.ChangeDutyCycle(dc) # ChangeDutyCycle() function in pLED output

pulse width 0~100% according to the variable dc.

print " ++ Duty cycle: %s"%dc # print information

time.sleep(delay) # it will delay after changing the pulse width for

each time, this parameter can be modified to change the LED’s lighting and dimming

speed.

time.sleep(1)

# decrease duty cycle from 100 to 0

for dc in range(100, -1, -step): # the luminance of the LED decreases with each

cycle.

# Change duty cycle to dc

pLED.ChangeDutyCycle(dc) # same as the last for loop

print " -- Duty cycle: %s"%dc

time.sleep(delay)

Now you w ill see the gradual change of the LED luminance, between bright and dim.

Summary

Through this experiment, you should have mastered the principle of PWM and how to

program Raspberry Pi with PWM. You can try to apply this technology to DC motor speed

regulation later.

SunFounder