Hands-On Robotics Programming with C++

How PWM works

In the previous Blink.cpp program, we applied a digital signal from the RPi to the LED. Digital signals either have a HIGH state or a LOW state. In, HIGH, state the Raspberry Pi pins produces a voltage of 3.3V and in a LOW state, the pins produce a voltage of 0V. Consequently, at 3.3V, the LED is on with full brightness and at 0V, the LED is turned off:

To reduce the brightness of the LED, we need to reduce the voltage. To reduce the voltage, we use PWM. In PWM, a single wave with one full repetition is called a cycle and the time taken for a cycle to complete itself is called a period. In the following diagram, the red lines ...