Pulse Width Modulation Signal Generation with MCUs
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Pulse Width Modulation (PWM) is a technique that modulates a digital signal to produce an analog effect. It generates a square wave with varying duty cycle, which is the ratio of the high pulse duration to the total period. PWM can be used to transfer analog values over digital lines, modulate intensity of lights and power systems like DC motors. While microcontrollers have hardware for PWM generation, it can also be done in software by setting a timer to produce pulses with frequencies and durations defined by the desired duty cycle.
Pulse Width Modulation Signal Generation with MCUs
- 1. Pulse Width Modulation Signal Generation with MCUs Corrado Santoro ARSLAB - Autonomous and Robotic Systems Laboratory Dipartimento di Matematica e Informatica - Universit`a di Catania, Italy santoro@dmi.unict.it L.A.P. 1 Course Corrado Santoro Using PWM
- 2. Pulse Width Modulation Pulse Width Modulation (PWM) is a technique of modulation of a digital signal in order to obtain an analog value. It based on generating a square wave with a given frequency In the square wave, the “0” part and the “1” part have different duration The difference, in percentage, is called duty cycle Corrado Santoro Using PWM
- 3. Duty Cycle: Definition The Duty Cycle is defined as the percentage of Ton with respect to the total period Ppwm of the signal: Duty Cycle = Ton Ppwm · 100 Corrado Santoro Using PWM
- 4. Usage of Pulse Width Modulation PWM has multiple utilisations: 1 To simply transfer an analog value over a digital line; devices receiving a PWM signal can interpret the “analog value” by measuring the duration of the “1” part with respect to the total frequency; 2 To modulate a typical on/off system; e.g. to change the intensity of a light generated by a lamp, a LED, etc.; 3 To drive power systems without affecting performances; e.g. to drive a DC motor. Corrado Santoro Using PWM
- 5. Generation of a PWM signal Microcontrollers often have peripheral able to generate a PWM signal in hardware, however... ... to generate a PWM signal is not harder than flashing a LED. The differences are: Frequency is higher; On and Off times are different; The timer has to be set-up by taking into account the resolution we need. Corrado Santoro Using PWM
- 6. Pulse Width Modulation Signal Generation with MCUs Corrado Santoro ARSLAB - Autonomous and Robotic Systems Laboratory Dipartimento di Matematica e Informatica - Universit`a di Catania, Italy santoro@dmi.unict.it L.A.P. 1 Course Corrado Santoro Using PWM