Software PWM is necessary when you cannot use hardware PWM. PWM is used for example to control and pilot servo motors.
You can then create a software PWM like this:
// Creates a Software Pwm channel on GPIO pin 17 with a frequency of 200 hertz an initial duty cycle of 0%
var softwarePwmChannel = new SoftwarePwmChannel(17, 200, 0);By default SoftwarePwmChannel is using a low priority clock to emulate the PWM. It is ok if you have leds and other non time sensitive elements attached.
Important: if you have clock sensitive elements attached to this software PWM, you need to use a high precision timer. In order to make it happen, you need to select it at creation time by passing true to the usePrecisionTimer parameter in the constructor:
var softwarePwmChannelWithPrecisionTimer = new SoftwarePwmChannel(17, frequency: 50, dutyCyclePercentage = 0.5, usePrecisionTimer: true);Usage is the same as the PwmChannel.
This example shows how to start the PWM, previously open on GPIO 17. It will start a 50Hz software PWM with 50% duty cycle:
softwarePwmChannel.Start();Usage is the same as the PwmChannel.
This example shows how to change the duty cycle of the PWM, previously open on GPIO 17. Duty cycle is changed for 25% with immediate effect if the PWM is already started.
softwarePwmChannel.DutyCycle = 0.25;Usage is the same as the PwmChannel.
This example will stop the PWM previously open on GPIO 17.
softwarePwmChannel.Stop();The high precision software PWM is resource intensive and is using a high priority thread. You may have resources issues if you are using multiple high precision software PWM. Always prefer hardware PWM to software PWM when you can have access.