Component: PWM (Internal) (General Output)

Author	Matrix Ltd
Version	2.1
Category	General Output

PWM (Internal) component

Pulse Width Modulation, a versitile way of generating a digital pulse using mark / space modulation. Uses the capture compare peripherals onboard most Microcontrollers to generate accurate waveforms without any intervention from the processor. Useful for generating audio, controlling the speed of motors, brightness of LED etc.

Component Pack

BASICIO

Detailed description

No detailed description exists yet for this component

Examples

Here is a basic example to control the PWM duty based on an ADC reading.

PWMDemo

Digital PWM trace

File:PWMDigital.jpg

Here is another basic example which ramps the PWM duty cycle up and down. If the PWM output pin is connected to a LED and series resistor then the LED will smoothly transition between on bright and off.

PWM Fader

Downloadable macro reference

	ChangePeriod
Sets the overall period and prescaler of the output PWM signal.
- UINT	Period
The maximum number that will represent 100% on, PIC/AVR: 0-255 16-bit PIC: 0-65535
- INT	Prescaler
The scaler used to divide the system clock speed down to the PWM rate.
- VOID	Return

	Disable
Disables a PWM channel and allows the default output / input state to be resumed
- VOID	Return

	SetDutyCycle
Sets the PWM duty cycle in terms of on/off based on the current period setting. E.g. if period = 255 then duty of 128 is equal to 50% on and 50% off. 16-bit PIC users should use the 10bit duty function to access the full range.
- BYTE	Duty
8-bit PWM duty 0-255
- VOID	Return

	Enable
Enables a PWM channel as an output overriding the default output pin state.
- VOID	Return

	SetFrequency
Sets a PWM of the specifed frequency at a duty of 50% Ideal use is a frequency generator
- ULONG	Frequency
Enter frequency in Hz
- VOID	Return

	SetDutyCycle10Bit
PIC/AVR - Sets the full scale PWM duty cycle based on the current period setting. If period = 255 then Duty of 512 is equal to 50%. 16-bit PICs have a 16-bit period range available. If period = 65535 then Duty of 32768 is equal to 50%.
- UINT	Duty
PWM duty PIC/AVR: 0-1023 16-bit PIC: 0-65535
- VOID	Return

Property reference

	Properties
	PWM Timer
Timer associated with PWM to drive the output. Warning - All PWM channels linked to the same timer will share the same period and prescaler settings.
	Period Overflow
Allows the user to change the number of counts for the whole PWM period. Note that all PWM channels based on the same timer will share the same period overflow. PIC/AVR Range: 0 - 255 16-bit PIC Range: 0 - 65535
	Prescaler
Allows the user to change the number of program cycles per PWM cycle count. Note that all PWM channels based on the same timer will share the same prescaler.
	Period (us)
Displays the length of time to complete one PWM cycle.
	Frequency (Hz)
	Frequency (KHz)
Displays the frequency of PWM cycles per second.
	Required Frequency (Hz)
Type in your required frequency in Hz and the component will automatically calculate the best prescaler and period to acheive the frequency with the maximum possible resolution.
	Calculated Frequency (Hz)
The frequency we have ended up acheiving using the calculated period and prescaler
	Calculated Period
The suggested period setting to use to acheive the calculated frequency.
	Calculated Prescaler
The suggested prescaler setting to use to acheive the calculated frequency.
	Apply To Defaults
Applies the calculated period and prescaler settings to the PWM component default settings.
	Connections
	Channel
Selects which PWM channel the component is connected to.
	Alternative pin
Allows an alternate pin to be used if available. Note that on some devices you will also have to change this setting in the device configuration.
	PWM Pin
Specifies the pin assigned to the PWM channel selected
	Remap Pin
Allows the PWM hardware pin to be reassigned to another pin
	Simulations
	Representation
Edits how the PWM is shown on the simulation panel.