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mruby_io_PWM_en.md

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PWM

  • A class that supports Pulse Width Modulation (PWM) functionality.

Constructor

PWM.new( pin, *params )

  • Generate a PWM object by specifying the physical pin indicated by "pin."
  • Typically, "pin" is specified as an integer, but alternative methods (e.g., "B1" in PIC) are also acceptable.
  • When specifying the parameter frequency, the output starts with a duty cycle of 50%.
  • If you want to start the output with a duty cycle other than 50%, specify the parameter duty simultaneously.

Optional Parameters

param type description
frequency Integer,Float Specifies the frequency.
freq (Same as above)
duty Integer,Float Specifies the duty cycle.

Example of use:

# Generate an object for PWM output on pin 1. Output is not started yet.
pwm1 = PWM.new( 1 )

# Generate an object for PWM output on pin 1 and start the output with a frequency of 440Hz and a duty cycle of 30%.
pwm1 = PWM.new( 1, frequency:440, duty:30 )

Device-specific

  • Additional parameters such as unit names may be required.

Instance Methods

frequency( freq )

  • Starts the output or changes the frequency by specifying the frequency.
  • freq is specified as an Integer or Float.
  • Specifying 0 stops the output.
  • Changing the frequency does not affect the duty cycle.

Example of use:

pwm1.frequency( 440 )   #  Output at 440Hz

Device-specific

  • The maximum and minimum frequencies and resolutions depend on the device.
  • When stopping the output, it is desirable to stop it at LowLevel.
  • Whether to stop at the middle of a cycle (become LowLevel) or after the output of that cycle is complete when stopping the output is device-specific.

period_us( micro_sec )

  • Starts the output or changes the period by specifying the time of one cycle in microseconds.
  • micro_sec is specified as an Integer.
  • Specifying 0 stops the output.
  • Changing the period does not affect the duty cycle.

Example of use:

pwm1.period_us( 2273 )   # 1/2273us = 440Hz

duty( percent )

  • Changes the duty cycle by specifying a percentage from 0 to 100.
  • percent is specified as an Integer or Float.

Example of use:

pwm1.duty( 50 )

pulse_width_us( micro_sec )

  • Specifies the time in microseconds for which the output stays ON in one cycle.
  • micro_sec is specified as an Integer.
  • If a time longer than one cycle is specified, it will be set to the maximum value that can be ON without an error.

Example of use:

pwm1.pulse_width_us( 1000 )