mruby-mruby/mrbgems/hw-pwm

hw-pwm - PWM peripheral interface for mruby

This gem provides the PWM class for Pulse Width Modulation output from mruby. It is designed for embedded platforms such as ESP32 and RP2040.

Architecture

Platform-specific HAL implementations are in ports/ directories:

• ports/esp32/ - ESP32 using LEDC peripheral
• ports/rp2040/ - RP2040 using Pico SDK PWM hardware

Build Configuration

MRuby::CrossBuild.new('esp32') do |conf|
  conf.ports :esp32
  conf.gem core: 'hw-pwm'
end

Ruby API

PWM.new

pwm = PWM.new(pin, frequency: 1000, duty: 50)

• pin - GPIO pin number (Integer)
• frequency: - frequency in Hz (default: 0, disabled)
• duty: - duty cycle in percent 0-100 (default: 50)

PWM#frequency(freq)

Set frequency in Hz. Returns the frequency. Setting 0 disables output.

pwm.frequency(1000)   # 1 kHz
pwm.frequency(0)      # disable

PWM#period_us(us)

Set period in microseconds. Returns the corresponding frequency.

pwm.period_us(1000)   # 1ms period = 1 kHz

PWM#duty(pct)

Set duty cycle in percent (0.0-100.0). Clamped to range.

pwm.duty(75.0)

PWM#pulse_width_us(us)

Set pulse width in microseconds. Duty cycle is calculated from current frequency.

pwm.pulse_width_us(500)   # 500us pulse width

HAL Interface

To add support for a new platform, create a ports/<name>/ directory and implement the following C functions declared in <mruby/pwm.h>:

void mrb_pwm_init(uint32_t pin);
void mrb_pwm_set_freq_duty(uint32_t pin, float frequency, float duty);
void mrb_pwm_set_enabled(uint32_t pin, bool enabled);

• frequency is in Hz, duty is in percent (0-100)
• mrb_pwm_set_enabled is called with false when frequency is 0

License

MIT