mruby-mruby/mrbgems/hw-adc

hw-adc - ADC peripheral interface for mruby

This gem provides the ADC class for reading analog input 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 ESP-IDF ADC oneshot driver
• ports/rp2040/ - RP2040 using Pico SDK ADC hardware

Build Configuration

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

Ruby API

ADC.new

adc = ADC.new(pin)

• pin - ADC-capable GPIO pin number (Integer)
• Raises ArgumentError if the pin is not valid for ADC

ADC#read / ADC#read_voltage

Read the analog value as voltage (Float).

voltage = adc.read           # => 1.65
voltage = adc.read_voltage   # same

ADC#read_raw

Read the raw ADC value (Integer, typically 0-4095 for 12-bit).

raw = adc.read_raw   # => 2048

ADC#input

Returns the ADC input channel number assigned during initialization.

HAL Interface

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

int      mrb_adc_init(uint8_t pin);
uint32_t mrb_adc_read_raw(uint8_t input);
float    mrb_adc_read_voltage(uint8_t input);

• mrb_adc_init returns the input channel number (>= 0) on success, negative on error
• input parameter for read functions is the value returned by mrb_adc_init

License

MIT