This gem provides the GPIO class for controlling general-purpose input/output pins 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 GPIO driver
ports/rp2040/ - RP2040 using Pico SDK

The build system automatically compiles matching port sources based on conf.ports setting.

Build Configuration

# For ESP32
MRuby::CrossBuild.new('esp32') do |conf|
  conf.ports :esp32
  conf.gem core: 'hw-gpio'
end

# For RP2040
MRuby::CrossBuild.new('rp2040') do |conf|
  conf.ports :rp2040
  conf.gem core: 'hw-gpio'
end

Ruby API

Constants (direction/mode flags)

These flags can be combined with bitwise OR.

Flag	Value	Description
`GPIO::IN`	`0x01`	Input mode
`GPIO::OUT`	`0x02`	Output mode
`GPIO::HIGH_Z`	`0x04`	High-impedance (tri-state)
`GPIO::PULL_UP`	`0x08`	Enable pull-up resistor
`GPIO::PULL_DOWN`	`0x10`	Enable pull-down resistor
`GPIO::OPEN_DRAIN`	`0x20`	Enable open-drain output

GPIO.new

gpio = GPIO.new(pin, flags)

pin - GPIO pin number (Integer)
flags - direction and mode flags (combined with |)
Exactly one of IN, OUT, or HIGH_Z must be specified
PULL_UP and PULL_DOWN are mutually exclusive
Raises ArgumentError on invalid flag combinations

# Input with pull-up
button = GPIO.new(2, GPIO::IN | GPIO::PULL_UP)

# Output
led = GPIO.new(25, GPIO::OUT)

Instance Methods

GPIO#read

Read the current pin value.

val = gpio.read  # => 0 or 1

GPIO#write

Set the pin output value.

gpio.write(1)  # set high
gpio.write(0)  # set low

Raises ArgumentError if value is not 0 or 1

GPIO#high? / GPIO#low?

gpio.high?  # => true if read != 0
gpio.low?   # => true if read == 0

GPIO#pin

gpio.pin  # => pin number passed to new

GPIO#setmode

Reconfigure pin direction and mode flags after initialization.

gpio.setmode(GPIO::OUT)

Class Methods

These operate directly on pin numbers without creating an instance.

GPIO.read_at(pin)           # => 0 or 1
GPIO.write_at(pin, val)     # set pin output (0 or 1)
GPIO.set_dir_at(pin, flags) # set direction (IN/OUT/HIGH_Z)
GPIO.pull_up_at(pin)        # enable pull-up
GPIO.pull_down_at(pin)      # enable pull-down
GPIO.open_drain_at(pin)     # enable open-drain

HAL Interface

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

void mrb_gpio_init(uint8_t pin);
void mrb_gpio_set_dir(uint8_t pin, uint8_t flags);
void mrb_gpio_pull_up(uint8_t pin);
void mrb_gpio_pull_down(uint8_t pin);
void mrb_gpio_open_drain(uint8_t pin);
int  mrb_gpio_read(uint8_t pin);
void mrb_gpio_write(uint8_t pin, uint8_t val);

The port sources are compiled automatically when the build configuration includes a matching conf.ports tag.

License

MIT