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mruby_io_GPIO_en.md

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GPIO

  • A class that supports general-purpose digital input/output functionality.
  • Generally, it is intended for controlling the input or output of a single physical pin.

Class method

GPIO.setmode( pin, params ) -> nil

  • Specify the physical pin indicated by "pin" and change the mode of the GPIO.
  • Refer to the constructor for other information.

Example of use:

# Set pin number 1 output.
GPIO.setmode( 1, GPIO::OUT )

# Set B1 pin to input, with internal pull-up. (for PIC, etc.)
GPIO.setmode( "B1", GPIO::IN|GPIO::PULL_UP )

read_at( pin ) -> Integer

  • Returns the value read from the specified pin as either 0 or 1.
  • When reading from the pin set for output, if the hardware permits, the actual value should be read and returned instead of the set value.

Example of use:

GPIO.setmode( 1, GPIO::IN )
v1 = GPIO.read_at( 1 )          # read from pin 1.

high_at?( pin ) -> bool

  • Return true If the value read from the specified pin is high (==1)

Example of use:

if GPIO.high_at?( 1 )

low_at?( pin ) -> bool

  • If the value loaded from the specified pin is low-level (== 0), return true.

Example of use:

if GPIO.low_at?( 1 )

write_at( pin, integer_data )

  • Output a value to the specified pin.
  • The value must be specified as either 0 or 1.
  • If the data is out of range (i.e. not 0 or 1), a RangeError will occur.

Example of use:

GPIO.setmode( 1, GPIO::OUT )
GPIO.write_at( 1, 0 )      # output zero to pin 1.

Constructor

GPIO.new( pin, params )

  • Specify the physical pin indicated by the pin and generate a GPIO object.
  • At the same time, specify a param to indicate the mode, such as input/output direction.
  • The pin is typically specified as an integer, but other methods (such as "B1" in PIC) may be used.
  • Although one bit is the basic unit, pin specification that combines multiple bits may be necessary depending on the device.
  • Use the following constants for param and specify them connected by |.
  • IN, OUT, or HIGH_Z instruction is mandatory, and an ArgumentError will occur if it is absent.

Constants:

GPIO::IN            # Set as input
GPIO::OUT           # Set as output
GPIO::HIGH_Z        # Set as high impedance
GPIO::PULL_UP       # Enable internal pull-up
GPIO::PULL_DOWN     # Enable internal pull-down
GPIO::OPEN_DRAIN    # Set to open-drain mode

Usage Example

# Set GPIO pin 1 as output.
gpio1 = GPIO.new(1, GPIO::OUT)

# Set B1 pin as input with internal pull-up (for PIC, etc.).
gpio1 = GPIO.new("B1", GPIO::IN|GPIO::PULL_UP)

Instance methods

read() -> Integer

  • Return the loaded value as 0 or 1.
  • It can be any integer only when implementing multiple bit processing.
  • If reading from the pin set for output, the hardware should read and return the actual value if possible, not the set value.

Example of use:

v1 = gpio1.read()

high?() -> bool

  • If the loaded value is high level (==1), it returns true.

Example of use:

if gpio1.high?()

low?() -> bool

If the loaded value is low-level (==0), return true.

Example of use:

if gpio1.low?()

write( integer_data )

  • Specify the value to output to the pin as either 0 or 1.
  • Only in the case of implementation that handles multiple bits collectively, indicate with any integer value.

Example of use:

gpio1.write( 1 )

setmode( param ) -> nil

  • Change the GPIO mode at any timing.
  • When IN, OUT, or HIGH_Z is specified while PULL_UP or other settings have already been set, the previous settings will be invalidated.

Example of use:

# Enable internal pullup.
gpio1.setmode( GPIO::PULL_UP )

# Switch to input and enable internal pullup.
gpio1.setmode( GPIO::IN|GPIO::PULL_UP )