The Harucom Board carries eight tactile buttons. Board::Pad reads them from Ruby, which is handy for games or for running the board without a keyboard attached.

The buttons are split into two groups of four, each wired to one ADC pin. The buttons in a group sit behind different resistors, so the combination of buttons pressed changes the voltage that the ADC reads.

Group	GPIO	Constant
Left four	GPIO 28	`Board::PAD0_PIN`
Right four	GPIO 29	`Board::PAD1_PIN`

Getting Started

require "board/pad"

pad = Board::Pad.new(Board::PAD0_PIN)

loop do
  pad.read

  puts "right" if pad.right?
  puts "up"    if pad.up?
  puts "down"  if pad.down?
  puts "left"  if pad.left?

  sleep_ms 50
end

read samples the current state. After that, right? and friends tell you which buttons are held.

Use one Board::Pad per group when you need both.

left_pad  = Board::Pad.new(Board::PAD0_PIN)
right_pad = Board::Pad.new(Board::PAD1_PIN)

Methods

Board::Pad.new(pin, calibration:, max_buttons:)

pad = Board::Pad.new(Board::PAD0_PIN)

Takes the ADC pin. calibration and max_buttons are optional (see Multiple Presses and Calibration).

Board::Pad#read

pad.read

Samples the buttons and updates the internal state. It returns self, so calls can be chained.

puts "up" if pad.read.up?

Board::Pad#pressed?(button)

pad.pressed?(Board::Pad::UP)   #=> true / false

Reports whether a button is held.

Board::Pad#right? / #up? / #down? / #left?

pad.up?

Shorthand for pressed?.

Board::Pad#raw

pad.raw   #=> 2000

Returns the raw ADC reading (0 to 4095). With no button held it sits near 4095.

Board::Pad#state

pad.state   #=> 5

Returns the pressed buttons as a bitmask. For example 5 means right (bit 0) and down (bit 2) are held.

Button Constants

Constant	Value	Direction
`Board::Pad::RIGHT`	0	Right
`Board::Pad::UP`	1	Up
`Board::Pad::DOWN`	2	Down
`Board::Pad::LEFT`	3	Left

Multiple Presses and Calibration

Because four buttons share one ADC pin, the readings crowd together as more buttons are held at once. By default two simultaneous presses are distinguished.

pad = Board::Pad.new(Board::PAD0_PIN, max_buttons: 3)

calibration takes the raw value of each button pressed on its own, in the order right, up, down, left. The default is [2000, 2760, 3300, 3646]. If board-to-board variation throws the detection off, read the actual values with raw and pass your own.

pad = Board::Pad.new(Board::PAD0_PIN, calibration: [1980, 2740, 3290, 3640])

pad_demo shows the button state on screen.

Board::Pad (Button Input)

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