Module: LittleWire::Digital

Included in:
LittleWire
Defined in:
lib/littlewire/digital.rb

Constant Summary collapse

EnableBulkWrite =

this thing seems to not work good - not ready for real world use

false
BulkWriteDefaultStates =

these firmwares have a default state specified, enabling bulk writing

{ '1.1' => 0b00001000 }
BulkWriteBitmask =

D- usb bit is high, others are low

{ '1.1' => 0b00100111 }

Instance Method Summary collapse

Instance Method Details

#digital_read(*args) ⇒ Object

Read one or more digital values from device pins

The simplest invocation is ‘my_wire.digital_read(:pin1)`, returning a true or false where true is a high (positive) voltage and false is a lower (near ground) voltage

A more advanced invokation is passing several pins as arguments or an array of pins ‘sensor_a, sensor_b = my_wire.digital_read(:pin1, :pin2)` which reads both pins at the exact same instant in just one USB request, returning an array of the results

digital_read works best when the pin is in :input mode. See also #pin_mode



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# File 'lib/littlewire/digital.rb', line 62

def digital_read *args
  raise "Incorrect Arguments" if args.length < 1
  pins = args.flatten
  port = control_transfer(function: :read, dataIn: 1).unpack('c').first
  mapped = pins.map do |pin|
    pin = get_pin(LittleWire::DigitalPinMap, pin)
    ((port >> pin) & 1) == 1 # discover if pin is high or low
  end
  
  if args.length == 1 and (args.first.is_a?(Symbol) or args.first.is_a?(Integer))
    mapped.first
  else
    mapped
  end
end

#digital_write(*args) ⇒ Object

Write one or more digital values to device pins

A simple invokation is ‘my_wire.digital_write(:pin1, true)` setting pin1 to a high logic level. :high and :low can be substituted for true and false, as can :on and :off, :vcc and :gnd or :ground

‘digital_write` can also be called with a hash: `my_wire.digital_write(:pin1 => true)` allowing multiple pins to be set at once. A system for updating all pins simultaniously is being worked on, but is not yet stable, so for now digital_write uses a request for each pin.

Automatically disables PWM and Servo features if you try to write to a pin used by those modules



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# File 'lib/littlewire/digital.rb', line 18

def digital_write *args
  if args.length > 1
    self.digital_write({args[0] => args[1]})
  else
    raise "Incorrect Arguments" unless args.first.respond_to? :to_hash
    hash = args.first.to_hash
    
    #self.hardware_pwm_enabled = false if hash.keys.any? { |pin| LittleWire::HardwarePWMPinMap.has_key? pin }
    #self.software_pwm_enabled = false if hash.keys.any? { |pin| LittleWire::SoftwarePWMPinMap.has_key? pin }
    
    if use_experimental_bulk_write?
      # could cause problems - must do tests when deciding if to enable this or not
      @bulk_write_bitmap ||= 0
      
      hash.each do |pin, state|
        if get_boolean(state)
          @bulk_write_bitmap |= 1 << get_pin(LittleWire::DigitalPinMap, pin)
        else
          @bulk_write_bitmap &= ~(1 << get_pin(LittleWire::DigitalPinMap, pin))
        end
      end
      value = (@bulk_write_bitmap & BulkWriteBitmask[self.version]) | BulkWriteDefaultStates[self.version]
      control_transfer(function: :write, wValue: value)
    else
      hash.each do |pin, state|
        control_transfer(
          function: get_boolean(state) ? :pin_set_high : :pin_set_low,
          wValue: get_pin(LittleWire::DigitalPinMap, pin)
        )
      end
    end
  end
end

#pin_mode(*args) ⇒ Object

Set the mode of one or more device pins

A simple form is ‘my_wire.pin_mode(:pin1, :input)` setting pin1 to input mode. Multiple pins can be set using `my_wire.pin_mode(:pin1 => :input, :pin2 => :output)`

:input mode leaves the pin disconnected if ‘digital_write`n to false, or connected via a 20kohm resistor to 5 volts if `digital_write` to true.

:output mode connects the pin directly to 5 volts when ‘digital_write`n to true and connects it to ground when digitally written to false. Be careful not to create short circuits as these may damage your LittleWire.



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# File 'lib/littlewire/digital.rb', line 89

def pin_mode *args
  if args.length == 2
    self.pin_mode( args[0] => args[1] )
  else
    raise if args.length != 1 or !args.first.is_a?(Hash)
    
    modes = {
      :input => :pin_set_input, :in => :pin_set_input,
      :output => :pin_set_output, :out => :pin_set_output
    }
    args.first.each do |pin, mode|
      raise "Unknown mode #{mode.inspect}" unless modes[mode.to_sym]
      control_transfer(function: modes[mode.to_sym], wValue: get_pin(LittleWire::DigitalPinMap, pin))
    end
  end
end