Module: Denko::AnalogIO::ADS111X

Includes:
Behaviors::BoardProxy, Behaviors::Reader
Included in:
ADS1115, ADS1118
Defined in:
lib/denko/analog_io/ads111x.rb

Constant Summary collapse

PGA_SETTINGS =

Bitmask Full scale voltage

[  # Bitmask   Full scale voltage
  0.0001875,      # 0b000     6.144 V
  0.000125,       # 0b001     4.095 V
  0.0000625,      # 0b010     2.048 V (default)
  0.00003125,     # 0b011     1.024 V
  0.000015625,    # 0b100     0.512 V
  0.0000078125,   # 0b101     0.256 V
  0.0000078125,   # 0b110     0.256 V
  0.0000078125,   # 0b111     0.256 V
]
PGA_RANGE = 
(0..7).to_a
SAMPLE_TIMES =

Sample rate bitmask maps to sample time in seconds.

[  # Bitmask
  0.125,          # 0b000
  0.0625,         # 0b001
  0.03125,        # 0b010
  0.015625,       # 0b011
  0.0078125,      # 0b100 (default)
  0.004,          # 0b101
  0.002105263,    # 0b110
  0.00116279,     # 0b111
]
SAMPLE_RATE_RANGE =

0b111

(0..7).to_a
WAIT_TIMES =

Wait times need to be slightly longer than the actual sample times.

SAMPLE_TIMES.map { |time| time + 0.0005 }
MUX_SETTINGS =

Mux bits map to array of form [positive input, negative input].

{
  0b000 => [0, 1],
  0b001 => [0, 3],
  0b010 => [1, 3],
  0b011 => [2, 3],
  0b100 => [0, nil],
  0b101 => [1, nil],
  0b110 => [2, nil],
  0b111 => [3, nil],
}

Constants included from Behaviors::Reader

Behaviors::Reader::READ_WAIT_TIME

Constants included from Behaviors::Lifecycle

Behaviors::Lifecycle::CALLBACK_METHODS

Instance Attribute Summary collapse

Attributes included from Behaviors::State

#state

Instance Method Summary collapse

Methods included from Behaviors::BoardProxy

#analog_read_high, #analog_write_high, #convert_pin, #high, #low, #set_pin_mode, #start_read

Methods included from Behaviors::Subcomponents

#add_component, #add_hw_i2c, #add_hw_spi, #add_single_pin, #components, #hw_i2c_comps, #hw_spi_comps, #remove_component, #remove_hw_i2c, #remove_hw_spi, #remove_single_pin, #single_pin_components

Methods included from Behaviors::Reader

#_read, #read, #read_busy?, #read_nb, #read_raw, #read_using, #update

Methods included from Behaviors::Callbacks

#add_callback, #callbacks, #remove_callback, #update

Methods included from Behaviors::State

#update_state

Methods included from Behaviors::Lifecycle

included

Instance Attribute Details

#active_gain ⇒ Object

Returns the value of attribute active_gain.



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# File 'lib/denko/analog_io/ads111x.rb', line 8

def active_gain
  @active_gain
end

#active_pin ⇒ Object

Returns the value of attribute active_pin.



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# File 'lib/denko/analog_io/ads111x.rb', line 8

def active_pin
  @active_pin
end

#config_register ⇒ Object

Returns the value of attribute config_register.



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# File 'lib/denko/analog_io/ads111x.rb', line 8

def config_register
  @config_register
end

Instance Method Details

#analog_listen(pin, divider = nil) ⇒ Object

Raises:

  • (StandardError) 


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# File 'lib/denko/analog_io/ads111x.rb', line 124

def analog_listen(pin, divider=nil)
  raise StandardError, "ADS111X does not implement #listen for subcomponents. Use #read or #poll instead"
end

#analog_read(pin, negative_pin = nil, gain = nil, sample_rate = nil) ⇒ Object 



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# File 'lib/denko/analog_io/ads111x.rb', line 72

def analog_read(pin, negative_pin=nil, gain=nil, sample_rate=nil)
  # Wrap in mutex so calls and callbacks are atomic.
  mutex.lock

  # Default gain and sample rate.
  gain        ||= 0b010
  sample_rate ||= 0b100

  # Set these for callbacks.
  self.active_pin   = pin
  self.active_gain  = gain

  # Set gain in upper config register.
  raise ArgumentError "wrong gain: #{gain.inspect} given for ADS111X" unless PGA_RANGE.include?(gain)
  config_register[0] = self.class::BASE_MSB | (gain << 1)

  # Set mux bits in upper config register.
  mux_bits = pins_to_mux_bits(pin, negative_pin)
  config_register[0] = config_register[0] | (mux_bits << 4)

  # Set sample rate in lower config_register.
  raise ArgumentError "wrong sample_rate: #{sample_rate.inspect} given for ADS111X" unless SAMPLE_RATE_RANGE.include?(sample_rate)
  config_register[1] = self.class::BASE_LSB | (sample_rate << 5)

  result = read(config_register)
  mutex.unlock

  result
end

#enable_proxy ⇒ Object

Mimic Board#update, but inside a callback, wrapped by #update.



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# File 'lib/denko/analog_io/ads111x.rb', line 56

def enable_proxy
  self.add_callback(:board_proxy) do |value|
    components.each do |component|
      if active_pin == component.pin
        component.volts_per_bit = PGA_SETTINGS[active_gain]
        component.update(value)
      end
    end
  end
end

#mutex ⇒ Object 



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# File 'lib/denko/analog_io/ads111x.rb', line 131

def mutex
  # mruby doesn't have Thread or Mutex, so only stub there.
  @mutex ||= Denko.mruby? ? Denko::MutexStub.new : Mutex.new
end

#pins_to_mux_bits(pin, negative_pin) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/denko/analog_io/ads111x.rb', line 102

def pins_to_mux_bits(pin, negative_pin)
  # Pin 1 is negative input. Only pin 0 can be read.
  if negative_pin == 1
    raise ArgumentError, "given pin: #{pin.inspect} cannot be used when pin 1 is negative input, only 0" unless pin == 0
    return 0b000
  end

  # Pin 3 is negative input. Pins 0..2 can be read.
  if negative_pin == 3
    raise ArgumentError, "given pin: #{pin.inspect} cannot be used when pin 3 is negative input, only 0..2" unless [0,1,2].include? pin
    return 0b001 + pin
  end

  # No negative input. Any pin from 0 to 3 can be read.
  unless negative_pin
    raise ArgumentError, "given pin: #{pin.inspect} is out of range 0..3" unless [0,1,2,3].include? pin
    return (0b100 + pin)
  end

  raise ArgumentError, "only pins 1 and 3 can be used as negative input"
end

#pre_callback_filter(bytes) ⇒ Object 



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# File 'lib/denko/analog_io/ads111x.rb', line 67

def pre_callback_filter(bytes)
  # Pack the 2 bytes into a string, then unpack as big-endian int16.
  value = bytes.pack("C*").unpack("s>")[0]
end

#stop_listener(pin) ⇒ Object 



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# File 'lib/denko/analog_io/ads111x.rb', line 128

def stop_listener(pin)
end