Module: NXT::Protocols::I2C

Defined in:
lib/nxt/protocols/i2c.rb

Overview

Communication to the NXT brick for digital sensors is done using the I2C protocol. This module implements communication in that fashion, abstracing the messages we wish to send from the underlying protocol for ease-of-use.

Constant Summary collapse

COMMAND_IDENTIFIER = 
{
  ls_get_status: 0x0E,
  ls_write: 0x0F,
  ls_read: 0x10
}.freeze
I2C_HEADER = 
0x02
I2C_CONSTANT_OPS =

Format is I2C address, followed by the number of bytes expected in the response.

{
  read_version: [0x00, 8],
  read_product_id: [0x08, 8],
  read_sensor_type: [0x10, 8],
  read_factory_zero: [0x11, 1],
  read_factory_scale_factor: [0x12, 1],
  read_factory_scale_divisor: [0x13, 1],
  read_measurement_units: [0x14, 7]
}.freeze
I2C_VARIABLE_OPS =

Format is the I2C address (all variable operations expect a 1 byte reponse).

{
  read_continuous_measurements_interval: 0x40,
  read_command_state: 0x41,
  read_measurement_byte_zero: 0x42,
  read_measurement_byte_one: 0x43,
  read_measurement_byte_two: 0x44,
  read_measurement_byte_three: 0x45,
  read_measurement_byte_four: 0x46,
  read_measurement_byte_five: 0x47,
  read_measurement_byte_six: 0x48,
  read_measurement_byte_seven: 0x49,
  read_actual_zero: 0x50,
  read_actual_scale_factor: 0x51,
  read_actual_scale_divisor: 0x52
}.freeze
I2C_COMMANDS =

Format is I2C address, followed by the command. If the array is only one member large, then the second byte is instead a value passed at run-time, eg. the length of the interval to run the continuous measuring on the ultrasonic sensor for.

{
  off_command: [0x41, 0x00],
  single_shot_command: [0x41, 0x01],
  continuous_measurement_command: [0x41, 0x02],
  event_capture_command: [0x41, 0x03],
  request_warm_reset: [0x41, 0x04],
  set_continuous_measurement_interval: [0x40],
  set_actual_zero: [0x50],
  set_actual_scale_factor: [0x51],
  set_actual_scale_divisor: [0x52]
}.freeze

Class Method Summary collapse

Class Method Details

.method_missing(name, *args) ⇒ Object 



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# File 'lib/nxt/protocols/i2c.rb', line 62

def self.method_missing(name, *args)
  if I2C_CONSTANT_OPS.key?(name)
    run_constant_op(name)
  elsif I2C_VARIABLE_OPS.key?(name)
    run_variable_op(name)
  elsif I2C_COMMANDS.key?(name)
    run_command(name, *args)
  else
    super
  end
end

.respond_to_missing?(name, include_private = false) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nxt/protocols/i2c.rb', line 74

def self.respond_to_missing?(name, include_private = false)
  I2C_CONSTANT_OPS.key?(name) ||
    I2C_VARIABLE_OPS.key?(name) ||
    I2C_COMMANDS.key?(name) ||
    super
end