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Software/Ruby/grove_pi.rb

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+#!/usr/bin/env ruby
+
+module GrovePi
+  require 'i2c'
+  require 'i2c/driver/i2c-dev'
+
+  # Commands.
+  CMD_READ_DIGITAL = 1
+  CMD_WRITE_DIGITAL = 2
+  CMD_READ_ANALOG = 3
+  CMD_WRITE_ANALOG = 4
+  CMD_PIN_MODE = 5
+  CMD_READ_FIRMWARE_VERSION = 8
+
+  # Arduino pin mappings.
+  A0 = 14
+  A1 = 15
+  A2 = 16
+
+  PINS_ANALOG = [A0, A1, A2]
+
+  D2 = 2
+  D3 = 3
+  D4 = 4
+  D5 = 5
+  D6 = 6
+  D7 = 7
+  D8 = 8
+
+  PINS_DIGITAL = [D2, D3, D4, D5, D6, D7, D8]
+
+  # Pin modes.
+  PIN_MODE_IN = 0
+  PIN_MODE_OUT = 1
+
+  # Configuration settings.
+  CONFIG_RETRIES = 10
+  GROVE_PI_I2C_SLAVE_ADDRESS = 4
+
+  # The initialized I2C object.
+  @_i2c_grove_pi = nil
+
+  # Storage for I2C slave addresses present on ports I2C-1, I2C-2 or I2C-3.
+  @_i2c_slave_addresses = Hash.new
+
+  # Internal functions.
+  #
+  # These functions are not intended to be used directly by the user but by the
+  # functions which are exposed to the user.
+  def self._grove_pi_discover()
+    begin
+      i2c_device_files = Dir['/dev/i2c-*']
+
+      if i2c_device_files.length < 1
+        return false, nil
+      end
+
+      # Iterate over I2C device files.
+      for f in i2c_device_files
+        device_file = f
+        f = f.strip
+        f.slice! '/dev/i2c-'
+        lines = %x(#{'i2cdetect -y ' + Integer(f).to_s}).split("\n")
+
+        # Get rid of the first line.
+        lines.shift
+
+        if lines.length < 1
+          next
+        end
+
+        # Process i2cdetect command output for the I2C device file.
+        for i in 0..lines.length - 1
+          line = lines[i].strip
+          line = line.split ':'
+
+          if line.length != 2
+            next
+          end
+
+          for i2c_address in line[1].split(' ')
+            begin
+              if Integer(i2c_address) == GROVE_PI_I2C_SLAVE_ADDRESS
+                return true, device_file.strip
+              end
+            rescue
+              next
+            end
+          end
+        end
+      end
+    rescue
+      return false, nil
+    end
+
+    return false, nil
+  end
+
+  def self._grove_pi_init()
+    status, i2c_device_file = self._grove_pi_discover
+
+    if status && i2c_device_file != nil
+      return I2CDevice.new address: GROVE_PI_I2C_SLAVE_ADDRESS,
+                           driver: I2CDevice::Driver::I2CDev.new(i2c_device_file)
+    else
+      return nil
+    end
+  end
+
+  def self._ensure_init()
+    if @_i2c_grove_pi == nil
+      @_i2c_grove_pi = self._grove_pi_init
+
+      if @_i2c_grove_pi == nil
+        raise 'No GrovePi found.'
+      end
+    end
+  end
+
+  def self._set_pin_mode(pin, mode)
+    self._ensure_init
+    @_i2c_grove_pi.i2cset @_i2c_grove_pi.address, CMD_PIN_MODE, pin, mode, 0
+  end
+
+  def self._read_analog(pin)
+    self._ensure_init
+    @_i2c_grove_pi.i2cset @_i2c_grove_pi.address, CMD_READ_ANALOG, pin, 0, 0
+    bytes = @_i2c_grove_pi.i2cget(@_i2c_grove_pi.address, 3).chars
+    return (bytes[1].ord * 256) + bytes[2].ord
+  end
+
+  def self._write_analog(pin, value)
+    self._ensure_init
+    @_i2c_grove_pi.i2cset @_i2c_grove_pi.address, CMD_WRITE_ANALOG, pin, value, 0
+  end
+
+  def self._read_digital(pin)
+    self._ensure_init
+    @_i2c_grove_pi.i2cset @_i2c_grove_pi.address, CMD_READ_DIGITAL, pin, 0, 0
+    return @_i2c_grove_pi.i2cget(@_i2c_grove_pi.address, 2).chars[0].ord
+  end
+
+  def self._write_digital(pin, value)
+    self._ensure_init
+    @_i2c_grove_pi.i2cset @_i2c_grove_pi.address, CMD_WRITE_DIGITAL, pin, value, 0
+  end
+
+  # Functions exposed to the user.
+
+  # Analog read functions.
+  def self.read_analog(pin)
+    if !PINS_ANALOG.include? pin
+      raise 'Invalid analog pin.'
+    end
+
+    for i in 0..CONFIG_RETRIES - 1
+      begin
+        self._set_pin_mode pin, PIN_MODE_IN
+        return self._read_analog pin
+      rescue Errno::EREMOTEIO
+        next
+      end
+    end
+  end
+
+  # Analog write functions (PWM on digital pins D3, D5 and D6).
+  def self.write_analog(pin, value)
+    if !PINS_DIGITAL.include? pin
+      raise 'Invalid analog pin. Note: PWM based analog write is applicable on digital ports.'
+    end
+
+    for i in 0..CONFIG_RETRIES - 1
+      begin
+        self._set_pin_mode pin, PIN_MODE_OUT
+        self._write_analog pin, value
+        return
+      rescue Errno::EREMOTEIO
+        next
+      end
+    end
+  end
+
+  # Digital read function.
+  def self.read_digital(pin)
+    if !PINS_DIGITAL.include? pin
+      raise 'Invalid digital pin.'
+    end
+
+    for i in 0..CONFIG_RETRIES - 1
+      begin
+        self._set_pin_mode pin, PIN_MODE_IN
+        return self._read_digital pin
+      rescue Errno::EREMOTEIO
+        next
+      end
+    end
+  end
+
+  # Digital write function.
+  def self.write_digital(pin, value)
+    if !PINS_DIGITAL.include? pin
+      raise 'Invalid digital pin.'
+    end
+
+    for i in 0..CONFIG_RETRIES - 1
+      begin
+        self._set_pin_mode pin, PIN_MODE_OUT
+        self._write_digital pin, value
+        return
+      rescue Errno::EREMOTEIO
+        next
+      end
+    end
+  end
+
+  # Functions for reading and writing I2C slaves connected to
+  # I2C-1, I2C-2 or I2C-3 ports of the GrovePi.
+  def self.read_grove_pi_i2c(i2c_slave_address, length)
+    _ensure_init
+
+    if !@_i2c_slave_addresses.key?(i2c_slave_address)
+      path =
+        @_i2c_grove_pi.instance_variable_get(:@driver)
+                      .instance_variable_get(:@path)
+
+      @_i2c_slave_addresses[i2c_slave_address] = I2CDevice.new address: i2c_slave_address,
+                                                               driver: I2CDevice::Driver::I2CDev.new(path)
+    end
+
+    bytes = []
+    _bytes = @_i2c_slave_addresses[i2c_slave_address].i2cget(i2c_slave_address, length).chars
+
+    for b in _bytes
+      bytes << b.ord
+    end
+
+    return bytes
+  end
+
+  def self.write_grove_pi_i2c(i2c_slave_address, *data)
+    _ensure_init
+
+    if !@_i2c_slave_addresses.key?(i2c_slave_address)
+      path =
+        @_i2c_grove_pi.instance_variable_get(:@driver)
+                      .instance_variable_get(:@path)
+
+      @_i2c_slave_addresses[i2c_slave_address] = I2CDevice.new address: i2c_slave_address,
+                                                               driver: I2CDevice::Driver::I2CDev.new(path)
+    end
+
+    @_i2c_slave_addresses[i2c_slave_address].i2cset i2c_slave_address, *data
+  end
+
+  # Miscellaneous functions.
+  def self.read_firmware_version()
+    for i in 0..CONFIG_RETRIES - 1
+      begin
+        self._ensure_init
+        @_i2c_grove_pi.i2cset @_i2c_grove_pi.address, CMD_READ_FIRMWARE_VERSION, 0, 0, 0
+        bytes = @_i2c_grove_pi.i2cget(@_i2c_grove_pi.address, 4).chars
+        return [bytes[1].ord, bytes[2].ord, bytes[3].ord]
+      rescue Errno::EREMOTEIO
+        next
+      end
+    end
+  end
+
+  # TODO: Implement rest of the commands that are supported by the firmware.
+end