Class: I2C::Dev

Inherits:
Object
  • Object
show all
Defined in:
lib/i2c/backends/i2c-dev.rb

Constant Summary collapse

I2C_SLAVE =

see i2c-dev.h

0x0703

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.create(device_path) ⇒ Object

Raises:

  • (Errno::ENOENT) 


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# File 'lib/i2c/backends/i2c-dev.rb', line 14

def self.create(device_path)
  raise Errno::ENOENT, "Device #{device_path} not found." unless File.exists?(device_path)
  @instances ||= Hash.new
  @instances[device_path] = Dev.new(device_path) unless @instances.has_key?(device_path)
  @instances[device_path]
end

Instance Method Details

#read(address, size, *params) ⇒ Object

this sends *params as the write function and then tries to read size bytes. The result is a String which can be treated with String#unpack afterwards



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# File 'lib/i2c/backends/i2c-dev.rb', line 40

def read(address, size, *params)
  ret = ""
  write(address, *params)
  ret = @device.sysread(size)
  return ret
end

#read_byte(address) ⇒ Object

Read a byte from the current address. Return a one char String which can be treated with String#unpack



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# File 'lib/i2c/backends/i2c-dev.rb', line 49

def read_byte(address)
  ret=""
  @device.ioctl(I2C_SLAVE,address)
  ret=@device.sysread(1)
  return ret
end

#write(address, *params) ⇒ Object

sends every param, begining with params[0] If the current param is a Fixnum, it is treated as one byte. If the param is a String, this string will be send byte by byte. You can use Array#pack to create a string from an array For Fixnum there is a convinient function to_short which transforms the number to a string this way: 12345.to_short == [12345].pack(“s”)



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# File 'lib/i2c/backends/i2c-dev.rb', line 27

def write(address, *params)
  data = String.new
  data.force_encoding("US-ASCII")
  params.each do |value|
    data << value
  end
  @device.ioctl(I2C_SLAVE, address)
  @device.syswrite(data)
end