Get temperature from ADT7410

adt7410.rb

#!/usr/bin/env ruby

# Sample Output
# pi@raspberrypi:~ $ ruby adt7410.rb
# Path: /dev/i2c-1
# Temp:  29.26

require 'i2c'

I2C_RETRIES     = 0x0701
I2C_TIMEOUT     = 0x0702
I2C_SLAVE       = 0x0703
I2C_SLAVE_FORCE = 0x0706
I2C_TENBIT      = 0x0704
I2C_FUNCS       = 0x0705
I2C_RDWR        = 0x0707
I2C_SMBUS       = 0x0720
I2C_UDELAY      = 0x0705
I2C_MDELAY      = 0x0706

def get_path(path=nil)
  if path.nil?
    path = Dir.glob("/dev/i2c-*").sort.last
  end

  unless File.exist?(path)
    raise I2CDevice::I2CIOError, "/dev/i2c-0 is required"
  end
  path
end

# Interface of I2CDevice::Driver
def i2cget(address, param, length)
  i2c = File.open(@path, "r+")
  i2c.ioctl(I2C_SLAVE, address)
  i2c.syswrite(param.chr) unless param.nil?
  ret = i2c.sysread(length)
  i2c.close
  ret
rescue Errno::EIO => e
  raise I2CDevice::I2CIOError, e.message
end

# Interface of I2CDevice::Driverdef i2cset(address, *data)
def i2cset(address, *data)
  i2c = File.open(@path, "r+")
  i2c.ioctl(I2C_SLAVE, address)
  i2c.syswrite(data.pack("C*"))
  i2c.close
rescue Errno::EIO => e
  raise I2CDevice::I2CIOError, e.message
end

@path = get_path
puts "Path: " + @path

@device  = I2C.create @path
@address = 0x48

data = i2cget(@address, 0x00, 2).unpack("C*")
temp = data[0] << 8 | data[1]
puts "Temp: %6.2f" % (temp / 128.0)