mlx90614.py

"""
MicroPython MLX90614 IR temperature sensor driver
https://github.com/mcauser/micropython-mlx90614

MIT License
Copyright (c) 2016 Mike Causer

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

import ustruct

class SensorBase:

	def read16(self, register):
		data = self.i2c.readfrom_mem(self.address, register, 2)
		return ustruct.unpack('<H', data)[0]

	def read_temp(self, register):
		temp = self.read16(register);
		# apply measurement resolution (0.02 degrees per LSB)
		temp *= .02;
		# Kelvin to Celcius
		temp -= 273.15;
		return temp;

	def read_ambient_temp(self):
		return self.read_temp(self._REGISTER_TA)

	def read_object_temp(self):
		return self.read_temp(self._REGISTER_TOBJ1)

	def read_object2_temp(self):
		if self.dual_zone:
			return self.read_temp(self._REGISTER_TOBJ2)
		else:
			raise RuntimeError("Device only has one thermopile")

	@property
	def ambient_temp(self):
		return self.read_ambient_temp()

	@property
	def object_temp(self):
		return self.read_object_temp()

	@property
	def object2_temp(self):
		return self.read_object2_temp()

class MLX90614(SensorBase):

	_REGISTER_TA = 0x06
	_REGISTER_TOBJ1 = 0x07
	_REGISTER_TOBJ2 = 0x08

	def __init__(self, i2c, address=0x5a):
		self.i2c = i2c
		self.address = address
		_config1 = i2c.readfrom_mem(address, 0x25, 2)
		_dz = ustruct.unpack('<H', _config1)[0] & (1<<6)
		self.dual_zone = True if _dz else False

class MLX90615(SensorBase):

	_REGISTER_TA = 0x26
	_REGISTER_TOBJ1 = 0x27

	def __init__(self, i2c, address=0x5b):
		self.i2c = i2c
		self.address = address
		self.dual_zone = False