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https://github.com/khoulihan/micropython-tmp102

Support for the TI tmp102 I2C temperature sensor.
https://github.com/khoulihan/micropython-tmp102

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Support for the TI tmp102 I2C temperature sensor.

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README 

        
micropython-tmp102

==================



Implements support for the Texas Instruments tmp102 temperature sensor.



Copyright (c) 2014 by Kevin Houlihan



License: MIT, see LICENSE for more details.



Usage

=====



The main functionality of this package is contained in the Tmp102 class, which

wraps an I2C object from the pyb or machine modules to configure and read from a

tmp102 device at a specific address.



At it's most basic, the class can be can be initialized with an I2C bus object and

an address, and then the temperature can be read periodically from the temperature

property:



    from pyb import I2C

    from tmp102 import Tmp102

    bus = I2C(1, I2C.MASTER)

    sensor = Tmp102(bus, 0x48)

    print(sensor.temperature)



Or for the I2C class in the machine module:



    from machine import I2C

    from tmp102 import Tmp102

    bus = I2C(1)

    sensor = Tmp102(bus, 0x48)

    print(sensor.temperature)



The temperature will be in celsius by default.



Conversion Rate

===============



By default, the temperature will be updated at 4Hz. The rate of updates can be

set to one of four frequencies by setting the conversion_rate property, or by

passing a conversion_rate named argument to the constructor. The *conversionrate*

module must be imported to enable this functionality:

    

    from tmp102 import Tmp102

    import tmp102.conversionrate

    sensor = Tmp102(

        bus,

        0x48,

        conversion_rate=Tmp102.CONVERSION_RATE_1HZ

    )

    sensor.conversion_rate = Tmp102.CONVERSION_RATE_QUARTER_HZ  # 0.25Hz



The available rates are:



    Tmp102.CONVERSION_RATE_QUARTER_HZ

    Tmp102.CONVERSION_RATE_1HZ

    Tmp102.CONVERSION_RATE_4HZ

    Tmp102.CONVERSION_RATE_8HZ



Extended Mode

=============



By default, the temperature value is stored as 12 bits, for a maximum reading of

128C. Extended mode uses 13 bits instead, allowing a reading up to 150C. Extended

mode can be enabled by setting the extended_mode property or passing an extended_mode

named argument to the constructor. The *extendedmode* module must be imported to enable

this functionality.



    from tmp102 import Tmp102

    import tmp102.extendedmode

    sensor = Tmp102(

        bus,

        0x48,

        extended_mode=True

    )

    sensor.extended_mode = True



Shutdown and One-Shot Conversions

=================================



When temperature readings are not required for an extended period, the device can

be shut down to save power. Only the serial interface is kept awake to allow the

device to be woken up again. The device can be shut down and awoken by setting the

shutdown property appropriately. The *shutdown* module must be imported to enable

this functionality.



    sensor.shutdown = True

    # sensor.temperature will not be updated again until the device is awoken.

    pyb.delay(60000)

    sensor.shutdown = False

    # sensor.temperature will again be updated at the previously configured frequency.



Note that there is a delay between when the device receives the instruction to wake

up and when the first reading becomes available.



If the device is shut down and only a single reading is required, it is not

necessary to toggle the shutdown and make the device fully active again in order

to get a reading. A "one-shot" conversion can be initiated by calling the

initiate_conversion method. The progress of the conversion can be monitored through

the conversion_ready property. The *oneshot* module must be imported to enable this

functionality.



    sensor.initiate_conversion()

    while not sensor.conversion_ready:

        pyb.delay(10)

    temp = sensor.temperature



The device remains shutdown after this process.



One-shot conversions allow the temperature to be polled at frequencies much

longer than the four pre-set conversion rates without wasting power. To facilitate

this mode of operation, the device can be intitialized in shutdown mode by passing

a shutdown named argument to the constructor:



    sensor = Tmp102(bus, 0x48, shutdown=True)



Thermostat Mode and Alerts

==========================



The sensor has a feature to set and unset a flag based on high and low temperatures

being reached. It can also generate an SMBus interrupt when operating in a

certain mode. I'm not sure if this interrupt could be handled by the hardware,

but it is definitely not supported by this module.



The alert flag can be read on the alert property, and can take the values

Tmp102.ALERT_HIGH or Tmp102.ALERT_LOW. The various configuration flags and values

supported by the device can all be set through properties of the object or

arguments to the constructor, but their semantics are best described by the

datasheet of the sensor: http://www.ti.com/lit/ds/symlink/tmp102.pdf



The alert module must be imported to use any of these features.



    from tmp102 import Tmp102

    import tmp102.alert

    sensor = Tmp102(

        bus,

        0x48,

        alert_polarity=Tmp102.ALERT_HIGH,

        thermostat_mode=Tmp102.COMPARATOR_MODE,

        fault_queue_length=Tmp102.FAULT_QUEUE_4,

        thermostat_high_temperature=35.0,

        thermostat_low_temperature=34.0

    )



    sensor.alert_polarity = Tmp102.ALERT_LOW  #Default

    sensor.alert_polarity = Tmp102.ALERT_HIGH



    sensor.thermostat_mode = Tmp102.COMPARATOR_MODE  # Default

    sensor.thermostat_mode = Tmp102.INTERRUPT_MODE



    sensor.fault_queue_length = Tmp102.FAULT_QUEUE_1  # Default

    sensor.fault_queue_length = Tmp102.FAULT_QUEUE_2

    sensor.fault_queue_length = Tmp102.FAULT_QUEUE_4

    sensor.fault_queue_length = Tmp102.FAULT_QUEUE_6



Temperature Scales/Units

========================



By default, all temperatures are in celsius. If another scale/unit is preferred,

a convertor can be provided to the constructor. Fahrenheit and Kelvin convertor

classes are included in the *convertors* module.



    sensor = Tmp102(

        bus, 

        0x48, 

        temperature_convertor=Fahrenheit()

    )



A custom convertor can be provided as an object with this signature:



    class ScaleUnit(object):

        def convert_from(self, temperature):

            '''

            Convert FROM the custom unit TO celsius.

            '''

            ...

            return new_temp



        def convert_to(self, temperature):

            '''

            Convert TO the custom unit FROM celsius.

            '''

            ...

            return new_temp