adding methods to setup critical/upper and lower temperatures

README.rst

@@ -61,15 +61,15 @@ Getting the temperature in Celsius is easy! First, import all of the pins from
 the board, board.I2C() for native I2C communication and the thermometer library
 itself.
 
-.. code-block:: python
+.. code-block:: python3
 
-  from board import *
+  import board
   import adafruit_mcp9808
 
 Next, initialize the I2C bus in a with statement so it always gets shut down ok.
 Then, construct the thermometer class:
 
-.. code-block:: python
+.. code-block:: python3
 
   # Do one reading
   with i2c = board.I2C() as i2c:

adafruit_mcp9808.py

@@ -1,5 +1,5 @@
 # SPDX-FileCopyrightText: 2017 Scott Shawcroft for Adafruit Industries
-#
+# SPDX-FileCopyrightText: 2021 Jose David Montoya
 # SPDX-License-Identifier: MIT
 
 """
@@ -8,38 +8,60 @@
 
 CircuitPython library to support MCP9808 high accuracy temperature sensor.
 
-* Author(s): Scott Shawcroft
+* Author(s): Scott Shawcroft, Jose David M.
 
 Implementation Notes
 --------------------
 
 **Hardware:**
 
-* Adafruit `MCP9808 High Accuracy I2C Temperature Sensor Breakout
+* `Adafruit MCP9808 High Accuracy I2C Temperature Sensor Breakout
   <https://www.adafruit.com/products/1782>`_ (Product ID: 1782)
 
 **Software and Dependencies:**
 
 * Adafruit CircuitPython firmware for the supported boards:
   https://github.com/adafruit/circuitpython/releases
-* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
+
+* Adafruit's Bus Device library:
+  https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
+
+* Adafruit's Register library:
+  https://github.com/adafruit/Adafruit_CircuitPython_Register
+
 
 **Notes:**
 
 #.  Datasheet: http://www.adafruit.com/datasheets/MCP9808.pdf
 
 """
 
+from micropython import const
+from adafruit_bus_device.i2c_device import I2CDevice
+from adafruit_register.i2c_bits import RWBits
+from adafruit_register.i2c_bit import ROBit
+
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MCP9808.git"
 
-from adafruit_bus_device.i2c_device import I2CDevice
+
+_MCP9808_DEFAULT_ADDRESS = const(0x18)
+_MCP9808_DEVICE_ID = const(0x54)
+_MCP9808_REG_CONFIGURATION = const(0x01)
+_MCP9808_REG_UPPER_TEMP = const(0x02)
+_MCP9808_REG_LOWER_TEMP = const(0x03)
+_MCP9808_REG_CRITICAL_TEMP = const(0x04)
+_MCP9808_REG__TEMP = const(0x05)
+_MCP9808_REG_MANUFACTURER_ID = const(0x06)
+_MCP9808_REG_DEVICE_ID = const(0x07)
+_MCP9808_REG_RESOLUTION = const(0x08)
 
 # Resolution settings
-HALF_C = 0x0
-QUARTER_C = 0x1
-EIGHTH_C = 0x2
-SIXTEENTH_C = 0x3
+
+_MCP9808_RESOLUTION_HALF_C = const(0x0)
+_MCP9808_RESOLUTION_QUARTER_C = const(0x1)
+_MCP9808_RESOLUTION_EIGHTH_C = const(0x2)
+_MCP9808_RESOLUTION_SIXTEENTH_C = const(0x3)
 
 
 class MCP9808:
@@ -48,6 +70,17 @@ class MCP9808:
     :param ~busio.I2C i2c_bus: The I2C bus the MCP9808 is connected to.
     :param int address: The I2C address of the device. Defaults to :const:`0x18`
 
+    **MCP9808 Settings**
+        You could set the MCP9808 with different temperature limits and compare them with the
+        ambient temperature Ta
+
+        - above_ct this value will be set to `True` when Ta is above this limit
+        - above_ut: this value will be set to `True` when Ta is above this limit
+        - below_lt: this value will be set to `True` when Ta is below this limit
+
+        To get this value, you will need to read the temperature, and then access the attribute
+
+
     **Quickstart: Importing and using the MCP9808**
 
         Here is an example of using the :class:`MCP9808` class.
@@ -74,26 +107,33 @@ class MCP9808:
 
     """
 
-    # alert_lower_temperature_bound
-    # alert_upper_temperature_bound
-    # critical_temperature
-    # temperature
-    # temperature_resolution
+    _MCP9808_REG_RESOLUTION_SET = RWBits(2, 0x08, 0, register_width=2)
+    above_ct = ROBit(_MCP9808_REG__TEMP, 7, register_width=1)
+    """True when the temperature is above than the currently
+    set critical temperature. False Otherwise"""
+
+    above_ut = ROBit(_MCP9808_REG__TEMP, 6, register_width=1)
+    """True when the temperature is above than the currently
+    set high temperature. False Otherwise"""
 
-    def __init__(self, i2c_bus, address=0x18):
+    below_lt = ROBit(_MCP9808_REG__TEMP, 5, register_width=1)
+    """True when the temperature is below than the currently
+    set lower temperature. False Otherwise"""
+
+    def __init__(self, i2c_bus, address=_MCP9808_DEFAULT_ADDRESS):
         self.i2c_device = I2CDevice(i2c_bus, address)
 
         # Verify the manufacturer and device ids to ensure we are talking to
         # what we expect.
         self.buf = bytearray(3)
-        self.buf[0] = 0x06
+        self.buf[0] = _MCP9808_REG_MANUFACTURER_ID
         with self.i2c_device as i2c:
             i2c.write_then_readinto(self.buf, self.buf, out_end=1, in_start=1)
 
-        ok = self.buf[2] == 0x54 and self.buf[1] == 0
+        ok = self.buf[2] == _MCP9808_DEVICE_ID and self.buf[1] == 0
 
         # Check device id.
-        self.buf[0] = 0x07
+        self.buf[0] = _MCP9808_REG_DEVICE_ID
         with self.i2c_device as i2c:
             i2c.write_then_readinto(self.buf, self.buf, out_end=1, in_start=1)
 
@@ -105,13 +145,113 @@ def __init__(self, i2c_bus, address=0x18):
     @property
     def temperature(self):
         """Temperature in Celsius. Read-only."""
-        self.buf[0] = 0x05
+        self.buf[0] = _MCP9808_REG__TEMP
         with self.i2c_device as i2c:
             i2c.write_then_readinto(self.buf, self.buf, out_end=1, in_start=1)
 
+        return self._temp_conv()
+
+    def _temp_conv(self):
+        """Internal function to convert temperature given by the sensor"""
         # Clear flags from the value
         self.buf[1] = self.buf[1] & 0x1F
         if self.buf[1] & 0x10 == 0x10:
             self.buf[1] = self.buf[1] & 0x0F
             return (self.buf[1] * 16 + self.buf[2] / 16.0) - 256
         return self.buf[1] * 16 + self.buf[2] / 16.0
+
+    def _limit_temperatures(self, temp, t_address=0x02):
+        """Internal function to setup limit temperature
+
+        :param int temp: temperature limit
+        :param int t_address: register address for the temperature limit
+                                0x02 : Upper Limit
+                                0x03 : Lower Limit
+                                0x04 : Critical Limit
+        """
+
+        if temp < 0:
+            negative = True
+            temp = abs(temp)
+        else:
+            negative = False
+
+        self.buf[0] = t_address
+
+        self.buf[1] = temp >> 4
+        if negative:
+            self.buf[1] = self.buf[1] | 0x10
+
+        self.buf[2] = (temp & 0x0F) << 4
+
+        with self.i2c_device as i2c:
+            i2c.write(self.buf)
+
+    def _get_temperature(self, address):
+        self.buf[0] = address
+        with self.i2c_device as i2c:
+            i2c.write_then_readinto(self.buf, self.buf, out_end=1, in_start=1)
+
+        return self._temp_conv()
+
+    def _set_temperature(self, temp, address):
+        self._limit_temperatures(temp, address)
+
+    @property
+    def upper_temperature(self):
+        """Upper alarm temperature in Celsius"""
+
+        return self._get_temperature(_MCP9808_REG_UPPER_TEMP)
+
+    @upper_temperature.setter
+    def upper_temperature(self, temp):
+        """Setup Upper temperature"""
+
+        self._limit_temperatures(temp, _MCP9808_REG_UPPER_TEMP)
+
+    @property
+    def lower_temperature(self):
+        """Lower alarm temperature in Celsius"""
+
+        return self._get_temperature(_MCP9808_REG_LOWER_TEMP)
+
+    @lower_temperature.setter
+    def lower_temperature(self, temp):
+        """Setup Lower temperature"""
+
+        self._limit_temperatures(temp, _MCP9808_REG_LOWER_TEMP)
+
+    @property
+    def critical_temperature(self):
+        """Critical alarm temperature in Celsius"""
+
+        return self._get_temperature(_MCP9808_REG_CRITICAL_TEMP)
+
+    @critical_temperature.setter
+    def critical_temperature(self, temp):
+        """Setup Critical temperature"""
+
+        self._limit_temperatures(temp, _MCP9808_REG_CRITICAL_TEMP)
+
+    @property
+    def resolution(self):
+        """Temperature Resolution in Celsius
+
+        =======   ============   ==============
+         Value     Resolution     Reading Time
+        =======   ============   ==============
+          0          0.5°C            30 ms
+          1          0.25°C           65 ms
+          2         0.125°C          130 ms
+          3         0.0625°C         250 ms
+        =======   ============   ==============
+
+        """
+
+        return self._MCP9808_REG_RESOLUTION_SET
+
+    @resolution.setter
+    def resolution(self, resol_value=3):
+        """ Setup Critical temperature"""
+
+        self._MCP9808_REG_RESOLUTION_SET = resol_value  # pylint: disable=invalid-name

docs/conf.py

@@ -31,6 +31,10 @@
         "https://circuitpython.readthedocs.io/projects/busdevice/en/latest/",
         None,
     ),
+    "Register": (
+        "https://circuitpython.readthedocs.io/projects/register/en/latest/",
+        None,
+    ),
     "CircuitPython": ("https://circuitpython.readthedocs.io/en/latest/", None),
 }
 

docs/examples.rst

@@ -6,3 +6,13 @@ Ensure your device works with this simple test.
 .. literalinclude:: ../examples/mcp9808_simpletest.py
     :caption: examples/mcp9808_simpletest.py
     :linenos:
+
+
+Temperature Limit test
+----------------------
+
+Show the MCP9808 to setup different temperature values
+
+.. literalinclude:: ../examples/mcp9808_temperature_limits.py
+    :caption: examples/mcp9808_temperature_limits.py
+    :linenos:

examples/mcp9808_simpletest.py

@@ -14,7 +14,6 @@
 # Necessary when, for example, connecting A0 to VDD to make address=0x19
 # mcp = adafruit_mcp9808.MCP9808(i2c_bus, address=0x19)
 
-
 while True:
     tempC = mcp.temperature
     tempF = tempC * 9 / 5 + 32

examples/mcp9808_temperature_limits.py

@@ -0,0 +1,32 @@
+# SPDX-FileCopyrightText: 2021 Jose David M.
+# SPDX-License-Identifier: MIT
+
+"""
+Show the MCP9808 to setup different temperature values
+"""
+
+import time
+import board
+import adafruit_mcp9808
+
+i2c = board.I2C()  # uses board.SCL and board.SDA
+mcp = adafruit_mcp9808.MCP9808(i2c)
+
+# Change the values according to the desired values
+print("Setting Temperature Limits")
+mcp.upper_temperature = 23
+mcp.lower_temperature = 10
+mcp.critical_temperature = 100
+
+# To verify the limits we need to read the temperature value
+print(mcp.temperature)
+time.sleep(0.3)  # This is the time temperature conversion at maximum resolution
+
+# Showing temperature Limits
+while True:
+    if mcp.below_lt:
+        print("too cold!")
+    if mcp.above_ut:
+        print("getting hot!")
+    if mcp.above_ct:
+        print("Above critical temp!")

requirements.txt

@@ -2,4 +2,6 @@
 #
 # SPDX-License-Identifier: Unlicense
 
+Adafruit-Blinka
 adafruit-circuitpython-busdevice
+adafruit-circuitpython-register