Adding sensor interface and LM75 i2c sensor support

.gitignore

@@ -90,3 +90,6 @@ ENV/
 
 # Rope project settings
 .ropeproject
+
+#Kate
+*.kate-swp

README.md

@@ -1,15 +1,20 @@
 PI MQTT GPIO
 ============
 
-Expose the Raspberry Pi GPIO pins and/or external IO modules to an MQTT server. This allows pins to be read and switched by reading or writing messages to MQTT topics.
+Expose the Raspberry Pi GPIO pins, external IO modules and I2C sensors to an MQTT server. This allows pins to be read and switched by reading or writing messages to MQTT topics. The I2C sensors will be read periodically and publish their values. 
 
-Modules
--------
+GPIO Modules
+------------
 
 - Raspberry Pi GPIO (`raspberrypi`)
 - PCF8574 IO chip (`pcf8574`)
 - PiFaceDigital 2 IO board (`piface2`)
 
+I2C Sensors
+-----------
+
+- LM75 i2c temperature sensor (`lm75`)
+
 Installation
 ------------
 
@@ -82,6 +87,32 @@ digital_inputs:
     pulldown: no
 ```
 
+### Sensors
+
+Receive updates on the value of a sensor by subscribing to the `home/sensor/temperature` topic:
+
+```yaml
+mqtt:
+  host: test.mosquitto.org
+  port: 1883
+  user: ""
+  password: ""
+  topic_prefix: home
+
+sensor_modules:
+  - name: lm75
+    module: lm75
+    i2c_bus_num: 1
+    chip_addr: 0x48
+    cleanup: no  # This optional boolean value sets whether the module's `cleanup()` function will be called when the software exits.
+
+sensor_inputs:
+  - name: temperature
+    module: lm75
+    interval: 15 #interval in seconds, that a value is read from the sensor and a update is published
+    digits: 4 # number of digits to be round
+```
+
 #### SSL/TLS
 
 You may want to connect to a remote server, in which case it's a good idea to use an encrypted connection. If the server supports this, then you can supply the relevant config values for the [tls_set()](https://github.com/eclipse/paho.mqtt.python#tls_set) command.

config.example.yml

@@ -18,6 +18,12 @@ gpio_modules:
     module: stdio
     cleanup: no
 
+sensor_modules:
+  - name: lm75
+    module: lm75
+    i2c_bus_num: 1
+    chip_addr: 0x48
+
 digital_inputs:
   - name: button
     module: raspberrypi
@@ -30,7 +36,7 @@ digital_inputs:
 digital_outputs:
   - name: bell
     module: pcf8574
-    pin: 20
+    pin: 5
     on_payload: "ON"
     off_payload: "OFF"
     initial: low
@@ -40,3 +46,10 @@ digital_outputs:
     pin: 1
     on_payload: "ON"
     off_payload: "OFF"
+
+sensor_inputs:
+  - name: temperature
+    module: lm75
+    interval: 15
+    digits: 4
+

config.schema.yml

@@ -92,7 +92,29 @@ mqtt:
 
 gpio_modules:
   type: list
-  required: yes
+  required: no
+  default: []
+  schema:
+    type: dict
+    allow_unknown: yes
+    schema:
+      name:
+        type: string
+        required: yes
+        empty: no
+      module:
+        type: string
+        required: yes
+        empty: no
+      cleanup:
+        type: boolean
+        required: no
+        default: yes
+
+sensor_modules:
+  type: list
+  required: no
+  default: []
   schema:
     type: dict
     allow_unknown: yes
@@ -189,3 +211,33 @@ digital_outputs:
         type: boolean
         required: no
         default: no
+
+sensor_inputs:
+  type: list
+  required: no
+  default: []
+  schema:
+    type: dict
+    schema:
+      name:
+        type: string
+        required: yes
+        empty: no
+      module:
+        type: string
+        required: yes
+        empty: no
+      retain:
+        type: boolean
+        required: no
+        default: no
+      interval:
+        type: integer
+        required: no
+        default: 60
+        min: 1
+      digits:
+        type: integer
+        required: no
+        default: 2
+        min: 0

pi_mqtt_gpio/__init__.py

@@ -95,7 +95,29 @@
 
 gpio_modules:
   type: list
-  required: yes
+  required: no
+  default: []
+  schema:
+    type: dict
+    allow_unknown: yes
+    schema:
+      name:
+        type: string
+        required: yes
+        empty: no
+      module:
+        type: string
+        required: yes
+        empty: no
+      cleanup:
+        type: boolean
+        required: no
+        default: yes
+
+sensor_modules:
+  type: list
+  required: no
+  default: []
   schema:
     type: dict
     allow_unknown: yes
@@ -193,4 +215,34 @@
         required: no
         default: no
 
+sensor_inputs:
+  type: list
+  required: no
+  default: []
+  schema:
+    type: dict
+    schema:
+      name:
+        type: string
+        required: yes
+        empty: no
+      module:
+        type: string
+        required: yes
+        empty: no
+      retain:
+        type: boolean
+        required: no
+        default: no
+      interval:
+        type: integer
+        required: no
+        default: 60
+        min: 1
+      digits:
+        type: integer
+        required: no
+        default: 2
+        min: 0
+
 """)

pi_mqtt_gpio/modules/__init__.py

@@ -55,3 +55,25 @@ def cleanup(self):
         Called when closing the program to handle any cleanup operations.
         """
         pass
+
+
+class GenericSensor(object):
+    """
+    Abstracts a generic sensor interface to be implemented
+    by the modules in this directory.
+    """
+    __metaclass__ = abc.ABCMeta
+
+    @abc.abstractmethod
+    def setup_sensor(self, config):
+        pass
+
+    @abc.abstractmethod
+    def get_value(self, sensor):
+        pass
+
+    def cleanup(self):
+        """
+        Called when closing the program to handle any cleanup operations.
+        """
+        pass

pi_mqtt_gpio/modules/lm75.py

@@ -0,0 +1,41 @@
+from pi_mqtt_gpio.modules import GenericSensor
+
+
+"""REQUIREMENTS = ("smbus",)"""
+CONFIG_SCHEMA = {
+    "i2c_bus_num": {
+        "type": "integer",
+        "required": True,
+        "empty": False
+    },
+    "chip_addr": {
+        "type": "integer",
+        "required": True,
+        "empty": False
+    }
+}
+
+LM75_TEMP_REGISTER = 0
+
+
+class Sensor(GenericSensor):
+    """
+    Implementation of Sensor class for the LM75 temperature sensor.
+    """
+    def __init__(self, config):
+        import smbus
+        self.bus = smbus.SMBus(config["i2c_bus_num"])
+        self.address = config["chip_addr"]
+
+    def setup_sensor(self, config):
+        return True  # nothing to do here
+
+    def get_value(self, sensor):
+        """get the temperature value from the sensor"""
+        value = self.bus.read_word_data(self.address,
+                                        LM75_TEMP_REGISTER) & 0xFFFF
+        value = ((value << 8) & 0xFF00) + (value >> 8)
+        return self.convert_to_celsius(value)
+
+    def convert_to_celsius(self, value):
+        return (value / 32.0) / 8.0