The therminator project is a client/server application I'm developing to log data about my home. See therminator_server for the server component.
This repository houses the client component. The therminator module interfaces with a therminator device attached to a Raspberry Pi to measure temperature, humidity, and ambient light levels. The measurements are logged and sent to the therminator server API.
The therminator device includes a temperature sensor and a photoresistor. If using a DHT22 temperature sensor, the temperature and humidity will be measured. If a DS18B20 is used, only the temperature will be measured.
I'm still fleshing out this process.
The client depends on RPi.GPIO, Adafruit_DHT, PyYAML, and requests.
$ python3 -m therminator -h
usage: __main__.py [-h] -c FILE [-d] [-v]
optional arguments:
-h, --help show this help message and exit
-c FILE, --config FILE
Path to YAML config file
-d, --debug Enable debugging output
-v, --version Display version information and exit
$ python3 -m therminator --config path/to/config.ymlThe details of how the device is wired up to the Raspberry Pi should be placed
in a YAML file and passed to the client with the --config option. See the
file sample_config.yml for an example configuration.
In order to read from a DHT22 sensor, the Adafruit_DHT22 needs to be installed on the Raspberry Pi, and the config file should provide the GPIO pin to which the DHT22's data pin as connected.
Adafruit has a great tutorial on working with DHTxx sensors. The expected circuit design and code for interfacing with it is derived from this tutorial.
In order to read from a DS18B20 sensor, 1-wire support needs to into the
kernel. This can be enabled by running raspi-config or by adding the
following line to /boot/config.txt:
dtoverlay=w1-gpio
In addition, the w1_therm kernel module needs to be loaded. (I am new to
Raspberry Pis. In practice, this module just seems to be available once 1-wire
is enabled and a DS18B20 is attached. I may be forgetting something.)
Adafruit also has a great tutorial for working with the DS18B20 from a Raspberry Pi.
The photoresistor is used by measuring the amount of time it takes to charge a capacitor through the photoresistor. The config file should provide the capacticance of the capacitor (in μF), the resistance of the regular resistor through which current is flowing (in Ω), and the GPIO pins used to charge and discharge the capacitor.
Multiple measurements of the resistance of the photoresistor will be taken, and the average of those readings will be returned. By default, 20 readings and taken. In extremely dark conditions, this may take a very long time. It may be necessary to use a smaller capacitor or take fewer readings if you are unable to get a reading within a reasonable amount of time. (By default, the client will timeout if it hasn't completed 20 readings within 5 minutes.)
The expected design of this portion of the circuit and the code for working with it is derived from the "Analog Inputs" section of "Chapter 9: Interfacing Hardware" of Programming the Raspberry Pi (2nd Ed.).