Raspberry Pi SenseHat + pywws

Read Temperature/Pressure/Humidity from a Raspberry Pi SenseHat

Write the data to a pywws DataStore

Process the data with pywws...

Read the forecast back from pywws

Read the forecast from Australia's BoM

Output to MQTT (Useful for things like OpenHAB integration)

Output to a local LCD display

Warning

I've stopped work on the PiSense parts of this project, as the readings I'm getting from the SenseHat seem way out. The Temperature inputs are impacted significantly by heat coming from the Raspberry Pi. Double-stacking the headers, using a heat-shield, turning off the display, moving USB wifi away on a cable... none of them work. Relative Humidity is also very bad - 69% when it's raining?! (Government weather station just down the road said > 90%)

Sensors

• Raspberry Pi SenseHat - not recommended
• Adafruit BME280 - Temperature, Pressure, Humidity
• Adafruit SI1145 - Light, UV
• Adafruit BMP085 - Temperature, Pressure (Discontinued - replaced by BMP180)
• Adafruit BMP180 Should work - Temperature, Pressure
• EnOcean - Only Temperature sensors are decoded at the moment.

Displays

• Adafruit 16x2 RGB LCD Display Positive and Negative (on an Adafruit Pi Plate - providing an i2c interface)
• Raspberry Pi SenseHat

Reading data

Use weather_event.py - multi-threaded, better timing, recommended

Timing

weather_event.py uses APScheduler to handle threading and timing. Each section of code runs on a separate timer/thread:

• Sample: Read SenseHat, send to a smoothing function
• Store: Send data to pywws's DataStore
• Flush: Tell pywws's DataStore to write to disk
• ForecastRefresh: Grab the latest forecast from pywws, for display on the Hat
• WriteConsole: Output Temperature/Pressure/Humidity to stdout/console
• WriteSenseHat: Output Temperature/Pressure/Humidity to the Hat

Configuration

All the configuration is in the PiWeather.ini file. A sample called PiWeather.ini-example is included. Copy and edit as appropriate. Configuration is reloaded on a timer (See the Rates section of the config file)

Look at the Rates section for timing (in seconds)

SMOOTHING defines the size of the sliding window - used to average out readings

Sense Hat

ROTATION defines which way the SenseHat is siting. GPIO pins in top left corner == 0, USB ports top == 90 et cetera

Daytime is considered any hour between DAWN and DUSK, outside this period the ..._NIGHT values are used for the SenseHat display.

A comfortable temperature is considered any temp_in (Indoors) temperature between COMFORT_LOW and COMFORT_HIGH, and thus corresponds to a SenseHat background of COLOUR_MID, COLOUR_COLD and COLOUR_HOT are used either side of this comfort zone.

Note: SCROLL (scroll rate) - higher values == slower

EnOcean

Channel names for recording the data (e.g. for pushing to MQTT) are stored in the configuration file. Each sensor has an entry with its hexadecimal address and a name. e.g. 01812345 = room1, would mean an sensor with address 01:81:23:45 would be stored as room1

BoM

Find your state here, it will look something like IDV10753 Have a look inside the XML, and find your nearest BoM forecast area, it will look something like VIC_PT042

Homie

Listens for incoming MQTT messages, and maps to local sensor variables, that can then be displayed. Original intent was to utilise a python Homie library, however I failed to find one that could listen, instead of publish. Current implementation subscribes to a number of Topics, and then maps a device to a local variable.