MMM-SenseHat

Overview

MMM-SenseHat is a third-party module for MagicMirror² that integrates the official Raspberry Pi Sense HAT. It displays sensor readings (temperature, humidity, pressure, and optional orientation) and can control the Sense HAT’s 8×8 RGB LED matrix for a status color or scrolling text.

• Sense HAT product page: https://www.raspberrypi.com/products/sense-hat/
• Sense HAT documentation: https://www.raspberrypi.com/documentation/accessories/sense-hat.html

This is not a core/default MagicMirror module. Install it under: modules/MMM-SenseHat.

Features

• Show temperature, humidity, and pressure
• Optional orientation readout (pitch / roll / yaw)
• Configurable polling interval
• LED matrix control: off, status color, or scrolling text
• Basic threshold-based LED status (green when normal, red when out of range)
• Runs as a standard MagicMirror third-party module (folder: modules/MMM-SenseHat)

Requirements

• Raspberry Pi with a Sense HAT attached
• MagicMirror² installed and running
• Python 3 with the official Sense HAT library

Install dependencies on the Raspberry Pi:

sudo apt update
sudo apt install -y sense-hat python3-sense-hat

Installation

Clone this repository into your MagicMirror installation under modules/MMM-SenseHat.

cd ~/MagicMirror/modules
git clone https://github.com/YOUR_GITHUB_ACCOUNT/MMM-SenseHat.git MMM-SenseHat

Optional: ensure the Python helper is executable:

chmod +x ~/MagicMirror/modules/MMM-SenseHat/python/reader.py

Configuration

Add the module to your config/config.js following standard MagicMirror style. Paste the following object into the modules: [] array:

const moduleEntry = {
  module: "MMM-SenseHat",
  position: "top_right",
  config: {
    updateInterval: 5000,
    showTemperature: true,
    showHumidity: true,
    showPressure: true,
    showOrientation: false,
    temperatureUnit: "C", // "C" or "F"
    roundValues: 1,
    ledMatrixEnabled: true,
    ledMode: "status", // "off" | "status" | "text"
    ledText: "Hello from Sense HAT",
    ledColor: [0, 255, 0],
    criticalThresholds: {
      temperatureHigh: 30,
      temperatureLow: 10,
      humidityHigh: 80,
      humidityLow: 20
    },
    debug: false,
    // Optional: override Python executable path (e.g., "/usr/bin/python3").
    // For familiarity with MMM-PythonPrint, you can also use `pythonName` (alias of pythonPath).
    // pythonPath: "/usr/bin/python3",
    // pythonName: "/usr/bin/python3"
  }
};
// Then insert `moduleEntry` into the modules array in your config.js

How it works (architecture)

• Frontend (MMM-SenseHat.js)
  • Renders the sensor values in the MagicMirror UI
  • Shows clear states: loading, error, or data
  • May send LED commands (status/text) back to the backend based on thresholds
• Node helper (node_helper.js)
  • Manages one polling loop per module instance (multi-instance safe)
  • Spawns the Python helper on an interval to read sensors
  • Forwards sensor JSON to the correct frontend instance via an identifier
  • Accepts LED commands per instance and uses that instance’s config
  • Respects config.pythonPath (or pythonName) to select the Python executable
• Python helper (python/reader.py)
  • Uses from sense_hat import SenseHat
  • Reads sensors and prints JSON to stdout in --read mode
  • Controls the LED matrix (status color, text, clear)

Troubleshooting

1. Check that the Sense HAT is detected by the kernel

ls -l /dev/i2c*
dmesg | grep -i "sense"

Expected:

• /dev/i2c-1 present
• A line like fb1: RPi-Sense FB frame buffer device
• A Sense HAT joystick device entry

2. Probe I²C bus 1

sudo i2cdetect -y 1

On a working Sense HAT, you should see several non-"--" addresses (e.g., 1c, 39, 5c, 5f, 6a). If everything shows --, the HAT may not be seated correctly or could be faulty.

3. Test using the official Python library

python3 - << 'PY'
from sense_hat import SenseHat

sh = SenseHat()

print("Temperature:", sh.get_temperature())
print("Humidity   :", sh.get_humidity())
print("Pressure   :", sh.get_pressure())
PY

• If you get numeric values, the sensors are working.
• If you see OSError: Humidity Init Failed, check the 40-pin header seating and try again.

4. Check the LED matrix

python3 - << 'PY'
from sense_hat import SenseHat
from time import sleep

sh = SenseHat()
sh.clear()
sh.show_message("HI", text_colour=(0, 255, 0), scroll_speed=0.07)
sleep(1)
sh.clear()
PY

If no LEDs appear:

• Power off the Raspberry Pi
• Firmly press the Sense HAT onto the 40-pin header (common on new boards)
• Boot again and re-run the test

5. What the MagicMirror module will show

• "Loading Sense HAT data…" → Python helper hasn’t delivered any data yet
• "Sense HAT: no sensor data (check hardware or drivers)" → helper runs, but all sensor fields are null
• "Sense HAT error: …" → helper reported an explicit error (e.g., library missing, init failure). Errors are per instance.

Multiple instances

You can place MMM-SenseHat in modules:[] multiple times, each with different options (e.g., different LED policies or intervals). The module tags all traffic with an identifier and the helper maintains one polling loop per instance, so configurations are isolated.

Example with two instances (as part of your modules array):

[
  {
    module: "MMM-SenseHat",
    position: "top_right",
    config: { updateInterval: 4000, ledMatrixEnabled: true, ledMode: "status" }
  },
  {
    module: "MMM-SenseHat",
    position: "bottom_right",
    config: { updateInterval: 10000, ledMatrixEnabled: true, ledMode: "text", ledText: "Hello", ledColor: [0, 200, 255] }
  }
]

Screenshots

• images/mmm-sensehat-dashboard.png — UI screenshot of the module
• images/mmm-sensehat-hardware_1.jpg — Raspberry Pi + Sense HAT setup
• images/mmm-sensehat-hardware_2.jpg — Additional hardware photo

Styling: the module wraps its DOM in a div.mmm-sensehat, so you can target .MMM-SenseHat .mmm-sensehat from your custom.css if desired.

License

MIT — typical for MagicMirror third-party modules.