docs(MMM-SenseHat): add module screenshot

Author: EmanuelVasileGresnu

modules/MMM-SenseHat/README.md

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+MMM-SenseHat
+============
+
+A 3rd‑party MagicMirror² module that integrates the Raspberry Pi Sense HAT. It reads sensor data (temperature, humidity, pressure, optional orientation) and can control the Sense HAT 8×8 RGB LED matrix for simple status indication or scrolling text.
+
+## Screenshot
+![MMM-SenseHat screenshot](images/how_its_working.png)
+
+Features
+- Display temperature, humidity, pressure, and optionally orientation (pitch/roll/yaw)
+- Periodic polling interval (configurable)
+- Optional LED matrix control: off, status color, or scrolling text
+- Basic threshold‑based LED status (green when normal, red when out‑of‑range)
+
+Requirements
+- Raspberry Pi with a Sense HAT attached
+- Python 3 with the official sense HAT library
+
+Install dependencies on the Raspberry Pi
+```bash
+sudo apt update
+sudo apt install -y sense-hat python3-sense-hat
+```
+
+Installation (as a 3rd‑party module)
+1) Clone this module into your MagicMirror installation under `modules/MMM-SenseHat`:
+```bash
+cd ~/MagicMirror/modules
+git clone https://github.com/YOUR_GITHUB_ACCOUNT/MMM-SenseHat.git MMM-SenseHat
+```
+
+2) (Optional) Ensure the Python helper is executable:
+```bash
+chmod +x ~/MagicMirror/modules/MMM-SenseHat/python/reader.py
+```
+
+Configuration
+Add the module to your `config/config.js`:
+```js
+{
+  module: "MMM-SenseHat",
+  position: "top_right",
+  config: {
+    updateInterval: 5000,
+    showTemperature: true,
+    showHumidity: true,
+    showPressure: true,
+    showOrientation: false,
+    temperatureUnit: "C",
+    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 if needed (e.g., "/usr/bin/python3")
+    // pythonPath: "/usr/bin/python3"
+  }
+}
+```
+
+How it works
+- Frontend (MMM-SenseHat.js): Displays data and optionally sends LED status commands based on thresholds.
+- Node Helper (node_helper.js): Spawns the Python helper to read sensors at a set interval and forwards LED commands to it. Respects `config.pythonPath` if provided.
+- Python Helper (python/reader.py): Uses `from sense_hat import SenseHat` to read sensors and control the LED matrix. Prints JSON to stdout in read mode.
+
+Troubleshooting
+1) Check that the Sense HAT is detected by the kernel
+```bash
+ls -l /dev/i2c*
+dmesg | grep -i "sense"
+```
+Expect:
+- `/dev/i2c-1` present
+- A line similar to: `fb1: RPi-Sense FB frame buffer device`
+- A joystick device entry for the Sense HAT
+
+2) Probe I²C bus 1
+```bash
+sudo i2cdetect -y 1
+```
+On a working Sense HAT, you should see several non-"--" addresses (for example `1c`, `39`, `5c`, `5f`, `6a`). If everything shows `--`, the HAT might not be seated correctly or could be faulty.
+
+3) Test using the official Python library
+```bash
+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 errors like `OSError: Humidity Init Failed`, there may be a contact problem on the header or a sensor issue.
+
+4) Check the LED matrix
+```bash
+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 you don’t see LEDs:
+- 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 (library missing, init failure, etc.).
+
+License
+MIT (follow the MagicMirror² project license)