Office Touch Panel

Parts List

• Arduino UNO R4 WiFi
• MCUFRIEND 2.4" TFT shield (resistive touch, ILI9341 or compatible)
• Reed switch (door sensor) — wired to SCL pin
• Physical momentary button — wired to D1 (TX) pin
• USB-C power supply or 5 V DC barrel jack
• Home Assistant instance with MQTT broker (e.g. Mosquitto add-on)
• 2.4 GHz Wi-Fi network
• Dupont jumper wires, enclosure of your choice

Wiring

The TFT shield slots directly onto the Arduino headers. The two external sensors connect to spare pins left exposed by the shield.

• Reed switch → one leg to SCL, other leg to GND uses INPUT_PULLUP
• Physical button → one leg to D1, other leg to GND uses INPUT_PULLUP
• TFT backlight → D7 (HIGH = on)
• TFT touch X+/X−/Y+/Y− → D9 / A3 / A2 / D8 (shield default)

Required Libraries

Install all of these through the Arduino IDE Library Manager (Tools → Manage Libraries):

• Riscduino_MCUFRIEND_kbv — TFT driver
• Adafruit GFX Library — graphics primitives
• TouchScreen — resistive touch decoding
• WiFiS3 — built-in, UNO R4 WiFi only
• ArduinoMqttClient — MQTT publish/subscribe

Home Assistant & MQTT Setup

1. Install & configure the Mosquitto MQTT broker

   In Home Assistant, go to Settings → Add-ons → Mosquitto broker and install it. Create an MQTT user under Settings → People (or use an existing HA user). Note the broker's local IP — you'll put it in the sketch.

2. MQTT topics used by this sketch

   All topics are prefixed with home/buttons/office/ or office/. The sketch publishes commands and subscribes to /state feedback so the display stays in sync if HA changes a device externally.

   MQTT topic map Copy

   # Published by Arduino (commands)
   home/buttons/office/light          → "ON" / "OFF"
   home/buttons/office/power          → "ON" / "OFF"
   home/buttons/office/3dprint        → "ON" / "OFF"
   home/buttons/office/tap            → "1" / "2" / "3" / "long"
   office/door/state                  → "open" / "closed"
   office/arduino/temperature         → "26.3"  (°C, float string)
   
   # Subscribed by Arduino (state feedback)
   home/buttons/office/light/state    → "ON" / "OFF"
   home/buttons/office/power/state    → "ON" / "OFF"
   home/buttons/office/3dprint/state  → "ON" / "OFF"
   
   # Auto-discovery (published once on boot, retained)
   homeassistant/binary_sensor/office_door/config
   homeassistant/sensor/office_arduino_temp/config

3. Create HA automations for each button

   In Home Assistant create an automation triggered by MQTT message on e.g. home/buttons/office/light. The action toggles your light switch entity, then publishes the new state back to home/buttons/office/light/state so the panel display updates.

   YAML — example HA automation (light button) Copy

   alias: "Office panel - light button"
   trigger:
     - platform: mqtt
       topic: home/buttons/office/light
   action:
     - service: >
         {% if trigger.payload == 'ON' %}
           light.turn_on
         {% else %}
           light.turn_off
         {% endif %}
       target:
         entity_id: light.office_main
     - service: mqtt.publish
       data:
         topic: home/buttons/office/light/state
         payload: "{{ trigger.payload }}"
         retain: false

Arduino Sketch

Download the sketch and edit the WiFi & MQTT CONFIG block near the top of the file before uploading. The sketch compiles on Arduino IDE 2.x with the UNO R4 WiFi board package installed.

What to edit before uploading

• WIFI_SSID — your 2.4 GHz network name
  WIFI_PASS — your Wi-Fi password
• MQTT_BROKER — local IP of your Home Assistant / Mosquitto host (e.g. 192.168.1.XX)
  MQTT_PORT — default 1883, change if you use a custom port
• MQTT_USER — MQTT broker username
  MQTT_PASS — MQTT broker password
• MQTT_LOCATION — short label used as the topic prefix (default "office"). All topics become home/buttons/office/… — change this if you deploy a second panel.
• MQTT_CLIENT_ID — unique ID for this device on the broker (default "arduino_r4_panel"). Must be unique if you run more than one panel.

How It Works

• Touch buttons (Light / Power / 3D Print)
  Tap to toggle — publishes ON or OFF to the matching MQTT topic. HA responds by publishing the new state back to /state, keeping the display in sync even if someone changes the device from a phone or voice assistant.
• Kill All / Start All button
  Shows red Kill All if any device is on — one tap turns everything off. Shows green Start All if everything is off — one tap turns everything on.
• Physical button — multi-tap & long press
  Publishes "1", "2", "3" (taps within 500 ms window) or "long" (held ≥ 1.5 s) to home/buttons/office/tap. Wire up HA automations however you like — e.g. double-tap = all lights off.
• Reed switch door sensor
  Publishes "open" / "closed" retained to office/door/state on every state change. Shows in the status bar at the bottom of the screen.
• Internal temperature sensor
  Reads the RA4M1 MCU's onboard ADC every 2 seconds, displays it on-screen in cyan, and publishes to MQTT so Home Assistant can graph it as a sensor entity. Auto-discovery config is sent on boot.
• Auto-reconnect
  Wi-Fi checked every 30 s, MQTT every 5 s. The status bar shows OK / NO for both so you can see at a glance if something has dropped.

Notes & Gotchas

• The TFT shield occupies most of the UNO's pins. D1 (TX) is used for the physical button — disconnect it before uploading or you'll get garbage data on the serial line.
• The temperature reading is an approximation using the ADC on A0 as a baseline. The RA4M1 doesn't expose the internal temp sensor directly via standard Arduino APIs yet — treat the values as indicative, not precise.
• Touch calibration constants (TS_MINX etc.) may need tweaking for your specific shield. Print raw ts.getPoint() values to Serial to calibrate.
• The sketch uses INPUT_PULLUP on both the button and reed switch — so both are active-low (connect to GND, not 3.3 V).