TrailCurrent Wall Mounted Display

Central control display firmware for an ESP32-P4 with a 7" touchscreen, providing a dashboard for monitoring and controlling devices on the TrailCurrent CAN bus via WiFi and MQTT.

Home Screen

Hardware Overview

• Microcontroller: ESP32-P4 (Waveshare ESP32-P4 WiFi6 Touch LCD 7B) — selected for its processing power and rich display capability, enabling more engaging touch-panel UIs
• WiFi: Via ESP-Hosted (ESP32-C6 slave over SDIO)
• Display: 7" 1024x600 MIPI-DSI LCD with capacitive touch
• Build System: ESP-IDF v5.5.2
• SD Card: SDMMC 4-bit mode for configuration (separate bus from ESP-Hosted SDIO)
• Key Features:
  • Central dashboard for trailer system monitoring
  • Thermostat with temperature control
  • Eight device control buttons
  • SD card provisioning: insert a config.env to configure WiFi and MQTT credentials, stored to NVS for ongoing use
  • MQTT over TLS (mqtts://) for real-time data from the TrailCurrent platform
  • Light control with on/off and brightness via MQTT
  • GPS, energy, and air quality monitoring via MQTT subscriptions
  • Color theme switching
  • Screen brightness and timeout controls
  • Timezone selection
  • NVS-persisted user settings (theme, brightness, timeout, timezone)
  • LVGL v8 UI designed with EEZ Studio
  • FreeCAD enclosure design

Hardware Requirements

Components

• Board: Waveshare ESP32-P4 WiFi6 Touch LCD 7B
• WiFi Module: ESP32-C6 (integrated, communicates via ESP-Hosted SDIO)

Firmware

This project uses ESP-IDF (not PlatformIO).

Setup:

# Install ESP-IDF v5.5.2 (if not already installed)
# See https://docs.espressif.com/projects/esp-idf/en/stable/esp32p4/get-started/

# Set target
idf.py set-target esp32p4

# Configure (optional - sdkconfig.defaults has working defaults)
idf.py menuconfig

# Build
idf.py build

# Flash
idf.py -p /dev/ttyUSBx flash

# Monitor serial output
idf.py -p /dev/ttyUSBx monitor

Firmware Dependencies

Dependencies are managed by the ESP-IDF component manager and resolved automatically during build:

• LVGL (v8.4.x) - Light and Versatile Graphics Library
• esp_wifi_remote - WiFi via ESP-Hosted
• esp_hosted - ESP32-C6 slave communication

SD Card Configuration

WiFi and MQTT settings are provisioned via an SD card. Create a config.env file on a FAT-formatted SD card:

WIFI_SSID=YourNetworkName
WIFI_PWD=YourWiFiPassword
MQTT_HOST=192.168.1.100
MQTT_PORT=8883
MQTT_USER=mqttuser
MQTT_PASS=mqttpassword

Optionally include a ca.crt file on the SD card for custom TLS certificate authority.

On boot, the device reads config.env from the SD card and stores the values into NVS. Once provisioned, the SD card is not needed for normal operation — it only needs to be reinserted to update settings. The device uses the same config.env format as the TrailCurrent Waveshare ESP32-S3 Remote.

MQTT

The MQTT client connects over TLS (mqtts://) using credentials from NVS. It subscribes to:

• local/lights/+/status — Light on/off and brightness state
• local/energy/status — Energy monitoring data
• local/airquality/temphumid — Temperature and humidity
• local/gps/latlon, local/gps/alt, local/gps/details — GPS data

Light commands are published to local/lights/{id}/command.

Project Structure

├── ASSETS/                       # UI design assets (images, SVGs)
├── CAD/                          # FreeCAD enclosure design and STL exports
├── DOCS/                         # Documentation and screenshots
│   └── IMAGES/                   # UI screenshots
├── GUI/                          # EEZ Studio UI design files
├── components/                   # Custom ESP-IDF components
│   ├── bsp_extra/                # Board support package extensions
│   ├── mqtt_client/              # MQTT client with TLS, NVS settings, subscriptions, JSON processing
│   └── sd_config/                # SD card config.env reader, stores to NVS
├── main/                         # Main application source
│   ├── main.c                    # Boot sequence, WiFi connect, MQTT init
│   ├── actions.c                 # UI action callbacks (light control, settings, themes)
│   ├── vars.c                    # UI variable bindings and LVGL widget updates
│   ├── mqtt_vars.h               # Declarations for MQTT-sourced variables
│   ├── idf_component.yml         # Component dependencies
│   └── ui/                       # EEZ Studio generated UI code (do not edit)
├── CMakeLists.txt                # Top-level CMake configuration
├── sdkconfig.defaults            # ESP-IDF configuration defaults
├── partitions.csv                # Flash partition layout (26MB app + 5MB storage)
└── LICENSE                       # MIT License

License

MIT License - See LICENSE file for details.

Contributing

Improvements and contributions are welcome! Please submit issues or pull requests.