Supported Targets	ESP32-C3

Little Dawn - ESP32 ISOBUS Bridge

Little Dawn is an ESP32-based ISOBUS bridge that enables communication between agricultural equipment using the ISO 11783 (ISOBUS) protocol. It acts as a bridge between "New Dawn" (a proprietary agricultural device) and ISOBUS Virtual Terminals (VT), providing real-time display of machine data on standard agricultural displays.

Features

• Real-time Data Display: Shows wheel angle sensor (WAS) data and vehicle speed on ISOBUS VT displays
• High-Speed Serial Communication: 460800 baud serial link to New Dawn device
• CAN Bus Communication: Full ISO 11783 compliance at 250kbps
• Low Latency: Minimal lag (~50-100ms) between data updates
• Button Support: Soft key functionality for user interaction

Hardware Requirements

• MCU: ESP32-C3 (XIAO ESP32C3 in AiO board socket)
• CAN Transceiver: SN65HVD230
• Pin Configuration:
  • TWAI TX: GPIO4 (D2)
  • TWAI RX: GPIO5 (D3)
  • Status LED: GPIO8 (D8)
  • Serial to New Dawn: GPIO21/20 (D6/D7)

Software Architecture

The project uses:

• ESP-IDF v5.5: Espressif's official development framework
• AgIsoStack++: Open-source ISOBUS protocol stack
• Custom Components:
  • VT object pool display (LD13.iop)
  • Serial protocol handler for New Dawn communication
  • ESP32-specific logger integration

Building and Flashing

Option 1: Using ESP-IDF (for development)

1. Set up ESP-IDF environment:

source /path/to/esp-idf/export.sh

2. Build the project:

idf.py build

3. Flash and monitor:

idf.py -p /dev/cu.usbmodem* flash monitor

Option 2: Using pre-built binaries (no ESP-IDF required)

If you have pre-built binaries from the build directory, you can flash them directly using esptool.py:

esptool.py -p /dev/cu.usbmodem* -b 460800 --chip esp32c3 write_flash \
  --flash_mode dio --flash_freq 80m --flash_size 2MB \
  0x0 bootloader/bootloader.bin \
  0x8000 partition_table/partition-table.bin \
  0x10000 Little_Dawn.bin

Required files (found in the build directory after compilation):

• bootloader/bootloader.bin - Bootloader (flashed at 0x0)
• partition_table/partition-table.bin - Partition table (flashed at 0x8000)
• Little_Dawn.bin - Main application (flashed at 0x10000)

Serial Protocol

Communication with New Dawn uses a binary protocol:

• Format: [ID][LENGTH][DATA...][CHECKSUM]
• Machine Status Message (0x01) contains:
  • Speed (0.01 km/h units)
  • Heading (0.1 degree units)
  • Roll/Pitch (0.1 degree units)
  • Steering angle (0.1 degree units)

Project Status

The project is fully functional with:

• ✅ Bidirectional CAN communication
• ✅ ISOBUS address claiming
• ✅ VT object pool display
• ✅ Real-time data updates
• ✅ Serial communication with New Dawn

Configuration

Key settings in sdkconfig:

• ISOBUS threading disabled for manual update control
• TWAI (CAN) configured for 250kbps
• Custom partition table for larger application size

Troubleshooting

• No CAN communication: Check TWAI pin connections and transceiver power
• VT not displaying: Verify object pool format and VT compatibility
• Serial data issues: Confirm baud rate (460800) and checksum calculation

Technical Support

For issues or questions:

• Review the CLAUDE.md file for detailed technical notes
• Check debug logs with monitor command
• Use a CAN analyzer to verify message transmission

License

This project uses open-source components including AgIsoStack++ under their respective licenses.