VESC CAN Frame Builder

Notes

Extended ID Format: (CAN_PACKET_ID << 8) | ControllerID

Data encoding: Follows firmware buffer scales (see comm_can.c)

RX Buffer Multi-frame: FILL_RX_BUFFER commands split large payloads across multiple frames. Use PROCESS_RX_BUFFER to execute the assembled command with CRC validation.

UART Command Builder

The new UART Command Builder allows you to send any COMM_PACKET_ID command over CAN using the RX buffer protocol. This enables complex operations like configuration changes, motor detection, and terminal commands.

How it works:

1. Select a UART command (e.g., COMM_GET_VALUES, COMM_SET_DUTY)
2. Fill in the command-specific parameters (automatically generated UI)
3. The tool builds a complete UART packet with proper payload encoding and CRC16
4. Generates the CAN frame sequence to send it via RX buffer

Automatic Buffer Optimization:

• PROCESS_SHORT_BUFFER: Single CAN frame for commands ≤6 bytes (auto-selected)
• FILL_RX_BUFFER + PROCESS_RX_BUFFER: Multi-frame sequence for larger commands
• Smart Selection: Tool automatically chooses the most efficient transmission method

Example Usage:

• Get Values: Select COMM_GET_VALUES (no parameters needed) → Request motor data
• Set Current: Select COMM_SET_CURRENT, enter "10.0" in Current field → Set 10A current
• Terminal Command: Select COMM_TERMINAL_CMD, enter "help" → Send terminal command
• Motor Detection: Select COMM_DETECT_MOTOR_PARAM, set max power loss → Start detection

Response Modes (commands_send parameter):

• Mode 0: Packet goes to commands_process_packet of receiver (normal processing + response)
• Mode 1: Packet goes to commands_send_packet of receiver (direct send without processing)
• Mode 2: Packet goes to commands_process and send function is set to null so that no reply is sent back
• Mode 3: Same as 0, but the reply is processed locally and not sent out on the last interface

Smart Parameter Generation:

• Automatically creates appropriate input fields for each command
• Handles proper data scaling (duty×1e5, current×1e3, position×1e6, etc.)
• Provides helpful descriptions and valid ranges for each parameter
• Supports floats, integers, strings, and binary data as needed

Traditional RX Buffer sequence:

1. FILL_RX_BUFFER (offset=0, data=first chunk)
2. FILL_RX_BUFFER (offset=7, data=second chunk)
3. PROCESS_RX_BUFFER (lastID, cmdSend, totalLen, CRC16)