node-red-contrib-seeed-recamera/nodes/can_to_angle.html

Node-RED nodes for reCamera

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            <span>Output as <b>motor angle</b></span>
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<script type="text/markdown" data-help-name="can-to-angle">
# CAN to angle

This node decodes and converts the raw data read from CANbus to decimal angular values.

## Overview
The node takes a CAN message object as input and extracts the motor ID, command type, and angle/offset value. It supports absolute position commands (A4), relative offset commands (A8), and status query commands (94).

## Input Configuration
The Input field allows you to specify the message property, flow context, or global context variable that contains the CAN message object. By default, it uses `msg.payload`.

## Input Format
The input should be a CAN message object with the following structure:
```json
{
  "id": 0x141,  // Motor ID in hex format (0x141 for Yaw, 0x142 for Pitch)
  "data": [...]  // Byte array containing the command data (8 bytes)
}
```

Example:
```json
{
  "id": 0x141,
  "data": [0xA4, 0x00, 0x5A, 0x00, 0x10, 0x27, 0x00, 0x00]
}
```

## Command Validation
The node includes advanced validation to ensure only meaningful data commands are processed:

- **94 commands**: Must NOT have all remaining bytes as zero (which would indicate a query, not a response)
- **A4/A6 commands**: The second byte must be 0x00 or 0x01 to be considered valid (excludes ACK responses like 0x2F)
- **A8 commands**: The second byte must be 0x00 to be considered valid

These validation rules prevent processing ACK responses and query commands that would result in incorrect angle calculations.

## Unit
- **Output in decimal**: Outputs angle values in decimal degrees (e.g., 180.23°)
- **Output in integer**: Outputs angle values in integer format representing hundredths of degrees (e.g., 18023 = 180.23°)

## Output
The node outputs a JSON object with the decoded information:

For absolute position commands (A4) with "Output in decimal" selected:
```json
{
    "payload": {
        "motorId": 0x141,
        "angle": 90.5
    }
}
```

For absolute position commands (A4) with "Output in integer" selected:
```json
{
    "payload": {
        "motorId": 0x141,
        "angle": 9050
    }
}
```

For relative offset commands (A8) with "Output in decimal" selected:
```json
{
    "payload": {
        "motorId": 0x142,
        "offset": 5.0
    }
}
```

For status query commands (94) with "Output in decimal" selected:
```json
{
    "payload": {
        "motorId": 0x141,
        "status": true,
        "angle": 90.5
    }
}
```

## Motor IDs
- Yaw motor (horizontal): `0x141`
- Pitch motor (vertical): `0x142`

## Command Types
- `0xA4`: Absolute position command
- `0xA8`: Relative offset command
- `0x94`: Status query command

## Angle Units
- **Raw Value**: Motor units (hundredths of degrees)
- **Converted Value**: Degrees

## Notes
- The node handles the byte order conversion (little-endian format)
- Error messages are displayed if the input format is invalid
- When "Output in decimal" is selected, the values are more human-readable
- When "Output in integer" is selected, the values match the motor's internal units
- Invalid commands and ACK responses are filtered out with a yellow status indicator

## Technical Notes
- Motor units are in hundredths of degrees (0.01 degree/LSB)
- The raw value is useful for high-precision applications
- The converted value is more human-readable
- Status commands (94) return the current angle of the motor
- ACK responses with second byte 0x2F are automatically filtered
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