# TOFSense-M ToF Sensor Metadata

Language: English | [简体中文](tof_sensor.zh-CN.md)

The dataset ToF topic is `/nlink_tofsensem_cascade`. It records a six-node Nooploop TOFSense-M cascade using UART query output in 8x8 mode.

## Collection Configuration

| Field | Value |
| --- | --- |
| Sensor model | Nooploop TOFSense-M |
| Sensor type | Time-of-flight matrix laser ranging sensor |
| ROS topic | `/nlink_tofsensem_cascade` |
| ROS message | `nlink_parser/TofsenseMCascade` |
| Interface | UART |
| Output mode | Query |
| Cascade nodes | 6 |
| Pixel mode | 8x8 |
| Pixels per node | 64 |
| Expected pixels per cascade message | 384 |
| Nominal refresh rate | 15 Hz per node in 8x8 mode |
| UART baud rate | 921600 bps |

## Message Layout

`nlink_parser/TofsenseMCascade` contains `nodes`, an array of `nlink_parser/TofsenseMFrame0`.

Each node has:

| Field | Type | Meaning |
| --- | --- | --- |
| `id` | `uint8` | Module ID in the cascade |
| `system_time` | `uint32` | Sensor-side system time |
| `pixel_count` | `uint8` | Expected to be 64 in this dataset |
| `pixels` | `TofsenseMFrame0Pixel[]` | Pixel data ordered from index 0 to 63 |

Each pixel has:

| Field | Type | Unit | Meaning |
| --- | --- | --- | --- |
| `dis` | `float32` | mm | Distance decoded by the current `nlink_parser` output |
| `dis_status` | `uint8` | code | Per-pixel distance status |
| `signal_strength` | `uint16` | raw count | Return signal strength; larger is stronger |

For validity checks, treat a pixel as usable only when `dis_status == 0` and `dis > 0`.

## Distance Status Codes

| Code | Meaning |
| --- | --- |
| 0 | Measurement usable |
| 1 | Signal strength too low |
| 2 | Phase target |
| 3 | Target noise estimate too high |
| 4 | Target consistency check failed |
| 5 | Measurement not updated |
| 6 | Wraparound not performed, usually the first measurement |
| 7 | Rate inconsistent |
| 8 | Current target signal strength low |
| 9 | Large pulse valid range, possibly due to merged targets |
| 10 | Usable measurement, but no target was detected in the previous detection |
| 11 | Measurement inconsistent |
| 12 | Target ambiguous |
| 13 | Target detected but data inconsistent, usually when a secondary target exists |
| 255 | Target not detected |

## Sensor Specifications

| Parameter | Value |
| --- | --- |
| Range at 600 lux | 1.5 cm to 4 m |
| Range at 60K lux | 1.5 cm to 2 m |
| Range at 100K lux | 1.5 cm to 1.2 m |
| Distance resolution | 1 mm |
| Typical ranging accuracy | +/- 1.5 cm |
| Typical standard deviation | < 1 cm at 4 m indoors / 600 lux |
| Field of view | 45 deg horizontal, 45 deg vertical, 65 deg diagonal |
| Supported pixel modes | 8x8 and 4x4 |
| Refresh rate | 15 Hz at 8x8, 60 Hz at 4x4 |
| Laser wavelength | 940 nm |
| Laser class | Class 1 |
| Typical power | 670 mW |
| UART supply voltage | 3.7 V to 5.2 V |
| CAN supply voltage | 4.2 V to 5.2 V |

The fixed ToF-to-base extrinsic is not available in this dataset version. Use `calibration/robot_v1_template/tof_to_base.yaml` for the explicit calibration status.