43 lines
1.7 KiB
Markdown
43 lines
1.7 KiB
Markdown
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# IMU Data {#spec_imu_data}
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## IMU Request Packet
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| Name | Header | Serial Number |
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| :--- | :----- | :------------ |
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| Bytes | 1 | 4 |
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| Type | uint8_t | uint32_t |
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| Description | 0x5A | First request should be 0, otherwise the last one |
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## IMU Response Packet
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The IMU response packet contains multiple IMU packets, and each IMU packet contains multiple IMU segments.
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| Name | Header | State | Size | IMU Packets | Checksum |
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| :--- | :----- | :---- | :--- | :---------- | :------- |
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| Bytes | 1 | 1 | 2 | ... | 1 |
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| Type | uint8_t | uint8_t | uint16_t | - | uint8_t |
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| Description | 0x5B | 0 is success, others are failed | Content size | IMU packets | Checksum, XOR of all content bytes |
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### IMU Packet
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The IMU packet is an array of IMU datas.
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| Name | Serial Number | Timestamp | Count | IMU Datas |
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| :--- | :------------ | :-------- | :---- | :-------- |
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| Bytes | 4 | 4 | 1 | ... |
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| Type | uint32_t | uint32_t | uint8_t | - |
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| Description | Serial number | IMU basic timestamp | The number of IMU datas | IMU datas |
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### IMU Segment
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| Name | Offset | Frame ID | Accelerometer | Temperature | Gyroscope |
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| :--- | :----- | :------- | :------------ | :---------- | :-------- |
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| Bytes | 2 | 2 | 6 | 2 | 6 |
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| Type | int16_t | uint16_t | int16_t * 3 | int16_t | int16_t * 3 |
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| Description | The timestamp offset | Image frame ID | Accel x,y,z values | IMU temperature | Gyro x,y,z values |
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* Formula for converting the accel & gyro values to real ones: **real = data * range / 0x10000** .
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* ``accel`` default ``range`` is **8 g**, ``gyro`` default ``range`` is **1000 deg/s**.
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* Formula for converting the temperature to real value: **real = data / ratio + offset** .
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* default ``ratio`` is **326.8**, default ``offset`` is **25℃**.
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