WT901SDCL Attitude Angle Sensor

SPECIFICATION

Model: WT901BSDCL

Description: WT901 with SD storage sensor, Built-in battery

Quality system standard: ISO9001:2016

Tilt switch production standard: GB/T191SJ 20873-2016

Criterion of detection: GB/T191SJ 20873-2016

Revision date: 2020-03-18

Links:

• WT901SDCL tutorial (software, manual, etc.)
• WT901SDCL demo video

Catalog

1 Description

The module integrates high-precision gyroscope, accelerometer, and geomagnetic field sensor. Using high-performance microprocessor, advanced dynamics calculation and Kalman dynamic filtering algorithm, it can quickly solve the module's current real-time motion attitude.

The use of advanced digital filtering technology can effectively reduce measurement noise and improve measurement accuracy.

The attitude solver is integrated into the module, and the dynamic Kalman filter algorithm can be used to accurately output the current attitude of the module in a dynamic environment. The attitude measurement accuracy is 0.05 degrees static and 0.1 degree dynamic. Some professional inclinometers!

The module has a built-in voltage stabilization circuit, the working voltage is 3.3V ~ 5V, and the pin level is compatible with 3.3V / 5V embedded system, which is easy to connect.

The module contains a battery, which can be used alone when fully charged.

The module has an SD card inside to record the measured data.

Support serial TTL interface for users to choose the best connection method. The serial port speed is adjustable from 2400bps to 921600bps.

Up to 200Hz data output rate. The input content can be arbitrarily selected, and the output rate can be adjusted from 0.1 to 200Hz.

2 Features

• Voltage: 3.3V ~ 5V
• Current: <40mA
• Battery capacity: 200mAh
• Battery voltage: 3.7V
• Volume: 51.3mm X 36mm X 15mm
• Measurement dimensions: acceleration: 3D, angular velocity: 3D, magnetic field: 3D, angle: 3D.
• Range: Acceleration: ± 2/4/8/16 g (optional), angular velocity: ± 250/500/1000/2000 °/s (optional), X, Z axis ± 180°, Y axis ± 90°.
• Stability: Acceleration: 0.01g, angular velocity 0.05 °/s.
• Stability of attitude measurement: 0.01°.
• Data output content: time, acceleration, angular velocity, angle, magnetic field, port status, quaternion.
• Data output frequency: 0.1Hz ~ 200Hz.
• Data interface: serial port (TTL level, baud rate support 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600)

3 Hardware Connection

Diagram: A visual representation of the sensor module showing its dimensions (36mm width, 51.3mm height, 15mm depth) and the X, Y, Z axes orientation. A USB port is visible.

4 Axial Description

As shown in the figure, the axial direction of the module is indicated: the X axis is upward, the Y axis is left, and the vertical module is outward. The Z axis represents the direction of rotation, defined by the right-hand rule (thumb points to the axial direction, fingers curl in the direction of rotation). The X-axis angle is the angle around the X-axis rotation, the Y-axis angle is around the Y-axis rotation, and the Z-axis angle is around the Z-axis rotation.

5 Hardware Connection Method

5.1 Connecting to a computer

Use the provided data cable to connect the module to a computer. Ensure the SD card is inserted before powering on the module.

Diagram: An illustration shows the sensor module connected via a USB-TTL cable to a laptop computer.

5.2 Indicator status

Charging: When connected to power, the red indicator light is always on, indicating charging. The light turns off upon completion.

SD Card Recording: After inserting the SD card, a blue light flashes for about 1 second, indicating that the SD card is recording data.

6 Software Usage

6.1 How to use

Users who cannot run the upper computer software should download and install .NET Framework 4.0 from microsoft.com.

Connect the product to the computer via the USB cable and power it on. After installing the CH340 driver for the serial port module, the COM port number can be found in the Device Manager.

Diagram: A screenshot of the Windows Device Manager showing "USB-SERIAL CH340 (COM3)" under Ports (COM & LPT).

The driver is CH340. Download link: pan.baidu.com.

Open the MiniIMU.exe software. Navigate to [Data Package / Upper Computer], click the serial port selection menu, and choose the COM number identified in the Device Manager.

Diagram: A screenshot of the MiniIMU software interface. The "Port" dropdown is shown, with "COM7" selected. The "Baud" is set to "9600".

Select "Normal" for the "Type".

Select "9600" for the "Baud" rate. Once configured, the software will display data.

Diagram: A screenshot of the MiniIMU software showing the main interface with Angle X, Y, Z values displayed. A compass-like indicator is also visible.

Clicking "3D" brings up a three-dimensional display interface showing the module's posture.

Diagram: A screenshot of the MiniIMU software's 3D display interface, showing a car model with orientation indicators.

6.2 Restore factory settings

Connect the WT901SDCL module to the computer using the provided cable. Click the "Settings" tab and then "Restore Default". Power on the module again after restoring settings. Note: This requires knowing the module's baud rate beforehand; if it doesn't match, the setting will not take effect.

6.3 Module calibration

Note: Module calibration and configuration should be performed in an online state, indicated in the lower-right corner of the host computer's configuration bar. "Offline" means the host computer is not controlling the module.

Before use, calibrate the module. Calibration includes addition calibration and magnetic field calibration.

The 6-axis algorithm calibration includes Z-axis return to 0 and addition calibration.

Reminder: Calibration and configuration should be done while online. The module requires calibration before use, including accelerometer and magnetic calibration.

6.3.1 Accelerometer Calibration

This calibration removes the accelerometer's zero bias error. Methods:

1. Keep the module stationary and horizontal. In the software's "Config" menu, click "Acceleration" to open the calibration interface.
2. Check the "Auto Calculate" option. The software will calculate the zero bias value. Click "Write parameter".

Diagram: A screenshot of the JY9Config software showing the "Acceleration" calibration tab. Fields for X, Y, Z values and "Auto Calculate" and "Write parameter" buttons are visible.

6.3.2 Magnetic Calibration

This calibration removes the magnetic field sensor's zero offset, which can cause large errors and affect Z-axis angle measurement accuracy.

Methods:

1. Connect the module and computer. Place the module at least 20 cm away from magnetic interference (magnets, iron, etc.). Open the upper computer software.
2. In the settings page, click on the magnetic field button under the calibration bar to enter magnetic field calibration mode. The MagCal window will appear. Click the calibration button.
3. Slowly rotate the module around the three axes to draw data points in three planes. Continue until a regular ellipse is formed, then stop. Click "Write Parameters".

Diagram: Screenshots of the MagCal window showing three charts (chartXZ, chartXY, chartYZ) with data points forming ellipses. Calibration parameters (Current Value, Offset, Range) are displayed.

Note: Data points should stay within the ellipse. If an ellipse cannot be formed, move away from magnetic interference.

Video address: youtube.com

6.4 Z axis To 0

To avoid magnetic interference, you can change the algorithm to Axis 6 and use Z axis to 0.

Reminder: Z axis to 0 is valid for JY61P only. The Z-axis angle is absolute. Setting Z axis to 0 makes the initial angle relative to 0 degrees. If the Z-axis drifts significantly, it can be calibrated. When powered on, the Z axis automatically returns to 0.

Calibration methods: Keep the module static, click "Config", open the configuration bar, and click "Zero Z Angle". The Z axis angle will return to 0 in the module data bar.

Diagram: A screenshot of the configuration interface showing the "Zero Z Angle" option selected.

6.5 Gyroscope Automatic Calibration

This calibrates the angular velocity, and the sensor calibrates automatically.

Diagram: A screenshot of the configuration interface showing the "Gyro Auto Calibrate" option selected.

6.6 Set Return Content

The content of returned data can be customized. Click "Config" to open the configuration bar and select the desired data content options. For example, the default output for JY901 includes acceleration, angular velocity, angle, and magnetic field. Longitude and ground velocity are available when connected to a GPS module.

Diagram: A screenshot of the configuration interface showing the "Content" section with checkboxes for Time, Acceleration, Velocity, Euler angle, Magnetism, Port, Pressure, Latitude, Longitude, Ground velocity, Quaternion, Positioning accuracy, and GPS original.

6.7 Set Return Rate

In the "Config" bar, set the "retrieval rate" from 0.1Hz to 200Hz. The default is 10Hz, with a maximum of 200Hz. 10Hz means 10 packets per second, each containing 33 bytes.

Reminder: With a lot of return content and a low baud rate, the module may automatically reduce the output rate. The default baud rate is 115200.

Diagram: A screenshot of the configuration interface showing the "retrieval rate" dropdown set to "10Hz".

6.8 Set Baud Rate

The module supports multiple baud rates, with 9600 as the default. Change the baud rate only after successfully connecting to the PC program. Select the desired baud rate and click "Change".

Reminder: After changing the baud rate, re-power the module for the change to take effect.

Diagram: A screenshot of the configuration interface showing the "Communication rate" dropdown with various baud rates listed.

6.9 Calibration time

Configuration: Under "Configuration-Time", check the time button to display calibration time in the data interface and time-on-chip time.

Method: In the host computer's configuration, click "Calibration Time" to calibrate. A success message will appear.

Function: Calibrating the time synchronizes the host computer's time with the module's, allowing accurate tracking of data recording times.

Diagram: A screenshot of the configuration interface showing the "Calibration Time" option and a success message.

6.10 Data Recording

The module itself does not have internal memory; data is recorded and saved using the software.

Method: Click "Record" and then "Start" to save data as a file.

Diagram: A screenshot of the MiniIMU software's data recording interface, showing Angle X, Y, Z values and a data table below.

The saved file is a .tsv file in the software's directory. The file contains columns for Time, acceleration (ax, ay, az), angular velocity (wx, wy, wz), angle (AngleX, AngleY, AngleZ), and temperature (T).

Data can be imported into Excel or analyzed in Matlab.

6.11 Installation Direction

The default installation direction is horizontal. For vertical placement, rotate the module 90 degrees around the X-axis and select the "Vertical" option in the "Config" menu. Calibration can be used after setup.

Diagram: An illustration showing the sensor mounted on a wall, indicating "Wall" and "Ground" and the module's orientation.

Diagram: A screenshot of the configuration interface showing the "Direction" dropdown set to "Horizon".

6.12 Set Bandwidth

Bandwidth filters data outside the measurement range. In the "Config" menu, select "Bandwidth" to set it. The default is 20Hz.

Diagram: A screenshot of the configuration interface showing the "Bandwidth" dropdown set to "20 Hz".

6.13 Six axis/ Nine axis Algorithm

JY61P uses the 6-axis algorithm, calculating the Z-axis angle primarily from angular velocity integration.

JY901 uses the 9-axis algorithm, calculating the Z-axis angle from magnetic field data, which prevents drift.

If the JY901 environment has magnetic field disturbances, the 6-axis algorithm can be used.

To switch from 9-axis to 6-axis algorithm: In the PC configuration bar, change the algorithm to "Axis6", then perform additional calibration and Z-axis zeroing.

Reminder: Only JY901 supports algorithm conversion; JY61P cannot convert algorithms.

Diagram: A screenshot of the configuration interface showing the "Algorithm" dropdown with "Axis 9" and "Axis 6" options.

5 SD card storage data

5.1 Method of storing data

1. Insert the SD card into the slot on the back of the module. Power on the module (1-2 seconds). The module will start working and storing data.
2. Data is stored in a TXT file in hexadecimal format.

6.14 SD card data playback

The SD card is used for recording data. Data transfer occurs only when the SD card is inserted.

Each time the SD card is inserted, data is recorded once. The file name increments sequentially (e.g., WIT142.TSV, WIT143.TSV). To read the data, insert the card, remove it after a period, and use a card reader.

Diagram: An image shows the sensor module with an SD card inserted into its slot, and a separate image of a microSD card labeled "16 GB".

The SD card file is readable. On the host computer, open File-Load, select all files, and then select the desired file to run. The data will be displayed as a graph in the upper computer.

Diagram: A screenshot of a file explorer window showing a list of .TSV files, with "WIT4.TSV" selected.

6.15 Text Conversion

Tutorial for converting SD card TSV file format to TXT file format:

1. After playback, click "File Conversion".
2. Once conversion reaches 100%, a prompt will ask whether to open the converted document and show its path.

Click "Yes" to open the document. The figure indicates: 1 - time to convert document, 2 - time to convert data, 3 - time to record data.

Diagram: Screenshots showing the file conversion process in the MiniIMU software.

7. Communication Protocol

Level: TTL level (non-RS232; using RS232 may damage the module).

Baud rate: 2400, 4800, 9600 (default), 19200, 38400, 57600, 115200, 230400, 460800, 921600. Stop bit and parity bit are 0.

7.1 Module to PC Software

7.1.1 Time Output

Data format: 0x55 0x50 YY MM DD hh mm ss msL msH SUM

YY: Year (e.g., 20YY)

MM: Month

DD: Day

hh: Hour

mm: Minute

ss: Second

ms: Millisecond

Millisecond calculate formula: ms=((msH<<8)|msL)

Checksum: Sum=0x55+0x51+YY+MM+DD+hh+mm+ss+ms+TL

7.1.2 Acceleration Output

Data format: 0x55 0x51 AxL AxH AyL AyH AzL AzH TL TH SUM

Calculate formula:

• ax=((AxH<<8)|AxL)/32768*16g (g is Gravity acceleration, 9.8m/s²)
• ay=((AyH<<8)|AyL)/32768*16g (g is Gravity acceleration, 9.8m/s²)
• az=((AzH<<8)|AzL)/32768*16g (g is Gravity acceleration, 9.8m/s²)

Temperature calculated formula:

T=((TH<<8)|TL) /100 °C

Checksum: Sum=0x55+0x51+AxH+AxL+AyH+AyL+AzH+AzL+TH+TL

Note:

1. Data is transmitted in 16-bit hexadecimal, not ASCII code.
2. Each data point is transmitted as a low byte and a high byte, combined into a short type. For example, X-axis acceleration data Ax has AxL as the low byte and AxH as the high byte.

Conversion method: Assuming Data is the actual data, DataH is the high byte, DataL is the low byte part. Then: Data = ((short)DataH<<8) | DataL. Ensure DataH is converted to a signed short type before shifting by 8 bits, and DataL is also a signed short type, to correctly display negative values.

7.1.3 Angular Velocity Output

Data format: 0x55 0x52 wxL wxH wyL wyH wzL wzH TL TH SUM

Calculated formula:

• wx=((wxH<<8)|wxL)/32768*2000 (°/s)
• wy=((wyH<<8)|wyL)/32768*2000 (°/s)
• wz=((wzH<<8)|wzL)/32768*2000 (°/s)

Temperature calculated formula:

T=((TH<<8)|TL) /100 °C

Checksum: Sum=0x55+0x52+wxH+wxL+wyH+wyL+wzH+wzL+TH+TL

7.1.4 Angular Velocity Output

Data format: 0x55 0x53 RollL RollH PitchL PitchH YawL YawH TL TH SUM

Calculated formula:

• Roll (x axis): Roll=((RollH<<8)|RollL)/32768*180(°)
• Pitch (y axis): Pitch=((PitchH<<8)|PitchL)/32768*180(°)
• Yaw (z axis): Yaw=((YawH<<8)|YawL)/32768*180(°)

Temperature calculated formula:

T=((TH<<8)|TL) /100 °C

Checksum: Sum=0x55+0x53+RollH+RollL+PitchH+PitchL+YawH+YawL+TH+TL

Note:

1. Attitude angle uses the Northeast sky coordinate system: X is East, Y is North, Z is skyward. The Euler coordinate system rotation sequence is Z-Y-X.
2. The pitch angle (Y axis) range is ±90 degrees. Angles outside this range may appear to wrap around. Roll angle (X axis) can exceed 180 degrees.
3. Axis coupling means angles are independent only when small. Large attitude changes can affect multiple angles due to coupling.

7.1.5 Magnetic output

Data format: 0x55 0x54 HxL HxH HyL HyH HzL HzH TL TH SUM

Calculated formula:

• Magnetic (x axis): Hx=((HxH<<8)|HxL)
• Magnetic (y axis): Hy=((HyH <<8)|HyL)
• Magnetic (z axis): Hz=((HzH<<8)|HzL)

Temperature calculated formula:

T=((TH<<8)|TL) /100 °C

Checksum: Sum=0x55+0x53+HxH+HxL+HyH+HyL+HzH+HzL+TH+TL

7.1.6 Quaternion

Data format: 0x55 0x59 Q0L Q0H Q1L Q1H Q2L Q2H Q3L Q3H SUM

Calculated formula:

• Q0=((Q0H<<8)|Q0L)/32768
• Q1=((Q1H<<8)|Q1L)/32768
• Q2=((Q2H<<8)|Q2L)/32768
• Q3=((Q3H<<8)|Q3L)/32768

Checksum: Sum=0x55+0x59+Q0L+Q0H+Q1L+Q1H +Q2L+Q2H+Q3L+Q3H

7.2 Software to Module

Reminder:

1. Factory settings default to serial port, baud rate 9600, frame rate 10Hz. Configuration can be done via PC software and is stored even after power down.
2. Data format: 0xFF 0xAA Address DataL DataH

7.2.1 Register Address table

7.2.2 Save Configuration

0xFF 0xAA 0x00 SAVE 0x00

SAVE: Save

• 0: Save current configuration
• 1: set to default setting

7.2.3 Calibrate

0xFF 0xAA 0x01 CALSW 0x00

CALSW: Set calibration mode

• 0: Exit calibration mode
• 1: Enter Gyroscope and Accelerometer calibration mode
• 2: Enter magnetic calibration mode
• 3: Set height to 0

7.2.4 Set Installation direction

0xFF 0xAA 0x23 DIRECTION 0x00

DIRECTION: set installation direction

• 0: set to horizontal installation
• 1: set to vertical installation

7.2.5 Algorithm transition

0xFF 0xAA 0x24 ALG 0x00

ALG: 6-axis/ 9-axis algorithm transition

• 0: set to 9-axis algorithm
• 1: set to 6-axis algorithm

7.2.6 Gyroscope automatic calibration

0xFF 0xAA 0x63 GYRO 0x00

GYRO: gyroscope automatic calibration

• 0: set to gyroscope automatic calibration
• 1: removed to gyroscope automatic calibration

7.2.7 Set return content

0x50 pack: time pack

• 0: Not output 0X50 pack
• 1: Output 0X50 pack

0x51 pack: Acceleration pack

• 0: Not output 0x51 pack
• 1: Output 0x51 pack

0x52 pack: Angular velocity pack

• 0: Not output 0x52 packet
• 1: Output 0x52 pack

0x53 pack: Angle Pack

• 0: Not output 0x53 pack
• 1: Output 0x53 pack

0x54 pack: Magnetic Pack

• 0: Not output 0x54 pack
• 1: Output 0x54 pack

0x55 pack: Port status pack

• 0: Not output 0x55 pack
• 1: Output 0x55 pack

0x56 pack: Atmospheric pressure &Height Pack

• 0: Not output 0x56 pack
• 1: Output 0x56 pack

0x57 pack: Longitude and Latitude Output Pack

• 0: Not output 0x57 pack
• 1: Output 0x57 pack

0x58 pack: GPS speed Pack

• 0: Not output 0x58 pack
• 1: Output 0x58 pack

0x59 pack: Quaternion Pack

• 0: Not output 0x59 pack
• 1: Output 0x59 pack

0x5A pack: Satellite position accuracy

• 0: Not output 0x5A pack
• 1: Output 0x5A pack

7.2.8 Set return rate

0xFF 0xAA 0x03 RATE 0x00

RATE: return rate

• 0x01: 0.1Hz
• 0x02: 0.5Hz
• 0x03: 1Hz
• 0x04: 2Hz
• 0x05: 5Hz
• 0x06: 10Hz (default)
• 0x07: 20Hz
• 0x08: 50Hz
• 0x09: 100Hz
• 0x0a: 125Hz
• 0x0b: 200Hz
• 0x0c: Single
• 0x0d: Not output

After the setup is complete, need to click save, and re-power the module to take effect.

7.2.9 Set baud rate

0xFF 0xAA 0x04 BAUD 0x00

BAUD:

• 0x00: 2400
• 0x01: 4800
• 0x02: 9600 (default)
• 0x03: 19200
• 0x04: 38400
• 0x05: 57600
• 0x06: 115200
• 0x07: 230400
• 0x08: 460800
• 0x09: 921600

7.2.10 Set X axis Acceleration bias

0xFF 0xAA 0x05 AXOFFSETL AXOFFSETH

AXOFFSETL: X axis Acceleration bias low byte

AXOFFSETH: X axis Acceleration bias high byte

AXOFFSET= (AXOFFSETH <<8) | AXOFFSETL

Note: When set the acceleration bias, the output equals the value of the acceleration sensor output value minus the bias value.

7.2.11 Set Y axis Acceleration bias

0xFF 0xAA 0x06 AYOFFSETL AYOFFSETH

AYOFFSETL: Y axis Acceleration bias low byte

AYOFFSETH: Y axis Acceleration bias high byte

AYOFFSET= (AYOFFSETH <<8) | AYOFFSETL

Note: When set the acceleration bias, the output equals the value of the acceleration sensor output value minus the bias value.

7.2.12 Set Z axis Acceleration bias

0xFF 0xAA 0x07 AZOFFSETL AZOFFSETH

AZOFFSETL: Z axis Acceleration bias low byte

AZOFFSETH: Z axis Acceleration bias high byte

AZOFFSET= (AZOFFSETH <<8) | AZOFFSETL

Note: When set the acceleration bias, the output equals the value of the acceleration sensor output value minus the bias value.

7.2.13 Set X axis Angular velocity bias

0xFF 0xAA 0x08 GXOFFSETL GXOFFSETH

GXOFFSETL: Set X axis Angular velocity bias low byte

GXOFFSETH: Set Y axis Angular velocity bias high byte

GXOFFSET= (GXOFFSETH <<8) | GXOFFSETL

Note: When set the Angular velocity bias, the output equals the value of the sensor output value minus the bias value.

7.2.14 Set Y axis Angular velocity bias

0xFF 0xAA 0x09 GYOFFSETL GYOFFSETH

GYOFFSETL: Set X axis Angular velocity bias low byte

GYOFFSETH: Set X axis Angular velocity bias high byte

GYOFFSET= (GYOFFSETH <<8) | GYOFFSETL

Note: When set the Angular velocity bias, the output equals the value of the sensor output value minus the bias value.

7.2.15 Set Z axis Angular velocity bias

0xFF 0xAA 0x0a GXOFFSETL GXOFFSETH

GZOFFSETL: Set Z axis Angular velocity bias low byte

GZOFFSETH: Set Z axis Angular velocity bias low byte

GZOFFSET= (GZOFFSETH <<8) | GZOFFSETL

Note: When set the Angular velocity bias, the output equals the value of the sensor output value minus the bias value.

7.2.16 Set X axis magnetic bias

0xFF 0xAA 0x0b HXOFFSETL HXOFFSETH

HXOFFSETL: Set X axis magnetic bias low byte

HXOFFSETH: Set X axis magnetic bias high byte

HXOFFSET= (HXOFFSETH <<8) | HXOFFSETL

Note: When set the magnetic bias, the output equals the value of the sensor output value minus the bias value.

7.2.17 Set Y axis magnetic bias

0xFF 0xAA 0x0c HXOFFSETL HXOFFSETH

HXOFFSETL: Set Y axis magnetic bias low byte

HXOFFSETH: Set Y axis magnetic bias high byte

HXOFFSET= (HXOFFSETH <<8) | HXOFFSETL

Note: When set the magnetic bias, the output equals the value of the sensor output value minus the bias value.

7.2.18 Set Z axis magnetic bias

0xFF 0xAA 0x0d HXOFFSETL HXOFFSETH

HXOFFSETL: Set Y axis magnetic bias low byte

HXOFFSETH: Set Z axis magnetic bias high byte

HXOFFSET= (HXOFFSETH <<8) | HXOFFSETL

Note: When set the magnetic bias, the output equals the value of the sensor output value minus the bias value.

8 Application Area

Diagram: Images depicting applications in Agricultural machinery, Internet of things, Solar energy, Power monitoring, Medical instruments, Construction machinery, and Geological monitoring.