WITMOTION WT61 Inclinometer Sensor

Tutorial Link

For tutorials and demonstration videos, please refer to:

• Google Drive
• WITMOTION Youtube Channel
• WT61 Playlist

If you encounter technical issues or require assistance, WITMOTION's engineering team is available to provide support to ensure successful operation of the AHRS sensors.

Contact

Technical Support Contact Info

Application

• AGV Truck
• Platform Stability
• Auto Safety System
• 3D Virtual Reality
• Industrial Control
• Robot
• Car Navigation
• UAV
• Truck-mounted Satellite Antenna Equipment

1 Introduction

The WT61 is a multi-sensor device designed for detecting acceleration, angular velocity, and angle. Its compact size makes it ideal for industrial applications such as condition monitoring and predictive maintenance. By interpreting sensor data through smart algorithms, the WT61 can be configured for a wide range of use cases.

The WT61 is scientifically known as an AHRS IMU sensor, measuring 3-axis angle, angular velocity, and acceleration. Its core strength lies in its algorithm, which accurately calculates three-axis angles.

As an ISO standard accelerometer, the WT61 is utilized where high measurement accuracy is critical. It offers several advantages over competing sensors:

• Heated for best data availability: Features a patented WITMOTION zero-bias automatic detection calibration algorithm, outperforming traditional accelerometer sensors.
• High precision: Measures Roll, Pitch, Yaw (X, Y, Z axes) along with Acceleration and Angular Velocity.
• Low cost of ownership: Includes remote diagnostics and lifetime technical support from the WITMOTION service team.
• Comprehensive development resources: Provides manuals, datasheets, demo videos, free Windows software, an Android APP, and sample code for MCU integration (e.g., 51 serial, STM32, Arduino, Matlab, Raspberry Pi), along with communication protocols.
• Industry Recognition: WITMOTION sensors are highly regarded by thousands of engineers as a recommended solution for attitude measurement.

1.1 Warning Statement

• Applying more than 5 Volts to the sensor wiring can cause permanent damage to the sensor.
• Connecting VCC directly to GND will burn the circuit board.
• For proper instrument grounding, use the original factory-made WITMOTION cable or accessories.
• For secondary development projects or integration, use WITMOTION's compiled sample code.

2 Use Instructions with PC

2.1 PC Connection

The PC software is compatible only with Windows systems.

2.1.1 Serial Connection

Step 1: Connect the sensor with a serial converter.

PIN Connection:

• VCC - 5V
• TX - RX
• RX - TX
• GND - GND

(When connecting to a computer, VCC-5V is recommended.)

Diagram Description: A diagram illustrates the TTL PIN Definition: RED (VCC 5V), YELLOW (TX), GREEN (RX), BLACK (GND). It also shows a connection setup where a PC is linked via a USB-TTL converter to the sensor module.

Recommended tools:

The following tools are recommended:

• 3-in-1 converter
• 6-in-1 converter
• TTL serial cable

Step 2: Unzip the software and install the CH340 or CP2102 driver (depending on the accessory used).

• Link to tutorial of 3-in-1 serial converter/ TTL serial cable (CH340 driver)
• Link to tutorial of 6-in-1 serial converter (CP2102 driver)

Step 3: Connect the converter to the computer and confirm the "COM port" in the Device Manager.

Diagram Description: A screenshot of the Windows Device Manager is shown, displaying a list of devices, including "Silicon Labs CP210x USB to UART Bridge (COM15)" under "Ports (COM & LPT)".

Step 4: Open the software (Minimu.exe). Data will appear after auto-search finishes.

Notice: If the connection is unsuccessful, operate manually. Select the correct COM port and set the baud rate to 115200. Data will then be displayed on the software interface.

2.2 Software Introduction

Link to download software

2.2.1 Main Menu

Diagram Description: A screenshot of the WITMOTION software's main interface is displayed. It shows the "Attitude Measurement System" with Angle X, Y, and Z readings, along with a compass and a pitch/roll indicator. The software includes menus for File, Tools, Record, 3D, Config, Help, and Auto-search, as well as port selection.

Additional Options:

Other Settings:

2.2.2 Menu of Configuration

Diagram Description: A screenshot of the "JY61 Config" window is shown, featuring buttons for "Reset Z-axis Angle", "Acceleration Calibration", and "Sleep". It also includes dropdown menus for Baudrate, Mode, Direction, Static Threshold, and Bandwidth.

2.2.3 Menu of Data

Diagram Description: A screenshot of the WITMOTION software's data display window is shown. It presents real-time data for Acceleration, Angular Velocity, and Angle across X, Y, and Z axes, along with system and chip information. It also includes charts for data visualization and a compass.

2.3 Calibration

Calibration and configuration of the module should be performed in the online state, indicated in the lower right corner of the software configuration bar. An "offline" status means the module is not controlled by the PC software. Calibration is required before using the module.

Each instrument requires calibration upon first use. Users must calibrate the accelerometer and magnetometer; the gyroscope calibrates automatically.

2.3.1 Accelerometer Calibration

Purpose: To remove the zero bias of the accelerometer. Calibration corrects for initial bias errors, ensuring accurate measurements.

Methods:

1. Keep the module stationary and horizontal.
2. Click "Acceleration Calibration" in the "Config" menu of the software.

Diagram Description: A screenshot shows the "JY61 Config" window with the "Acceleration Calibration" button highlighted. The main software window displays angle readings and a pitch/roll indicator.

Result: After approximately 1-2 seconds, the module's axial acceleration values should be around 0, 0, 1g, with X and Y axis angles near 0°. The x-y axis angle accuracy is achieved post-calibration. Note: When the module is horizontal, the Z-axis will show approximately 1g due to gravity.

2.3.2 Reset Z-axis Angle

This function sets the initial Z-axis angle to 0 degrees. If the Z-axis experiences significant drift during use, this calibration can reset it. Upon powering on, the Z-axis will automatically return to 0.

Step:

1. Keep the module static and horizontal.
2. Click the "Config" menu.
3. Click the "Reset Z-axis Angle" option.

Diagram Description: A screenshot shows the "JY61 Config" window with the "Reset Z-axis Angle" button highlighted.

Check the result: The angle of the Z-axis should return to 0 degrees in the module's data display.

2.4 Configuration

2.4.1 Set Baud Rate

The module supports multiple baud rates, with 115200 as the default. To change the baud rate, select the desired rate in the configuration bar, ensuring correct connection between the software and the module.

• Baud rate 115200 corresponds to a return rate of 100Hz.
• Baud rate 9600 corresponds to a return rate of 20Hz.

Note: After changing the baud rate, the module will only output data at the new rate when it is selected in the PC software.

Diagram Description: A screenshot of the "JY61 Config" window displays the Baudrate dropdown menu, showing options like 115200 (100Hz) and 9600 (20Hz).

2.4.2 Data Recording

The sensor module does not have internal memory; data must be recorded and saved on the computer.

Method: Click "Record" and then "Begin" to save data as a TXT file. The file is saved in the "Data.tsv" directory within the upper computer program's installation folder. The file begins with values corresponding to the recorded data.

Recommendation: Pasting the data into an Excel file is highly recommended for better organization and viewing.

2.4.3 Data Playback

A new function allows a BIN file to be created in the record file folder of the installed software each time a recording is made. This BIN file can be used for data playback.

Recorded data playback method:

1. Disconnect the sensor.
2. Click the "File" button and then select "Load".
3. Choose the original path of the software installation and load the BIN file.
4. Click "Run". The binary file will play back, and the rate can be edited during playback.

Diagram Description: Screenshots show the WITMOTION software interface during the data playback process, including file selection and playback with editable rates.

2.4.4 Standby and Wake Up

• Sleep: The module pauses operation and enters standby mode, reducing power consumption.
• Wake up: The module resumes working state from standby.

To enter sleep mode, click the "Sleep" option in the "Config" menu. To wake up, click "Sleep" again.

Diagram Description: A screenshot of the "JY61 Config" window shows the "Sleep" button.

2.4.5 Placement Direction

The default installation direction is horizontal. For vertical installation:

1. Rotate the module 90 degrees around the X-axis.
2. Place the sensor vertically.
3. In the "Config" menu, select "Vertical" for installation direction.

Diagram Description: A screenshot of the "JY61 - Config" window shows the "Direction" dropdown menu with "Horizontal" selected.

2.4.6 Static Threshold

Static Threshold: When the module is stationary, slight changes in angular velocity measured by the gyro chip are detected. The static threshold function sets the output angular velocity to 0 if it falls below a defined threshold.

Setting method: Click the "Still Threshold" option in the PC software's configuration bar to set the threshold. The default value is 0.122°/s.

Diagram Description: A screenshot of the "JY61 Config" window highlights the "Static Threshold" field, showing the default value of "0.122°/s".

2.4.7 Bandwidth

The default bandwidth is 10Hz.

Function:

1. A higher bandwidth setting results in greater fluctuation in the data waveform. Conversely, a lower bandwidth provides smoother data. For example, a 20Hz bandwidth with a 5Hz output rate yields a very steady waveform.
2. Increasing the bandwidth can help resolve data-repeating issues. For instance, a 20Hz bandwidth with a 100Hz retrieval rate may result in repeating data. To ensure no repeating data, the bandwidth should exceed 100Hz.

Diagram Description: Screenshots illustrate data waveforms with different bandwidth settings (e.g., 256Hz, 260Hz), showing increased fluctuation with higher bandwidth.

2.4.8 Set IIC Address

The module supports IIC mode, directly connecting to the MPU6050 chip. In IIC mode, only the raw data (three-axis acceleration and angular velocity) is output; attitude angle is not available.

Switching to IIC mode in the PC software's configuration bar releases the MPU6050's IIC bus, allowing user access to the chip via IIC. Receiving a data packet starting with 0x55 0x50 indicates the module has entered IIC mode.

Diagram Description: A screenshot of the "JY61 Config" window shows the "Mode" dropdown menu with "Serial" and "IIC" options.

3 Use Instructions with Android Phone

For APP configuration details, refer to Chapter 2.2.

3.1 APP Installation

Install the APK file and grant permissions for Location and Storage.

Diagram Description: A screenshot of an Android phone screen shows the WITMOTION app installation process, with permissions for Storage and Location granted, indicating "Installation successful". A list of downloadable files, including the Android APP, is also displayed.

Link to download Android APP

3.2 Hardware Preparation

Connecting to an Android smartphone requires a serial cable and a Type-C or Micro-USB converter, depending on the phone's interface.

Diagram Description: A diagram illustrates a smartphone connected via a USB cable and converter to the sensor. It includes a PIN Definition: RED (VCC 5V), YELLOW (TX), GREEN (RX), BLACK (GND).

3.3 Connection

1. Install the APK file and grant Storage permission.
2. Connect the sensor with a TTL cable. Then, connect the cable to a type-C converter and plug the converter into the phone.

Upon successful connection, a notification "Choose an APP for the USB device" will appear, indicating the device has been detected. Selecting "WitMotion", "JUST ONCE", or "ALWAYS" is optional.

Note: Only the CH340 driver is detectable via the WITMOTION APP.

Diagram Description: A screenshot shows an Android notification prompting the user to "Choose an app for the USB device", with "WitMotion" selected.

Step 3:

Open the APP and choose "6-axis Series" as the sensor series.

Diagram Description: A screenshot of the WITMOTION app interface displays the "Select Module Type" screen, with "6-axis Series" highlighted.

Step 4: Select the baud rate

Select the baud rate as 115200.

Diagram Description: A screenshot of the WITMOTION app shows a "Please choose the baud rate" dialog box with "115200" selected and the "OK" button ready to be pressed.

Data Display

After selection and a brief wait, the data will display automatically.

Diagram Description: Screenshots of the WITMOTION app show the data display screen with charts for Acceleration and Magnetic data, along with numerical readings for ax, ay, az, hx, hy, hz.

3.4 Calibration

3.4.1 Acceleration Calibration

1. Keep the module stationary and horizontal.
2. Click the "Calibration" menu.
3. Click "Acceleration Calibration" and wait for 3 seconds.
4. Verify the result: confirm that there is 1g on Z-axis acceleration.

Diagram Description: A screenshot of the WITMOTION app's "Calibration" menu shows "Acceleration Calibration" selected, along with data output charts and numerical readings.

3.4.2 Reset Z-axis Angle

1. Keep the module stationary and horizontal.
2. Click the "Calibration" menu.
3. Click "Z axis return to zero" and wait for 3 seconds.
4. Check the "Angle Z" data to confirm it is 0°.

Diagram Description: A screenshot of the WITMOTION app's "Calibration" menu shows "Z axis return to zero" selected, along with angle readings.

4 MCU Connection

Diagram Description: A diagram illustrates an MCU connected to the sensor module via VCC, RX, TX, and GND pins.

Link to download all sample code

Link to sample code instructions demo

Notice: Sample code for Linux or Python systems is not currently provided.

4.1 Arduino

• Download link
• Arduino UNO3 Demo Link

4.2 STM32

• Download link

4.3 Raspberry pi

• Tutorial link

4.4 C#

• DEMO link

4.5 C++

• DEMO link

4.6 Matlab

• Receive Sample Code
• Dataplot DEMO