Benewake TFS20-L User Manual

This user manual contains the introduction, use, and maintenance of the TFS20-L LIDAR. Please read this manual carefully before formal use, and strictly follow the steps described in the manual during use to avoid product damage, property loss, personal injury, or violation of product warranty terms. If you encounter problems that cannot be solved during use, please contact Benewake staff for assistance.

Contact Details

Official website: en.benewake.com

For technical questions, please contact: support@benewake.com

For sales inquiries or to request a brochure, please contact: bw@benewake.com

Contact number: +86-135 8178 8602

Headquarter Address

Benewake (Beijing) Co., Ltd.
3rd Floor, Haiguo Jiaye Sci-Tech Park, Haidian District, Beijing, China

Copyright Notice

This User Manual is copyright © of Benewake. Please do not modify, delete, or translate the description of this manual's contents without the official written permission from Benewake.

Disclaimer

The TFS20-L product is constantly being improved, and its specifications and parameters will undergo iterative changes. Please refer to the official website for the latest version.

1 Product Overview

This chapter mainly introduces the measuring principle, technical specifications, structural description, equipment coordinates, and field of view distribution of the TFS20-L LIDAR.

1.1 Measuring principle

TFS20-L is a miniaturized single-point LiDAR module that measures distance based on direct measurement of time of flight (dToF). The laser at the transmitting end collimates and emits a pulsed laser signal through the transmitting lens. After being reflected by the object being measured, the echo signal enters the receiving lens and is detected by the high-sensitivity SPAD detector at the receiving end. The time difference between the transmission and echo signals can be calculated, and the distance between the object being measured and the LiDAR can be calculated based on the speed of light.

1.2 Technical specifications

^© The accuracy is based on 25 °C, 90% reflectivity condition, and any changes in environmental conditions may cause changes in the measurement results.
^® The repeatability is based on 25 °C indoors and 90% reflectivity condition, and any changes in environmental conditions may cause changes in the measurement results.
^® The peak current is measured at room temperature.

1.3 Structural appearance

The overall appearance of the LiDAR is as shown in the figure below:

Figure 1: TFS20-L Dimensions

The TFS20-L LiDAR module has the following approximate dimensions: Length 21.0 mm ± 0.2 mm, Width 15 mm ± 0.2 mm, Height 7.87 mm ± 0.2 mm. Other detailed measurements are provided in the diagram.

2 Hardware Interface and Protocol

This section introduces the hardware and protocol information of the TFS20-L LIDAR.

2.1 Pin sequence description

The connector terminal model is WF08006-01207, and the terminal spacing is 0.8mm.

Figure 2: TFS20-L pin sequence

The module supports two communication modes: UART and IIC. However, when powered on, only one interface can be selected for operation.

UART Mode: Connect the INT pin (Pin 5) to ground when powering on.

IIC Mode: When powered on, the INT pin (Pin 5) needs to be pulled up with a 4.7K resistor or left floating.

2.2 Serial data communication

The baud rate can be set to 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600. The default baud rate of TFS20-L is 115200. When the wrong baud rate is configured, it is reset to 115200.

2.3 Serial port output format

Each data packet consists of 9 bytes of hexadecimal numbers, see the following table for details:

Data code explanation:

• Byte0: 0x59, frame header, same for each frame
• Byte1: 0x59, frame header, same for each frame
• Byte2: Dist_L, distance value low 8 bits
• Byte3: Dist_H, distance value high 8 bits
• Byte4: Strength_L, low 8 bits
• Byte5: Strength_H, high 8 bits
• Byte6: Temp_L, low 8 bits
• Byte7: Temp_H, high 8 bits
• Byte8: Checksum is the lower 8 bits of the cumulative sum of the first 8 bytes.

2.4 I2C Communication

Pull up a 4.7K resistor on pin 5 or leave it hanging; TFS20-L enters I2C mode. Then its pin 3 is used as SDA data and pin 4 is the SCL clock sending data.

TFS20-L supports up to 400kbps clock speed as a slave machine and its default address is 0x10. For more information about the I2C register table, refer to Appendix I2C register table.

1. Firmware version V1.4.6 and above supports I2C communication. If the firmware version is lower than V1.4.6 or if there are any communication issues, please upgrade the firmware or contact technical support.
2. In this document, the address of the I2C slave device is a 7-bit value with a value range [0x08, 0x77] ([08, 119] in decimal). For the first byte after I2C releases a start signal, the 7-bit address should be shifted leftward for one bit (i.e., multiplied with 2), and then filled with the read-write sign on the lowest bit. For TF-Luna, the default address of the slave device is 0x10, the address for write operations is 0x20, and the address for read operations is 0x21.
After a write operation on the I2C register, it takes TFS20-L some time to process. If users need to read the value from the register for validation purposes, we recommend waiting for 100ms after the write operation, prior to the next read operation.

Write register timing:

Start -> Slave Addr -> W -> Ack -> Register Addr -> Ack -> Data1 -> Ack -> ... -> DataN -> Ack -> Stop

Read register timing:

Start -> Slave Addr -> W -> Ack -> Register Addr -> Ack -> Stop

Start -> Slave Addr -> R -> Ack -> Data1 -> Ack -> ... -> DataN -> Nack -> Stop

3 Custom Configuration

3.1 Frame definition

Customers can customize some parameters of TFS20-L, such as data frame format, frame rate, etc., which can be changed by sending specific commands. All parameters will be saved in Flash after successful configuration, and there is no need to configure them again when powering on again.

Please follow specific formats and rules when configuring parameters and avoid sending random commands.

Note: All configuration commands are sent in hexadecimal (HEX).

Command encoding explanation:

• Byte0: Header: Fixed to 0x5A
• Byte1: Len: The length of the command frame (unit: Byte)
• Byte2: ID: Identifies the function of each command
• Byte3-N-2: Data: Different meanings and lengths in different ID command frames
• ByteN-1: Checksum: the lower 8 bits of the sum of the first N-2 bytes

3.2 Custom configuration

TFS20-L released several configuration parameters. These parameters, such as data format, frame rate, could be modified by certain command. All the parameters will be stored in flash after configured successfully and customers don't need to configure again when restart.

Please change the parameter according to certain requirements and do not frequently try irrelevant instructions. Please configure the product according to the requirements of the datasheet and don't send unstated commands.

To set the relevant parameters of TFS20-L, first connect TFS20-L to PC. For the connection method, refer to sub-section 4.2. Send relevant configuration instructions to the sensor through TF GUI software or other serial port debugging software; customers can also send relevant instructions through their own serial port tools.

After sending the parameter configuration instructions, the power needs to be turned off and settings are saved as default.

1. This command is mainly used to adjust the output frequency of the sensor. The default value of the output frequency is 100Hz, and custom configuration is supported, supporting frequencies are 0, 20, 50, 100, and 250Hz.
2. The baud rate can be set to 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600. The default baud rate of TFS20-L is 115200. When the wrong baud rate is configured, it is reset to 115200.
3. An enable data-output command must be sent each time the power is turned on.
4. 'SU' stands for checksum and puts the lower 8 bits into the command. For example, to change the baud rate to 460800, first change 460800 to HEX (0x00 07 08 00), then calculate the checksum to 0x77, and you can get the following instruction – 5A 08 06 00 08 07 00 77.
5. There is no need to send the save settings command. Sending a specific configuration command will take effect and be saved immediately.
Do not send the command that is not in the list above.

4 Quick Test Guide

4.1 Tools required for test

The following tools are required for testing:

• TFS20-L module
• TTL-USB converter
• USB cable
• PC
• Test Software

Figure 3: LIDAR and PC interfacing

The setup involves connecting the TFS20-L module to a TTL-USB board using a USB cable, and then connecting the USB cable to the PC.

4.2 Test procedures

1. Download the test software

   Download the latest version of the test software for TFS20-L from the Benewake official website: https://en.benewake.com/DataDownload/index_pid_20_lcid_99.html

   Note: Please turn off the anti-virus software before decompressing the host computer software to avoid the files in the host computer software being deleted as viruses. The host computer currently only supports running on Windows systems.

2. Connection of the hardware

   Connect "TFS20-L", "TTL-USB board" and "USB cable". Make sure there is no loose connection. Then connect "USB cable" with "PC". As shown in the above image.

3. Connection with software

   Run GUI software, select "TFmini/TFmini-S" and select automatically recognized communication port (here it is "COM9"), choose the right baud rate (here it is "115200"), as shown in the following image.

   Figure 4: GUI software and LiDAR interfacing

   Then click "CONNECT". Upon successful connection, the continuous graph of the output data will be displayed in area "TIME LINE CHART". Besides, the real-time data of the current measured distance (Dist), effective data points per second (Effective Points) and signal strength (Strength) will be displayed in area "REAL TIME DATA".

   1. If no data is available in area "TIME LINE CHART", please check the wire connection and sequence. When TFS20-L is successfully powered on, there will be a faint red light inside the transmitting lens viewing from the front using a mobile phone camera or any other IR light detecting device.
   2. The value of distance output (Dist) may vary with the output unit, which is cm by default. If the unit of distance is changed to the unit-mm with a specific command, and the PC software will be unable to identify it, and so the unit of "TIME LINE CHART" will still be cm. For example, the actual TFS20-L measurement is 1m, the distance value of TFS20-L is 1000 in mm, the value read by the PC software also is 1000, but the unit will not change and still display cm.

5 Q&A

1. Problem: After the LiDAR is connected to the host computer, there is no data output.

   Cause-1: TTL-USB board connection is bad.

   Solution: Check whether the connection between TTL-USB board, TFS20-L and PC is correct and reliable.

   Cause-2: The serial port driver is not installed correctly.

   Solution: Re-plug the USB cable and try to re-install the driver, or search the Internet for the driver to download and install. If you still cannot use the host computer normally, please contact our technical support.

2. Question: TFS20-L will heat up after working for a period of time.

   Explanation: This is the normal working state of the product. After the chip and circuit board continue to work, slight heating is normal.

3. Problem: TFS20-L has no data output.

   Cause-1: The V1.4.0 version does not output data by default when powered on, and you need to send an output enable command (as mentioned in Table 5).

   Solution: Send the output enable command 5A 05 07 01 67 after powering on.

   Cause-2: The product will be strictly inspected before leaving our factory, ensuring that all the shipped products can work normally. However, some abnormal working matters maybe still occur because of incidents during the transportation or use.

   Solution: Check whether the power supply is normal and whether the voltage is within the rated voltage range. If the power supply is normal, there should be a faint red light in the TFS20-L transmitting lens. Check whether the wiring sequence of TFS20-L is correct and whether the connection is reliable. Check whether the data parsing is correct. Please parse it according to the data format described in the manual. If the problem is still not solved, please contact technical support.

4. Question: Does TFS20-L support ultra-low power mode?

   Answer: No, it does not support. The current standby power consumption is about 145 mW. The average power consumption is about 430 mW. If powered by a 10000mAh battery, it can last about 6 days.

Appendix

I2C REGISTER TABLE