TOF Laser Range Sensor (B)

VL53L1X Distance Sensor

Introduction

The TOF Laser Range Sensor (B) is a TOF-based (time of flight) laser ranging sensor with an embedded MCU and ranging algorithm, which is capable of offering up to 15m measuring range, ±2% accuracy, and 1mm resolution. It supports UART or I2C communication bus, featuring a longer measuring distance and higher light interference resistance capability due to its ultra-narrow FOV, suitable for either indoor or outdoor conditions.
This sensor can be widely used in applications like common distance measuring, robot obstacle avoidance/route planning, as well as drone altitude setting/ceiling detection, and more...

Specification

	TOF Laser Range Sensor	TOF Laser Range Sensor (B)
Typical measuring range	Short range: 0.012 ~ 2.16m	0.10 ~ 15.0m
	Mid range: 0.012 ~ 3.60m
	Long range: 0.01 ~ 5.00m
Typical measuring accuracy	Short range: accuracy ±1.0cm, standard deviation<0.3cm	0.10 ~ 2m ±2cm；2 ~ 15m ±2%
	Mid range: accuracy ±1.0cm, standard deviation<1.5cm
	Long range: accuracy ±1.5cm, standard deviation<[email protected]~3m, standard deviation<8cm@3~5m
Resolution	1mm
Power supply	3.7 ~ 5.2V (reverse-proof)
Operating temperature	-10°C ~ 60°C
Wavelength	940nm (Class1 standard compliant)	750 ~ 830nm compliant with IEC 60825-1:2014 version 3 Class2 standard
Field of view (FOV)	15° ~ 27° (adjustable)	1° ~ 2°
Communication interface	UART (3.3V TTL signal level)
Communication interface	CAN (both of the two ports can be used as CAN simultaneously)	I2C (cascading support, the slave address is 0x08+module ID)
Baudrate	UART: 115200 ~ 3000000bps (921600bps by default)
Baudrate	UART: 115.2Kbps ~ 3000Kbps (921.6Kbps by default)	I2C: up to 400Kbps
Cascade support	UART: supports up to 8x cascades, CAN: supports up to 7x cascades	I2C: supports up to 8x cascades
Ambient light resistance	weak resistance, indoor only	about 100K LUX resistance, suits both indoor and outdoor
Power consumption	290mW (UART active output, long-range mode, 5.0V power supply, 58mA current)	610mW (UART active output, 5.0V power supply, 122mA current)
Weight	2.7g	7.7g
Dimensions (L × W × H)	35.58 × 12 × 8.05mm	22.7 × 28 × 13.6mm

Applications

Unmanned aerial vehicle height setting, ceiling detection
Robot obstacle avoidance
Measuring and detecting
Intelligent gesture control
1-dimension gesture identification

Technology Overview

TOF is an absolute distance detection technology, where the sensor emits calibrated near-infrared light, which is reflected upon encountering an object. By calculating the time or phase difference between light emission and reflection, the sensor converts it into distance information about the captured scene, thus generating depth information. Compared to stereo vision and 3D structured light approaches, TOF offers advantages such as longer working distances, broader applicability, and higher accuracy at longer distances. Therefore, it is commonly used in applications such as proximity detection of individuals, obstacle avoidance for robots, and automatic focusing in cameras. However, in outdoor environments, near-infrared light from sunlight can affect the measurement accuracy of the module.

Function Description

【ID】

ID is one variable designed for distinguishing the different sensors, which is used to identify each sensor during the cascade connection.

【Interface & Baudrate】

TOF Laser Range Sensor (B) supports UART, I2C, and I/O.

UART

The communication baud rate setting range is as follows：

UART Baud Rate	Note
115200,230400,460800,921600,1000000,1200000,2000000,3000000	921600 (by default)

The UART interface mode supports "active output" and "query output":
PC Download:

TOF Assistant (For Windows 7/10 64 bits)
TOF Assistant (For Windows 7/10 32 bits)
Active Output:
- The active output mode can only be used with a single module. In this mode, the module actively outputs measurement information at a frequency of 50 Hz, the format of output data is based on the NLink_TOFSense_Frame0 protocol.
- Users can connect the Sensor to Windows PC by USB to TTL module and configure the module by Waveshare TOFAssistant software. Just like the picture below. You need to click the "Write Parameter" button to save the setting and don't forget to check them by "Read Parameter".

Query Output:
- The query output mode can be used in a single module. In this mode, the controller sends a query command containing the module ID to the desired query module, and the module can output one frame of measurement information. The query command is based on NLink_TOFSense _Read_Frame0 protocol, and the output data from the module is based on the NLink_TOFSense_Frame0 protocol.
- Connect the TOF series products to the Waveshare TOFAssistant software through the USB TO TTL module (line sequence and power supply voltage reference data sheet), click to enter the setting page after the identification is successful, the UART query output mode configuration is as shown in the figure below, after configuring the parameters, you need to click the write parameter button To save the parameters after the parameters are written successfully, you can read the parameters once to confirm whether the parameters are written successfully. (After changing the baud rate parameter of the module, you need to re-plug the USB TO TTL module to automatically identify the module):

I2C

The baudrate rate

I2C baudrate	Description
Max 400KHz	Max 4000KHz, it is defined by the host device

I2C address

I2C address	Description
0x08 ~ 0x77	The default address is 0x08 (7 bits), and the slaver address of the module is 0x08 + ID, you can change the device address by modifying the module ID. Please take care of offset and the behavior bit while communicating. for example, if the device address is 0x08, if you need to write data, you need to add the write bit and the byte sent should be 0x10, if you need to read data, you need to add the read bit and the byte sent should be 0x11.

In the I2C communication mode, the controller sends a reading frame to the expected query module of the specified slave address, and then the information such as the distance of the module can be obtained. In addition, various parameters such as the output mode of the module can also be changed through I2C communication. The reading frame and write frame format follow the protocol NLink_TOFSense_IIC_Frame0. You can connect the sensor to the PC by USB to the TTL module and change the device address (0x08 + ID, the ID should be in the range 0 ~111) by the Waveshare TOFAssistant software. Note that, the Waveshare ToFAssitant software can only support UART mode.

I/O output

In I/O output mode, it doesn't output distance data. The voltage of I/O is toggled when the distance is over the threshold.

When the module is in UART mode, users can connect it to the Windows PC by USB to TTL module and configure the band data by the Waveshare TOFAssistant software. The distance value is converted to high and low-level output through hysteresis comparison. TX/SCL and RX/SDA output complementary levels. The hysteresis comparison diagram is shown in Figure 5. After configuring the parameters, you need to click the Write Parameters button to save the parameters. Note: After switching to I/O mode, you can refer to the FAQ chapter to change back to UART mode.

For example, Band_Start and Bandwidth are both set to 500, which corresponds to 0.5 meters. When the distance measurement value is 0.3 meters, RX is high, TX is low, the distance measurement value increases to 0.8 meters, RX is high, TX is low, and when the distance measurement value exceeds 1 meter, the level is reversed and RX is low, TX is high. When the distance measurement value drops from more than 1 meter to 0.8 meters, RX is low and TX is high. When the distance measurement value drops below 0.5 meters, the level is reversed, RX is high and TX is low.

The range of Band_Start, Bandwidth is 0~15000 and 0~25000.

【Distance Status】

The module can output the current distance status, the user can perform the data processing with the combination of distance status. The meaning of distance status is as follows:

Value	Note
0	Measuring distance is invalid
1	Measuring distance is valid

【Signal Strength】

Indicate the strength of the current return signal, and the larger this value indicates the stronger the return signal.

【Range Precision】

Indicate the precision of the current signal, the smaller the data, the higher the prevision.

【FOV】

The field angle FOV determines the vision scope of TOFSense. The FoV of the ToF Sensor (B) is 1~2°.

【Mode Switch】

If the sensor is in UART mode, users can connect it to the PC and change it to I2C or I/O mode by the Waveshare TOFAssistant software. If the sensor is in I2C mode, users can send commands to switch the mode to UART. Users can check the FAQ chapter about how to change to UART from I/O mode.

Protocol Analysis

The protocol is composed of Frame Header, Function Mark, Data, and Sum Check.
- The Frame Header and Function Mark are fixed values;
- Data is the content of the transmitted data;
- Sum Check is the lowest byte after the addition of Frame Header, Function Mark, and Data (that is, the addition of all the previous bytes).
Agreement composition:

 Frame Header + Function Mark + Data + Sum Check

Note: Protocol packets follow the principle of little-endian mode, that is, the low byte is first and the high byte is last.

The frame:

Protocol	Type	Description
NLINK_TOFSENSE_FRAME0	Fixed length	UART output data, contains the timestamp, distance, distance status, and signal strength, etc.
NLINK_TOFSENSE_READ _FRAME0	Fixed length	UART read, contain device ID
NLINK_TOFSENSE_IIC_FRAME0	Flexible length	I2C data, contain distance, distance status, and signal strength, etc.

NLink_TOFSense_Frame0

- Data Sources: Connect the module to the host computer and configure the UART as active output mode.
- Raw data:

 57 00 ff 00 9e 8f 00 00 ad 08 00 00 03 00 06 41

Analysis table:

Data	Type	Length (Bytes)	Hex	Result
Frame Header	uint8	1	57	0x57
Function Mark	uint8	1	00	0x00
reserved	uint8	1	ff	*
id	uint8	1	00	0
System_time	uint32	4	9e 8f 00 00	36766ms
dis*1000	uint24	3	ad 08 00	2.221m
dis_status	uint8	1	00	0
signal_strength	uint16	2	03 00	3
range_precision	uint8	1	06	6cm
Sum Check	uint8	1	41	0x41

NLink_TOFSense_Read_Frame0

- Data Sources: Connect the module to the host computer, and configure it as UART query output mode. The host device sends the command to query the data

- Raw data:

57 10 FF FF 00 FF FF 63

Analysis table:

Data	Type	Length (Bytes)	Hex	Result
Frame Header	uint8	1	57	0x57
Function Mark	uint8	1	10	0x10
reserved	uint8	2	ff	*
id	uint8	1	00	0
reserved	uint8	2	ff	*
Sum Check	uint8	1	63	0x63

NLink_TOFSense_IIC_Frame0

Device Address: The sensor works as a slaver device, the default device address is 0x08 (7bits), the whole device address is 0x08 + ID, user can change the device address by modifying the ID.

Register address： If the register is NULL, the output is 0xff by default

AD 08 00 00 03 00 FF FF

Analysis table:

I2C communication

Start: starting signal
W: read the flag bit 1
R: Write the flag bit 0
ACK: response
NACK: no response
Stop: stoping signal

Host sends
Slave sends

NLink_TOFSense_Setting_Frame0

- Data Sources:: Setting Commands

Analysis table:

Software

TOF Assistant is the debugging software supporting the TOF laser ranging module. Its main functions are configuration debugging, status display, function application, and firmware upgrade:

Configuration and debugging: used to configure node-related parameters, such as ID, working mode, baud rate, etc.
Functional application: used for application development, such as data import and export, motion track storage, historical track playback, etc.
Firmware upgrade: used to upgrade the product by wired firmware.

Dimensions

Work with Raspberry Pi

Enable UART

Execute the following command to enter the Raspberry Pi configuration:

sudo raspi-config

Choose Interfacing Options -> Serial -> No -> Yes:
You need to disable the login shell and enable the srial port hardware:

Reboot Raspberry Pi:

sudo reboot

Open the /boot/config.txt file and find the following configuration statement to enable the serial port, if not, add it at the end of the file:

enable_uart=1

Reboot to take effect.

Enable I2C Interface

Open a terminal and run the following commands:

sudo raspi-config 
Choose Interfacing Options -> I2C -> Yes.

Reboot Raspberry Pi:

sudo reboot

Module parameter Settings

The UART baud rate of the TOF Laser Range Sensor module needs to be set to 115200 through the host computer;
The effect of using the TOF Laser Range Sensor module on Raspberry Pi is as follows: