How to use a ToF sensor with Raspberry Pi.

This article shows how to use a ToF sensor with Raspberry Pi.

ToF sensor (VL53L1X) was controlled by I2C communication from Raspberry Pi.

Contents

Parts required to use a ToF sensor
Connection of each parts
Python sample code
Operation check of ToF sensor

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Parts required to use a ToF sensor

In the beginning, I show parts required to use a ToF sensor.

ToF sensor

I bought a module with VL53L1X at Switch Science.

( Sorry, link to Japanese shop )

Specifications of ToF sensor.

Size : 13 × 18 × 2 mm
Weight : 0.5 g
Resolution : 1mm
Max range : 400cm
Min range : 4cm
Interface : I2C
Min operating power : 2.6V
Max operating power : 5.5V
Power supply current : 15mA

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Breadboard

This breadboard is a best seller on Amazon.

Jumper wire

This product is a set of male-male, male-female, and female-female.

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Connection of each parts

From here, I show how to connect each part.

GPIO and the 40-pin Header on Raspberry Pi 4

Here is the pinout of the Raspberry Pi.

quotation : Raspberry Pi Documentation

The pinouts of the Raspberry Pi can also be viewed by using the terminal.

Enter the following command in the terminal and the pinouts of the Raspberry Pi will be displayed.

$ pinout

Since I2C communication is used, PIN numbers 3(SDA) and 5(SCL) are used.

Connection of each part

I show the wiring diagram of the ToF sensor and the Raspberry Pi.

Connect SDA and SCL between the ToF sensor and the Raspberry Pi.

The 5V output of the Raspberry Pi is used to power the ToF sensor.

Do not forget to connect GND as well.

Here is a picture of the wiring.

Here is a picture of the front of the ToF sensor.

Note that a ToF sensor may have a protective sticker on it if you just bought it.

Here is a picture of the ToF sensor after the protective sticker has been removed.

Enable I2C communication on the Raspberry Pi.

Go to "Preferences" > "Raspberry Pi Configuration".

( Sorry, Japanese is included. )

On the Interface tab, enable "I2C".

( Sorry, Japanese is included. )

I2C communication is available on Raspberry Pi.

Check the I2C address of the ToF sensor

Check the I2C address of the ToF sensor.

Enter the following command in the terminal.

$ sudo i2cdetect -y 1

If the following image is displayed, the I2C communication is established.

Channel 0x29 can be used for communication with a ToF sensor.

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Python sample code for using a ToF sensor

I show Python sample code for using a ToF sensor.

Install the library for VL53L1X

The library for VL53L1X must be installed in advance.

Enter the following command in the terminal to install the library.

$ sudo pip3 install vl53l1x

Python sample code

Here is a sample code to use a ToF sensor with Raspberry Pi.

### Sample code

import VL53L1X
import time

tof = VL53L1X.VL53L1X(i2c_bus=1, i2c_address=0x29)
print("Python: Initialized")
tof.open()
print("Python: Opened")


time_start = time.time()

try :
    while True:


        ### ------------------- get_time ----------------- ###

        time_end = time.time()
        time_elapsed = time_end - time_start

        print("")
        print("--- Time : {:.1f}s ---".format(time_elapsed))



        ### ------------------- get_distance ----------------- ###

        ### --- Short Range --- ###
        tof.start_ranging(1)    # 1 = Short Range
        distance_mm = tof.get_distance()
        print("Short Range Distance: {}mm".format(distance_mm))
        tof.stop_ranging()

        ### --- Medium Range --- ###
        tof.start_ranging(2)    # 2 = Medium Range
        distance_mm = tof.get_distance()
        print("Medium Range Distance: {}mm".format(distance_mm))
        tof.stop_ranging()

        ### --- Long Range --- ###
        tof.start_ranging(3)    # 3 = Long Range
        distance_mm = tof.get_distance()
        print("Long Range Distance: {}mm".format(distance_mm))
        tof.stop_ranging()


        time.sleep(1)

except KeyboardInterrupt:
        print("\nCtrl+C")

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Operation check of ToF sensor

This video shows a ToF sensor being used to measure distance.

VL53L1X has three measurement modes.

To confirm the characteristics of each ranging mode, I conducted a simple experiment.

Here is a picture of the experimental environment.

Here are the measurement results.

	Short Range	Medium Range	Long Range
50cm	47.6cm	47.5cm	46.2cm
100cm	96.9cm	99.2cm	99.8cm
150cm	154.9cm	156.1cm	157.1cm
200cm	184.1cm	189.5cm	192.2cm
250cm	204.5cm	217.8cm	235.1cm
300cm	166.9cm	205.2cm	255.4cm

When the object distance was close, there was no difference between modes, but when the object distance exceeded 250 cm, an error became larger by using the Short Range mode.

This result is expected to vary depending on the reflectivity of the subject and its shape.

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