Make An Ultrasonic Distance Tester with Micro:bit

Today, we are going to make an ultrasonic distance tester with micro:bit and ultrasonic sensor module.

Materials Needed

1 x BBC micro:bit
1 x Octopus:bit
1 x OLED module
1 x HC-SR04 ultrasonic module

Background Knowledge

 

HC-SR04 Basic Principle

HC-SR04 is a kind of ultrasonic distance measuring modules. With this module， we can detect the space time between ultrasonic send and return, then convert it into distance. Here's the basic principle:

• Use the IO port TRIG to trigger distance measure with 10us high electric level at least.
• Automatically send 8 40kHz square wave and check if a signal returns.
• If a signal has returned, then output a high electric level through the IO port TRIG. The duration of high electric level is the time from ultrasonic send and return.

Distance=(high electric level time x sound space (340m/s))/2

Note： Find in the MakeCode for the already sealed ultrasonic library. You don't have to write any complicated drive code but just simplly invoke the library.

Hardware Assembly

 

Step 1

You can refer to the column below for the connection between ultrasonic module and octopus

ultrasonic module	octopus:bit
VCC	VCC
GND	GND
TRIG	P14
ECHO	P15

Step 2

Since the driving voltage of SR04 ultrasonic module is 5V, so we must slide the voltage switch on octopus:bit to the end of 5V.

Step 3

Plug OLED module into IIC cpnnector on octopus:bit.

Once connected, you can see the following picture showed:

Programming

Step 1

Click to open https://makecode.microbit.org/ and enter the programming interface.

Step 2

Search sonar in ADD Package, then add the ultrasonic library.

Step 3

Search OLED in ADD Package, then add the library for OLED module.

Step 4

Initialize OLED screen.

Step 5

Set the pin trig to be P14 and the pin echo to be P15 with cm as unit. And display the data returned on the OLED screen.

Step 6

When you finished your program, you can get the whole code from this link：https://makecode.microbit.org/_CtF2K5HTkarf

Or you can download the code into micro:bit directly through the web page below.

 

Result

Now you have already successfully created a set of ultrasonic measuring device. Point the ultrasonic head to the object you would like to test, then you will see the distance between on the OLED screen.

https://www.elecfreaks.com/12469.html