Nucleo and HC-SR04 Ultrasonic Sensor example

HC-SR04 is an ultrasonic ranging module that provides 2 cm to 400 cm non-contact measurement function. The ranging accuracy can reach to 3mm and effectual angle is < 15°. It can be powered from a 5V power supply.

HC-SR04 Specifications

Working Voltage: DC 5V
Working Current: 15mA
Working Frequency: 40Hz
Max Range: 4m
Min Range: 2cm
Measuring Angle: 15 degree
Trigger Input Signal: 10µS TTL pulse

Layout

Here is the layout, the Trig is connected to D12 and the Echo is connected to D11. If you change the pins you’ll have to update the code later

Code

In this example we need to import a HCSR04 library into the mBed online compiler, I used this one – https://developer.mbed.org/users/antoniolinux/code/HCSR04/

[codesyntax lang=”cpp”]

// Initialize a pins to perform Serial Communication for receive
// the result of the printf on PC (USB Virtual Com)
// I suggest to use TeraTerm on PC.
// TeraTerm configuration must be: 9600-8-N-1 FlowControl None

/* EXAMPLE */
#include "mbed.h"
#include "hcsr04.h"
 
//D12 TRIGGER D11 ECHO
HCSR04 sensor(D12, D11); 
int main() 
{
    while(1) 
    {
        
     long distance = sensor.distance();   
      printf("distance  %d  \n",distance);
      wait(1.0); // 1 sec  
        
    }
}

[/codesyntax]

Links
HC-SR04 Ultrasonic Module Wave Sensor Ranging Detector Distance Module

NUCLEO-F411RE STM32F411RE Core Board