In this project i will explain how to interface SR04 ultrasonic sensor module with Arduino and display result on OLED display.




Components:

Arduino

SR04 Ultrasonic sensor module

OLED display i2c

Wires and basic tools




Circuit Diagram:

Description: 

1. Connect SR04 ultrasonic sensor power to arduino +5v and GND also connect Trigger and Echo pin to arduino pin 9 and pin 8 as shown in above circuit diagram.
2. In same way connect OLED power to arduino and connect SCL & SDA of oled display to arduino pin A5 and pin A4.
3. Download arduino code and all libraries form download section, compile the code and upload it to your arduino.
4. If you are new to ultrasonic sensors, do visit this post for basic study “SR04 Ultrasonic Sensor Module Basics”

Code:

/******************************************************************
 * Project: Printing utrasonic sensor data on OLED display
 * Author: Pranay Sawarkar
 * Website: www.etechpath.com
 *
 * This example is for a 128x32 pixel monocrome display using i2c
 *
 *****************************************************************/
#include <Ultrasonic.h>
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
Ultrasonic ultrasonic(9, 8);
#define OLED_RESET 4   //(optional)
Adafruit_SSD1306 display(OLED_RESET);
#if (SSD1306_LCDHEIGHT != 32)     // change it to 64 if you are using 128x64 pixel OLED
#error("Height incorrect, please fix Adafruit_SSD1306.h!");
#endif
void setup()
{
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  //display.display();
  //delay(2000);
  display.clearDisplay();
}
void loop ()
{
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.print("Distance: ");
  display.println(ultrasonic.distanceRead());
  display.setCursor(80,0);
  display.print("cm");
  display.display();
  delay(1000);
  display.clearDisplay();
}

 



Downloads:

SR04 Ultrasonic Sensor Module Basics

SR04 Ultrasonic Module Library 

Adafruit GFX Library

Adafruit_SSD1306 OLED Library

Arduino Code

This project is about moving LED matrix display. In this project we will use MAX7219 8×8 LED module for display, Arduino UNO for brain and Bluetooth serial  module for communication. You will need an Android phone for controlling this display.




Things you will need: 

1. Arduino UNO.
2. MAX7219 LED modules – 3Nos.   (You can add many of these for increasing length of display)
3. HC-05 Serial Bluetooth Module.      (You can use any other similar serial Bluetooth module instead )
4. Android Phone.

Circuit Diagram:

Code :

    /*
          8x8 LED Matrix MAX7219 Scrolling Text
              Android Control via Bluetooth
    */
    #include <MaxMatrix.h>
    #include <SoftwareSerial.h>
    #include <avr/pgmspace.h>
    PROGMEM const unsigned char CH[] = {
      3, 8, B00000000, B00000000, B00000000, B00000000, B00000000, // space
      1, 8, B01011111, B00000000, B00000000, B00000000, B00000000, // !
      3, 8, B00000011, B00000000, B00000011, B00000000, B00000000, // "
      5, 8, B00010100, B00111110, B00010100, B00111110, B00010100, // #
      4, 8, B00100100, B01101010, B00101011, B00010010, B00000000, // $
      5, 8, B01100011, B00010011, B00001000, B01100100, B01100011, // %
      5, 8, B00110110, B01001001, B01010110, B00100000, B01010000, // &
      1, 8, B00000011, B00000000, B00000000, B00000000, B00000000, // '
      3, 8, B00011100, B00100010, B01000001, B00000000, B00000000, // (
      3, 8, B01000001, B00100010, B00011100, B00000000, B00000000, // )
      5, 8, B00101000, B00011000, B00001110, B00011000, B00101000, // *
      5, 8, B00001000, B00001000, B00111110, B00001000, B00001000, // +
      2, 8, B10110000, B01110000, B00000000, B00000000, B00000000, // ,
      4, 8, B00001000, B00001000, B00001000, B00001000, B00000000, // -
      2, 8, B01100000, B01100000, B00000000, B00000000, B00000000, // .
      4, 8, B01100000, B00011000, B00000110, B00000001, B00000000, // /
      4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // 0
      3, 8, B01000010, B01111111, B01000000, B00000000, B00000000, // 1
      4, 8, B01100010, B01010001, B01001001, B01000110, B00000000, // 2
      4, 8, B00100010, B01000001, B01001001, B00110110, B00000000, // 3
      4, 8, B00011000, B00010100, B00010010, B01111111, B00000000, // 4
      4, 8, B00100111, B01000101, B01000101, B00111001, B00000000, // 5
      4, 8, B00111110, B01001001, B01001001, B00110000, B00000000, // 6
      4, 8, B01100001, B00010001, B00001001, B00000111, B00000000, // 7
      4, 8, B00110110, B01001001, B01001001, B00110110, B00000000, // 8
      4, 8, B00000110, B01001001, B01001001, B00111110, B00000000, // 9
      2, 8, B01010000, B00000000, B00000000, B00000000, B00000000, // :
      2, 8, B10000000, B01010000, B00000000, B00000000, B00000000, // ;
      3, 8, B00010000, B00101000, B01000100, B00000000, B00000000, // <
      3, 8, B00010100, B00010100, B00010100, B00000000, B00000000, // =
      3, 8, B01000100, B00101000, B00010000, B00000000, B00000000, // >
      4, 8, B00000010, B01011001, B00001001, B00000110, B00000000, // ?
      5, 8, B00111110, B01001001, B01010101, B01011101, B00001110, // @
      4, 8, B01111110, B00010001, B00010001, B01111110, B00000000, // A
      4, 8, B01111111, B01001001, B01001001, B00110110, B00000000, // B
      4, 8, B00111110, B01000001, B01000001, B00100010, B00000000, // C
      4, 8, B01111111, B01000001, B01000001, B00111110, B00000000, // D
      4, 8, B01111111, B01001001, B01001001, B01000001, B00000000, // E
      4, 8, B01111111, B00001001, B00001001, B00000001, B00000000, // F
      4, 8, B00111110, B01000001, B01001001, B01111010, B00000000, // G
      4, 8, B01111111, B00001000, B00001000, B01111111, B00000000, // H
      3, 8, B01000001, B01111111, B01000001, B00000000, B00000000, // I
      4, 8, B00110000, B01000000, B01000001, B00111111, B00000000, // J
      4, 8, B01111111, B00001000, B00010100, B01100011, B00000000, // K
      4, 8, B01111111, B01000000, B01000000, B01000000, B00000000, // L
      5, 8, B01111111, B00000010, B00001100, B00000010, B01111111, // M
      5, 8, B01111111, B00000100, B00001000, B00010000, B01111111, // N
      4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // O
      4, 8, B01111111, B00001001, B00001001, B00000110, B00000000, // P
      4, 8, B00111110, B01000001, B01000001, B10111110, B00000000, // Q
      4, 8, B01111111, B00001001, B00001001, B01110110, B00000000, // R
      4, 8, B01000110, B01001001, B01001001, B00110010, B00000000, // S
      5, 8, B00000001, B00000001, B01111111, B00000001, B00000001, // T
      4, 8, B00111111, B01000000, B01000000, B00111111, B00000000, // U
      5, 8, B00001111, B00110000, B01000000, B00110000, B00001111, // V
      5, 8, B00111111, B01000000, B00111000, B01000000, B00111111, // W
      5, 8, B01100011, B00010100, B00001000, B00010100, B01100011, // X
      5, 8, B00000111, B00001000, B01110000, B00001000, B00000111, // Y
      4, 8, B01100001, B01010001, B01001001, B01000111, B00000000, // Z
      2, 8, B01111111, B01000001, B00000000, B00000000, B00000000, // [
      4, 8, B00000001, B00000110, B00011000, B01100000, B00000000, // \ backslash
      2, 8, B01000001, B01111111, B00000000, B00000000, B00000000, // ]
      3, 8, B00000010, B00000001, B00000010, B00000000, B00000000, // hat
      4, 8, B01000000, B01000000, B01000000, B01000000, B00000000, // _
      2, 8, B00000001, B00000010, B00000000, B00000000, B00000000, // `
      4, 8, B00100000, B01010100, B01010100, B01111000, B00000000, // a
      4, 8, B01111111, B01000100, B01000100, B00111000, B00000000, // b
      4, 8, B00111000, B01000100, B01000100, B00101000, B00000000, // c
      4, 8, B00111000, B01000100, B01000100, B01111111, B00000000, // d
      4, 8, B00111000, B01010100, B01010100, B00011000, B00000000, // e
      3, 8, B00000100, B01111110, B00000101, B00000000, B00000000, // f
      4, 8, B10011000, B10100100, B10100100, B01111000, B00000000, // g
      4, 8, B01111111, B00000100, B00000100, B01111000, B00000000, // h
      3, 8, B01000100, B01111101, B01000000, B00000000, B00000000, // i
      4, 8, B01000000, B10000000, B10000100, B01111101, B00000000, // j
      4, 8, B01111111, B00010000, B00101000, B01000100, B00000000, // k
      3, 8, B01000001, B01111111, B01000000, B00000000, B00000000, // l
      5, 8, B01111100, B00000100, B01111100, B00000100, B01111000, // m
      4, 8, B01111100, B00000100, B00000100, B01111000, B00000000, // n
      4, 8, B00111000, B01000100, B01000100, B00111000, B00000000, // o
      4, 8, B11111100, B00100100, B00100100, B00011000, B00000000, // p
      4, 8, B00011000, B00100100, B00100100, B11111100, B00000000, // q
      4, 8, B01111100, B00001000, B00000100, B00000100, B00000000, // r
      4, 8, B01001000, B01010100, B01010100, B00100100, B00000000, // s
      3, 8, B00000100, B00111111, B01000100, B00000000, B00000000, // t
      4, 8, B00111100, B01000000, B01000000, B01111100, B00000000, // u
      5, 8, B00011100, B00100000, B01000000, B00100000, B00011100, // v
      5, 8, B00111100, B01000000, B00111100, B01000000, B00111100, // w
      5, 8, B01000100, B00101000, B00010000, B00101000, B01000100, // x
      4, 8, B10011100, B10100000, B10100000, B01111100, B00000000, // y
      3, 8, B01100100, B01010100, B01001100, B00000000, B00000000, // z
      3, 8, B00001000, B00110110, B01000001, B00000000, B00000000, // {
      1, 8, B01111111, B00000000, B00000000, B00000000, B00000000, // |
      3, 8, B01000001, B00110110, B00001000, B00000000, B00000000, // }
      4, 8, B00001000, B00000100, B00001000, B00000100, B00000000, // ~
    };
    int dIn = 7;   // DIN pin of MAX7219 module
    int clk = 6;   // CLK pin of MAX7219 module
    int cs = 5;    // CS pin of MAX7219 module
    int maxInUse = 2;    // Number of MAX7219's connected
    MaxMatrix m(dIn, cs, clk, maxInUse);
    SoftwareSerial Bluetooth(8, 7); // Bluetooth
    byte buffer[10];
    char incomebyte;
    int scrollSpeed = 100;
    char text[100] = "www.etechpath.com  "; // Initial text message
    int brightness = 15;
    int count = 0;
    char indicator;
    void setup() {
      m.init(); // MAX7219 initialization
      m.setIntensity(brightness); // initial led matrix intensity, 0-15
      Bluetooth.begin(38400); // Default communication rate of the Bluetooth module
    }
    void loop() {
      // Printing the text
      printStringWithShift(text, scrollSpeed);
      
      if (Bluetooth.available()) {   // Checks whether data is comming from the serial port
        indicator = Bluetooth.read();   // Starts reading the serial port, the first byte from the incoming data
        // If we have pressed the "Send" button from the Android App, clear the previous text
        if (indicator == '1') {
          for (int i = 0; i < 100; i++) {
            text[i] = 0;
            m.clear();
          }
          // Read the whole data/string comming from the phone and put it into text[] array.
          while (Bluetooth.available()) {
            incomebyte = Bluetooth.read();
            text[count] = incomebyte;
            count++;
          }
          count = 0;
        }
        // Adjusting the Scrolling Speed
        else if (indicator == '2') {
          String sS = Bluetooth.readString();
          scrollSpeed = 150 - sS.toInt(); // Milliseconds, subtraction because lower value means higher scrolling speed
        }
        // Adjusting the brightness
        else if (indicator == '3') {
          String sB = Bluetooth.readString();
          brightness = sB.toInt();
          m.setIntensity(brightness);
        }
      }
    }
    void printCharWithShift(char c, int shift_speed) {
      if (c < 32) return;
      c -= 32;
      memcpy_P(buffer, CH + 7 * c, 7);
      m.writeSprite(32, 0, buffer);
      m.setColumn(32 + buffer[0], 0);
      for (int i = 0; i < buffer[0] + 1; i++)
      {
        delay(shift_speed);
        m.shiftLeft(false, false);
      }
    }
    void printStringWithShift(char* s, int shift_speed) {
      while (*s != 0) {
        printCharWithShift(*s, shift_speed);
        s++;
      }
    }
    void printString(char* s)
    {
      int col = 0;
      while (*s != 0)
      {
        if (*s < 32) continue;
        char c = *s - 32;
        memcpy_P(buffer, CH + 7 * c, 7);
        m.writeSprite(col, 0, buffer);
        m.setColumn(col + buffer[0], 0);
        col += buffer[0] + 1;
        s++;
      }
    }

Steps :

1. Connect MAX7219 LED modules with each other as shown in above wiring diagram.
2. Connect led modules data pins to arduino data pins and connect source power as shown in circuit diagram.
3. Now connect HC-05 serial module to RX TX pins of Arduino. Arduino RX to HC-05 TX and arduino TX to HC-05 RX.
4. Download code into arduino using Arduino IDE.
5. Download android application from download section and install it in your phone .
6. Now you can connect your phone with this display using provided application to control matrix display.

Downloads :

1. Android appliation
2. MAX7219 Datasheet
3. MaxMatrix.h

Check this WiFi controlled MAX7219 LED Matrix using ESP-12 NodeMCU module