Distance Sensor and OLED

How to use OLED screen

Here you have my previous tutorial about it:

• #includes and #defines, before run setup():

#include <SPI.h>   //we need all those nasty libraries for OLED
#include <Wire.h> 
#include <Adafruit_GFX.h> 
#include <Adafruit_SSD1306.h>  
#define OLED_RESET 4 // this is the reset pin, IM NOT USING IT
Adafruit_SSD1306 display(OLED_RESET);

• In the setup() function:

display.begin(SSD1306_SWITCHCAPVCC, 0x3C); 
//initialize with the I2C addr 0x3C (128x64) 
 display.clearDisplay();  // clear the display before start

• In loop() function:

display.setCursor(22,20);        //x,y coordinates
 display.setTextSize(3);         //size of the text
 display.setTextColor(WHITE);    //if you write BLACK it erases things
 display.println(distance);      //print our variable
 display.setCursor(85,20);       //set size,print the units (cm/in)
 display.setTextSize(3); 
 #ifdef CommonSenseMetricSystem//if theres#define CommonSenseMetricSystem
 display.println("cm");        //print "cm" in oled
 #endif 
 #ifdef ImperialNonsenseSystem//if there´s#define ImperialNonsenseSystem
 display.println("in");       //print "in" in oled
 #endif 
 display.display();          //you need to actually display all that data
 delay(500);                 //wait!, human speed
 display.clearDisplay();      //clear black the display

How to use HC-SR04 ultrasonic range

Here you have the datasheet, the HC module sends a burst of pulses and then measures the time that the ultrasound´s echo takes to return to its original place.

• Make a pulse for HC trigger, the HC will do a pulse burst:

long duration, distance; //our beloved variables
 digitalWrite(trigPin, LOW);  //PULSE ___|---|___ 
 delayMicroseconds(2);  
 digitalWrite(trigPin, HIGH); 
 delayMicroseconds(10);  
 digitalWrite(trigPin, LOW);

• PulseIn() is a rare used function, detects the length of the step high (__----__) or low (----___---)

We use #ifdef for only compiling the parts that we need.

duration = pulseIn(echoPin, HIGH); //
 #ifdef CommonSenseMetricSystem 
 distance = (duration/2) / 29.1; 
 #endif 
 #ifdef ImperialNonsenseSystem 
 distance = (duration/2) / 73.914; 
 #endif

• And this for debugging in case your Oled is not working:

Serial.println(distance);//debug