ESP32でミニカーを作る #4 距離を表示する編（おおたfab 電子工作初心者勉強会）

//-----------------------------------------------------
// esp32_mouse2-dest.ino
// 
// for XIAO ESP32C6
//
// 2025/06/29
//-----------------------------------------------------
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library. 
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

const int TRIG_PIN = 18;
const int ECHO_PIN = 20;

// Anything over 400 cm (23200 us pulse) is "out of range"
const unsigned int MAX_DIST = 23200;

/* XIAO ESP32C6
DRV       ESP32
---------------
AIN1 --- GPIO0
AIN2 --- GPIO1
BIN1 --- GPIO2
BIN2 --- GPIO21
*/

const int LP = 0; // AIN1   LEFT PLUS
const int LM = 1; // AIN2   LEFT MINUS
const int RP = 2; // BIN1   RIGHT MINUS
const int RM = 21; // BIN2   RIGHT PLUS

void setup()
{
  Serial.begin(9600);

  // The Trigger pin will tell the sensor to range find
  pinMode(TRIG_PIN, OUTPUT);
  digitalWrite(TRIG_PIN, LOW);

  //Set Echo pin as input to measure the duration of 
  //pulses coming back from the distance sensor
  pinMode(ECHO_PIN, INPUT);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  // Show initial display buffer contents on the screen --
  // the library initializes this with an Adafruit splash screen.
  display.display();
  delay(2000); // Pause for 2 seconds

  // Clear the buffer
  display.clearDisplay();
  display.setTextSize(3);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0,0);             // Start at top-left corner
  display.println(F("Hello, world!"));
  display.display();
  delay(2000);

  analogWrite(LP,0);
  analogWrite(LM,0);
  analogWrite(RP,0);
  analogWrite(RM,0);
}

void loop() //RUN ZIGZAG
{
  TTL();
  delay(500);
  TTR();
  delay(500);
  
  display.clearDisplay();
  display.setCursor(0,0);             // Start at top-left corner
  display.println(dest());
  display.display();
}

void TTL(void) // trun to left
{
  analogWrite(LP,250);
  analogWrite(RP,100);
}

void TTR(void) // trun to right
{
  analogWrite(LP,100);
  analogWrite(RP,250);
}

float dest() {

  unsigned long t1;
  unsigned long t2;
  unsigned long pulse_width;
  float cm;
  float inches;

  // Hold the trigger pin high for at least 10 us
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Wait for pulse on echo pin
  while ( digitalRead(ECHO_PIN) == 0 );

  // Measure how long the echo pin was held high (pulse width)
  // Note: the micros() counter will overflow after ~70 min
  t1 = micros();
  while ( digitalRead(ECHO_PIN) == 1);
  t2 = micros();
  pulse_width = t2 - t1;

  // Calculate distance in centimeters and inches. The constants
  // are found in the datasheet, and calculated from the assumed speed
  //of sound in air at sea level (~340 m/s).
  cm = pulse_width / 58.0;
  //inches = pulse_width / 148.0;

  // Print out results
  if ( pulse_width > MAX_DIST ) {
    Serial.println("Out of range");
  } else {
    Serial.print(cm);
    Serial.println(" cm");
    //Serial.print(inches);
    //Serial.println(" in");
  }

  return(cm);
}