Example 3 Patch

examples/Example3_Trigger_Echo/Example3_Trigger_Echo.ino

@@ -1,80 +1,61 @@
-/* SparkFun Ulrasonic Distance Sensor - Example 3 - Distance using Trigger and Echo Pins
+/* SparkFun Ultrasonic Distance Sensor - Example 3 - Distance Using Trigger and Echo Pins
  * 
  * Product: 
- *  *  SparkFun Qwiic Ultrasonic Distance Sensor - HC-SR04 (SEN-1XXXX)
- *  *  https://www.sparkfun.com/1XXXX
+ *  *  SparkFun Qwiic Ultrasonic Distance Sensor - HC-SR04 (SEN-24805)
+ *  *  https://www.sparkfun.com/products/24805
  * 
- * Written By: Elias Santistevan
- * Date: 06/2024
+ * Written By: Elias Santistevan and Xavior Pautin
+ * Date: 09/2024
  *
  * SPDX-License-Identifier: MIT
  *
  * Copyright (c) 2024 SparkFun Electronics
  */
-#include "SparkFun_Qwiic_Ultrasonic_Arduino_Library.h"
-
-// Create an ultrasonic sensor object
-QwiicUltrasonic myUltrasonic;
-
-// Here we set the device address. Note that an older version of the Qwiic
-// Ultrasonic firmware used a default address of 0x00. If yours uses 0x00,
-// you'll need to change the address below. It is also recommended to run
-// Example 2 to change the address to the new default.
-uint8_t deviceAddress = kQwiicUltrasonicDefaultAddress; // 0x2F
-// uint8_t deviceAddress = 0x00;
-
-// Adjust these to your setup.
+// Using the echo and trigger breakout pins does not require a QWIIC connector I2C connection
+// Adjust these pins to your setup
 const int triggerPin = 7; // Trigger Pin of Ultrasonic Sensor
 const int echoPin = 8; // Echo Pin of Ultrasonic Sensor
 
 // Used for distance calculation
 float distance = 0.0;
 float duration = 0.0;
-const float speedOfSound = 340.00; // Speed of sound in m/s
-const float millisPerSecond= 1000.00; // Number of milliseconds in a second
-
-void setup() {
-
-  Wire.begin(); 
+const float speedOfSound = 0.343; // Speed of sound in mm/us
 
-  Serial.begin(115200);  
-  Serial.println("Ultrasonic Distance Sensor - Example 2 Distance using Trigger and Echo Pins.");
+void setup() {
+  Serial.begin(115200);
+  Serial.println("Ultrasonic Distance Sensor - Example 3 Distance using Trigger and Echo Pins");
 
   pinMode(triggerPin, OUTPUT);
   pinMode(echoPin, INPUT);
-
-  // Attempt to begin the sensor
-  while (myUltrasonic.begin(deviceAddress) == false)
-  {
-    Serial.println("Ultrasonic sensor not connected, check your wiring and I2C address!");
-    delay(2000);
-  }
-
-  Serial.println("Ultrasonic sensor connected!");
 }
 
 void loop() {
-
+  // Required pulse to trigger the ultrasonic sensor
+  // delayMicroseconds() must be greater than 10us, but less than 200us
+  // 10 microseconds is the minimum pulse width listed by the manufacturer
+  // 200 microseconds is the approximate delay between the rise of the trigger pulse
+  // and fall of the echo pulse
   digitalWrite(triggerPin, HIGH);
-  delay(5);
+  delayMicroseconds(50);
   digitalWrite(triggerPin, LOW);
-  // We don't want continually trigger while data is being retrieved from the sensor.
 
-  duration = pulseIn(echoPin, HIGH);
-  // Time until sound detected * speed of sound * conversion to mm 
+  // pulseIn() set LOW because the echo pin of the sensor outputs a negative pulse from HIGH to LOW
+  // pulseIn() duration is in microseconds
+  duration = pulseIn(echoPin, LOW);
+
   // Divide by two because we only want the time the wave traveled to the object, 
   // not to the object and back.
-  distance = (duration * speedOfSound * millisPerSecond) / 2; 
+  distance = (duration * speedOfSound) / 2;
 
   // Print measurement
   Serial.print("Distance (mm): ");
-  Serial.println(distance);
+  Serial.println(distance, 1); // Print to 1 decimal place
 
-  //Serial.println("Distance (cm): "); 
-  //Serial.print((distance / 10.0), 2);         
+  // Serial.print("Distance (cm): ");
+  // Serial.println((distance / 10.0), 2); // Print to 2 decimal places
 
-  //Serial.println("Distace (in): "); 
-  //Serial.print((distance / 25.4), 2);         
+  // Serial.print("Distace (in): ");
+  // Serial.println((distance / 25.4), 2); // Print to 2 decimal places
 
-  delay(500);
+  delay(500); // Must be no less than 25ms to ensure full 400cm sensor range
 }