hello-world/lcd-1602A/lcd-1602A.ino

@@ -1,4 +1,3 @@
-#include <Wire.h>
 #include <LiquidCrystal_I2C.h>
 
 /*

sampling/avg/avg.ino

@@ -0,0 +1,133 @@
+#include <LiquidCrystal_I2C.h>
+
+/*
+ * Arduino UNO:
+ *
+ *   GND -> GND
+ *   5V  -> VCC
+ *   A4  -> SDA
+ *   A5  -> SDL
+ *
+ */
+LiquidCrystal_I2C lcd(0x27, 16, 2);
+
+double ema = 0;
+
+/*
+ * Timing vars (milliseconds)
+ */
+unsigned long lastRead = 0;
+unsigned long lastWrite = 0;
+const unsigned long interval = 2000;
+
+// If no sensor, can use a PRNG
+bool pseudoRandomNumberGenerator = true;
+const int seed = 0;
+
+// EMA vars
+double alpha = 0.1;
+
+const char * sensorName = "SR04";
+const int dp = pseudoRandomNumberGenerator ? 0 : 2;
+
+// HC-SR04 Pins
+const int trigPin = 3;
+const int echoPin = 2;
+
+// Function to read distance in cm
+float readDistance() {
+  // Enforce minimum 60ms delay between readings to prevent ghost echoes
+  if (millis() - lastRead < 60) {
+    return -1.0; // Return invalid flag if called too soon
+  }
+
+  // Clear trigPin
+  digitalWrite(trigPin, LOW);
+  delayMicroseconds(2);
+  
+  // Send 10us pulse
+  digitalWrite(trigPin, HIGH);
+  delayMicroseconds(10);
+  digitalWrite(trigPin, LOW);
+  
+  // Update last read time immediately after triggering
+  lastRead = millis();
+
+  // Read echo pulse duration (timeout 30000us = ~5 meters)
+  long duration = pulseIn(echoPin, HIGH, 30000);
+  
+  // Handle timeout (no echo received)
+  if (duration == 0) {
+    return -1.0; // Return invalid flag
+  }
+  
+  // Calculate distance: (duration * speed of sound) / 2
+  float distance = (duration * 0.0343) / 2.0;
+  return distance;
+}
+
+int myRead(){
+  return readDistance();
+}
+
+int read(){
+  if (pseudoRandomNumberGenerator)
+  { 
+    return random(0, 1024);
+  }
+  else
+  {
+    return myRead();
+  }
+}
+
+void display(){
+  lcd.print("EMA: ");
+  lcd.print(ema, dp);
+  lcd.print("   ");
+}
+
+void setup() {
+  lcd.init();
+  lcd.begin(16, 2);
+  lcd.backlight();
+  lcd.clear();
+
+  // Initialize HC-SR04 pins
+  pinMode(trigPin, OUTPUT);
+  pinMode(echoPin, INPUT);
+
+  if (pseudoRandomNumberGenerator)
+  { 
+    randomSeed(seed);
+  }
+  ema = read();
+  
+  lcd.setCursor(0, 0);
+  if (pseudoRandomNumberGenerator)
+  {
+    lcd.print("Sampling PRNG...");
+  }
+  else
+  {
+    lcd.print("Sampling ");
+    lcd.print(sensorName);
+    lcd.print("...");
+  }
+}
+
+void loop() {
+  long curMillis = millis();
+  int raw = read();
+
+  if (raw >= 0){
+    ema = (raw * alpha) + (ema * (1.0 - alpha));
+  }
+
+  if (curMillis - lastWrite >= interval)
+  {
+    lastWrite = curMillis;
+    lcd.setCursor(0, 1);
+    display();
+  }
+}