Add 'main.c'

main.c

@@ -0,0 +1,70 @@
+#define SENSOR_PIN A3
+#define RELAY_PIN 3
+
+#define SENSOR_SAMPLE_COUNT 50
+#define SENSOR_THRESHOLD 50
+#define RELAY_SHUTOFF_DELAY 5000
+
+
+bool RELAY_STATE = HIGH;
+int INDEX = 0;
+int SAMPLES[SENSOR_SAMPLE_COUNT] = {0};
+
+
+int getMaxIntFromArray(int *arr, int len)
+{
+  int maxValue = 0;
+  for (int i = 0; i < len; i++)
+  {
+    if (arr[i] > maxValue)
+    {
+      maxValue = arr[i];
+    }
+  }
+  return maxValue;
+}
+
+
+int getSensorValue()
+{
+  for (int i = 0; i < SENSOR_SAMPLE_COUNT; i++)
+  {
+    INDEX = (INDEX + 1) % SENSOR_SAMPLE_COUNT;
+    SAMPLES[INDEX] = abs(analogRead(SENSOR_PIN) - 512);
+    delay(10);
+  }
+  return getMaxIntFromArray(SAMPLES, SENSOR_SAMPLE_COUNT);
+}
+
+
+void setup()
+{
+  pinMode(RELAY_PIN, OUTPUT);
+  digitalWrite(RELAY_PIN, HIGH);
+}
+
+
+void loop()
+{
+  int sensorValue = getSensorValue();
+  if (sensorValue < SENSOR_THRESHOLD)
+  {
+    if (RELAY_STATE == LOW)
+    {
+      delay(RELAY_SHUTOFF_DELAY);
+      sensorValue = getSensorValue();
+    }
+    
+    if (sensorValue < SENSOR_THRESHOLD)
+    {
+      // Vacuum off.
+      RELAY_STATE = HIGH;
+    }
+  }
+  else
+  {
+    // Vacuum on.
+    RELAY_STATE = LOW;
+  }
+  digitalWrite(RELAY_PIN, RELAY_STATE);
+}