mostly working

src/main.cpp

@@ -17,13 +17,20 @@ elapsedMillis timeElapsed;
 #define PIN_CAR1 3
 
 typedef struct {
+  // input pin for this car
   short pin;
+  // elapsed time for pin (0 means not finished)
   unsigned int elapsedTime;
-} CarTimer;
+} Car;
 
+// assume all cars are on sequential digital pins
 #define PIN_CAR_STARTING 3
+
+// number of cars (4 max)
 #define CAR_COUNT 1
-CarTimer cars[CAR_COUNT];
+
+// array of cars
+Car cars[CAR_COUNT];
 
 // buffer for the LCD line
 char buffer[40];
@@ -42,11 +49,12 @@ void setup()
     pinMode(cars[i].pin, INPUT_PULLUP);
   }
 
+  // initialize LCD
   lcd.begin(20, 4);
   lcd.backlight();
 }
 
-void resetCarTimers() {
+void resetCars() {
   for(short i=0; i<CAR_COUNT; i++) {
     cars[i].elapsedTime = 0;
   }
@@ -56,16 +64,19 @@ void displayTimers() {
   lcd.clear();
   for(short i=0; i<CAR_COUNT; i++) {
     lcd.setCursor(0,i);
-    sprintf(buffer, "Car %d: %dms", i+1, cars[i].elapsedTime);
+    if (cars[i].elapsedTime == 0) {
+      sprintf(buffer, "Car %d: didn't finish", i+1);
+    } else {
+      sprintf(buffer, "Car %d: %dms", i+1, cars[i].elapsedTime);
+    }
     lcd.print(buffer);
   }
 }
 
+#define MAX_TIME 10000
+
 unsigned int startTime;         // start time in ms
 unsigned int elapsedTime;
-bool started = false;
-
-bool allDone;
 
 #define STATE_READY 1
 #define STATE_RUNNING 2
@@ -81,33 +92,39 @@ void loop()
       lcd.clear();
       lcd.setCursor(0,0);
       lcd.print("Ready?");
-      started = false;
-      resetCarTimers();
+      resetCars();
       digitalWrite(LED_BUILTIN, LOW);
     }
   } else {
-    // if we just started, record current millis counter
-    if (!started) {
+    if (state == STATE_READY) {
+      state = STATE_RUNNING;
+      lcd.setCursor(0,0);
+      lcd.print("Running!");
       startTime = timeElapsed;
-      started = true;
     }
+    if (state == STATE_RUNNING) {
 
-    // calculate elapsed time in ms
-    elapsedTime = timeElapsed - startTime;
+      // calculate elapsed time in ms
+      elapsedTime = timeElapsed - startTime;
 
-    allDone = true;
-    for(short i = 0; i<CAR_COUNT; i++) {
-      if (cars[0].elapsedTime == 0) {
-        if (digitalRead(cars[i].pin) == LOW) {
-          cars[i].elapsedTime = elapsedTime;
-        } else {
-          allDone = false;
+      bool allDone = true;
+      for(short i = 0; i<CAR_COUNT; i++) {
+        if (cars[0].elapsedTime == 0) {
+          if (digitalRead(cars[i].pin) == LOW) {
+            // car finished, record time
+            cars[i].elapsedTime = elapsedTime;
+          } else {
+            allDone = false;
+          }
         }
       }
-    }
 
-    if (allDone) {
-      displayTimers();
+      // stop race if all cars are done or MAX TIME exceeded
+      if (allDone || elapsedTime > MAX_TIME) {
+        state = STATE_DONE;
+        displayTimers();
+      }
+
     }
 
   }