placing

platformio.ini

@@ -21,4 +21,5 @@
 platform = atmelavr
 framework = arduino
 board = nanoatmega328
+build_flags = -Wl,-u,vfprintf -lprintf_flt -l
 #targets = upload

src/main.cpp

@@ -12,6 +12,7 @@ LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
 
 #define PIN_RESET 2
 #define PIN_CAR1 3
+#define PIN_LED LED_BUILTIN
 
 typedef struct {
   // input pin for this car
@@ -24,7 +25,7 @@ typedef struct {
 #define PIN_CAR_STARTING 3
 
 // number of cars (4 max)
-#define CAR_COUNT 1
+#define CAR_COUNT 2
 
 // array of cars
 Car cars[CAR_COUNT];
@@ -62,19 +63,38 @@ void resetCars() {
 }
 
 void displayTimers() {
+  short row = 0;
   lcd.clear();
-  for(short i=0; i<CAR_COUNT; i++) {
-    lcd.setCursor(0,i);
-    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);
+
+  // keep track of cars that we've already printed a score for
+  bool seenCar[CAR_COUNT];
+  for (int i=0; i<CAR_COUNT; i++) {
+    seenCar[i] = false;
+  }
+
+  for(short place=0; place<CAR_COUNT; place++) {
+
+    // find which is the fastest car that hasn't already been processed
+    short currentCar = -1;
+    for (short i=0; i<CAR_COUNT; i++) {
+      if (!seenCar[i] && cars[i].elapsedTime != 0 && (currentCar == -1 || cars[i].elapsedTime < cars[currentCar].elapsedTime)) {
+        currentCar = i;
+      }
+    }
+
+    // mark car as seen so we don't show the same car again
+    seenCar[currentCar] = true;
+
+    if (cars[currentCar].elapsedTime != 0) {
+      // only print the score if this car finished
+      lcd.setCursor(0,row++);
+      sprintf(buffer, "%d%s: CAR%d @ %0.2fs", place+1, place==0?"st":(place==1?"nd":(place==2?"rd":"th")) , currentCar+1, cars[currentCar].elapsedTime/1000.0);
+      lcd.print(buffer);
     }
-    lcd.print(buffer);
   }
 }
 
-#define MAX_TIME 10000
+#define MAX_TIME 5000
 
 unsigned long startTime;         // start time in ms
 
@@ -94,10 +114,11 @@ void loop()
       lcd.setCursor(0,0);
       lcd.print("Ready...");
       resetCars();
-      digitalWrite(LED_BUILTIN, LOW);
+      digitalWrite(PIN_LED, HIGH);
     }
   } else {
     if (state == STATE_READY) {
+      digitalWrite(PIN_LED, LOW);
       state = STATE_RUNNING;
       lcd.setCursor(0,0);
       lcd.print("Running!");