turn on IR LEDs with GPIO

firmware/OpenChrono/OpenChrono.ino

@@ -45,6 +45,9 @@ static void measure() {
 }
 
 void setup() {
+    pinMode(IR_LED_PIN, OUTPUT);
+    digitalWrite(IR_LED_PIN, HIGH);
+
     lcd_init();
     delay(SCREEN_TIMEOUT); // show splash screen
 

firmware/OpenChrono/config.h

@@ -73,6 +73,10 @@
 
 // --------------------------------------
 
+#define IR_LED_PIN 4
+
+// --------------------------------------
+
 // placeholder data for debugging purposes
 
 #define DEBUG_TICK_COUNT 0