   }
 }
 
+// Callback when the CBL2 class has successfully received a variable
+// from the attached calculator.
 int onGetAsCBL2(uint8_t type, enum Endpoint model, int datalen) {
   Serial.print("Got variable of type ");
   Serial.print(type);
   Serial.print(" from endpoint of type ");
   Serial.println((int)model);
   
+  // We only want to handle lists.
   if (type != VarTypes82::VarRList)
     return -1;
 
   // Turn the LEDs on or off
   uint16_t list_len = sizeWordToInt(&(data[0]));			// Convert 2-byte size word to int
   if (list_len == 1) {
-    // It is a 1-element list now
-	int value = (int)TIVar::realToFloat8x(&data[2], model);	// First list element starts here
+    // It is indeed a 1-element list
+	int value = (int)TIVar::realToFloat8x(&data[2], model);	// First list element starts after 2-byte size word
     Serial.print("Received value ");
     Serial.println(value);
     for(int i = 0; i < LED_PIN_COUNT; i++) {

  return 0;
}

int onSendAsCBL2(uint8_t type, enum Endpoint model, int* headerlen,
                 int* datalen, data_callback* data_callback)
{

const int lineRed = DEFAULT_TIP;
const int lineWhite = DEFAULT_RING;

// Specify the number of LEDs to control, and to which
// digital pin each LED is attached.
#if defined(__MSP432P401R__)		// MSP432 target
#define LED_PIN_COUNT 4
const int ledPins[LED_PIN_COUNT] = {78, 75, 76, 77};
