RX/TX lights not lighting up?

I have an Arduino Due board. There are two sets of RX/TX lights on the board. The set closest to the DC barrel jack are connected to the ATMega16u2, as they light up when ever I use the "programming" port. The other set, which are just above the power and pin 13 leds, what are they connected to? When I use the SerialUSB class, and use the native port, are those leds supposed to light up? I feel like I should know this, but I can't figure out what functions use those LEDs! I know from looking at the pinout diagram at the top of this forum, that they are infact attached to the SAM3X, and that they aren't broken since I tested them with a sketch I made.

Sorry for so many questions, I just want to figure out what function those LEDs are attached to!

Thanks, themavery

Most of us know that DUE was never finished (or better said, it's not finished yet). I believe those LEDs are there because the Arduino/Atmel team wanted to implement additional comm. protocol indicators. If you look at the variant files and specs you'll notice that these LEDs (PA21/PC30) are MMC/SD and SDRAM related signals. Indeed, PA21 is not defined in Atmel Studio (Arduino Due X definitions). I've been using these LEDs like I use LED13 to monitor custom signals saving the use external LEDs.

Regards p

@Palliser

Yes, it is so true that the DUE is not finished (will it ever be finished?), the IDE is technically in beta still. I found out from experimenting, reading, and looking at other documents, that those LEDs are not really attached to anything (other than just the sam3x). Thank you for confirming to me what I learned.

Palliser: Most of us know that DUE was never finished (or better said, it's not finished yet). I believe those LEDs are there because the Arduino/Atmel team wanted to implement additional comm. protocol indicators. If you look at the variant files and specs you'll notice that these LEDs (PA21/PC30) are MMC/SD and SDRAM related signals. Indeed, PA21 is not defined in Atmel Studio (Arduino Due X definitions). I've been using these LEDs like I use LED13 to monitor custom signals saving the use external LEDs.

Regards p

Explanatory note: Given the hardware of the TX and RX leds, functions like digitalWrite will be reversed; I mean: To turn ON the TX led you have to use digitalWrite(73, LOW); or to turn OFF the RX led you have to use digitalWrite(72, HIGH);

p