Arduino Mega 2560 pin functions, possible damage

Development Tools IDE 1.x
1

I'm using a HacroCam shield (www.hacromatic.com) with an Arduino Mega 2560. The HC is designed to be used as a shield on an Uno, which has A4 for SDA and A5 for SCL. The Mega uses pins 20 and 21 for SDA and SCL, however, so I've wired the HC's SDA and SCL pins to 20 and 21.

The PinMapping2560 page (http://arduino.cc/en/Hacking/PinMapping2560) says that the Mega's A4 and A5 pins are for TMK and TMS, but I can't find any information on what those functions are. If I plug the HC in as a shield and wire the pins as above, I'd also be wiring the Megas A4 to 20 and A5 to 21. Would that cause any damage on power-up?

2

It's a good thing I learned how to use the two boards separated!

Does anyone know what TMK and TMS are?

3

Just set the other pins as inputs, you will be fine.
TMK & TMS are used in JTAG if you have that enabled for debugging (needs fuse burning).

4

Good to know, thanks. I'm not using JTAG and I don't even need to use any analog pins in my project anyway so I guess not doing anything with them in my sketch means they're essentially disabled?

5

As long as you don't set them as outputs, they can be considered "disabled".

6

Awesome, thanks CrossRoads!