1. Yes. 2K on the TIP120 will be OK.
2. There are a few ways/places you can add them.
The easiest way is simply to add a 12/24v capable switch after the TIP120. The switch would go from TIP120 collector to TIP120 emitter and basically bypasses the TIP120.
You can also look at the circuit for the breadboard version. This has the switch on the otherside of the TIP120. http://www.dropcontroller.com/build-guide-dropcontrollerbt-on-a-breadboard/
3. Use a BT module that has a STATE pin (normally HC-05). Wire the STATE pin to a LED + Resistor(100 ohm – 220 ohm) to GND. The STATE pin goes HIGH when a connection is made.
4. The next version of the sketch will handle both Bluetooth and USB automatically.
- This reply was modified 3 years ago by Martyn.