Chapter 12. Beyond LEGO Motors
The NXT has three output ports with variable power and polarity control that you can use to activate a variety of devices above and beyond LEGO motors. (The sophisticated pulse width modulation circuitry behind these ports was already described in Chapter 3.) The NXT output power is on the same two wires that we used for passive sensors: the black and the white wires in the NXT cable, or pin 1 and pin 2 on the output port connector. The white wire will be positive, and the black will be negative, when the motor output is set to forward. For most of the projects that follow, we'll show only 18 gauge (0.8mm2) speaker wires, and you can presume that they are attached to these two NXT connections.
The Motor Block