activate drill motor using input w/ pull up resist

I would like to turn on a drill motor (5A inrush, 1.3A continuous @ 12VDC) using an INPUT on the arduino.

I have no outputs left (the cat5 cable I'm using does not have any outputs left to use, so I want to make this happen when I send a trigger to ground)

I'm using analog inputs with pull up resistors and I want a safe way to open the flow of current to the drill motor w/o damaging the pin on the micro.

So how do I make a signal to ground close a switch? hexfet + relay? but it's 0V being applied when switch closes...

*note this is for a toy gattling gun to cause the barrel to spin when the trigger is sent low (otherwise there will have to be a seperate switch). and I do not want to send the drill motor powersupply to the trigger, because if the batter goes out, the input can't go high, and this can not be! do you plan to connect a signal to ground using an input? Any pin on the Arduino that is an input can also be an output (yes, even the analog pins).

I'm using an analog pin as an input in this case, and have enabled the pull-up resistor so that when the momentary switch is open, it sends 5V back to to the input, when it closes, it shorts to ground and sends back 0V. I want to make this turn on the gate to a hexfet or relay to switch the drill motor on (using it's own 12Vdc supply).

I have no free output pins available on my CAT5 sytle connection, so I must find a way to make this happen w/ the triggerPin when closed... otherwise I must have a seperate switch for the motor, which is not ideal at all.

Use a P channel FET to switch the motor. However, you will need to drive the gate of this with an NPN transistor (base to 1K to arduino input, emitter to ground, collector to FET gate and 4k7 resistor, other end of resistor to +12V) to both invert the signal and get it up to 12V from the 5V arduino output.

Had to draw that out, makes sense. I'll order some parts and give it a shot.