I'm working on the thermistor-on-the-joystick-port trick that I discussed in another thread. What I'm trying to do is just put a thermistor on the X axis of the joystick port and read that.

When I put a real joystick on the port, my software reads the X axis correctly. But when I unplug the joystick and put the thermistor on the pins that would normally be the X axis potentiometer, the Windows API returns a "joystick is unplugged" error code when I call the function.

How does Windows decide whether a joystick is plugged in or not? Are there other pins I need to bridge or something?

(Note that this is an old-style 15-pin analog joystick port.)

Or maybe I'm putting the thermistor on the wrong pins, too. I'm using the X axis sense pin (pin 3) and the ground next to it (pin 4). Am I supposed to connect it to +5vdc and the X axis pin instead of ground and X axis?

I used to know this stuff by heart, once upon a time, when I'd build joysticks from scratch to make things like homemade steering wheel controllers. It's been so long since I've done it though.

Never mind, figured it out myself. (a) joystick sense is pins 1-3 for x, and pins 6-8 for y. That's +5v and the X sensor, and +5v and the Y sensor. (b) Need a value on both the X and the Y axes to keep Windows happy. Not enough to just have a value on X.