Hall Effect Joystick

I,Robot was the first Atari game to use the Hall-effect joystick. The Hall effect joystick was supposed to be a more reliable replacement for the analog joystick found on Red Baron and Food Fight. It wasn't. The Hall effect stick is a direct replacement for an analog stick, it has the same output. I,Robot's schematics call for an analog stick, which suggest the hall stick was a late addition to I,Robot.

I dont think there are any I,Robots out there that didn't have problems with the joystick. The original Hall effect sticks used on I,Robot were very poorly designed. Atari later revised the design for use on Road Runner and Escape from the Planet of the Robot Monsters. The updated Hall effect stick is much more reliable than the original sticks so if you are having trouble keeping your original stick calibrated, I recommend sticking a newer rev stick in there..

	This is the stick used in I,Robot. The big problem you get with these sticks it that the hall effect sensors bend back away from the magnets after a while and the response gradually gets worse and worse. The only way to correct this it to open up the panel and bend the sensors until you get the proper output. The handle on these sticks can also be spun around, a feature I dont like.
	This is the newer version of the hall stick that came out on all games after I,Robot. It has 2 screws that hold the hall sensors against the magnets so they cannot be bent back. Also,the handle also does not spin, and a couple pots were added so the sensitivity can be adjusted without having to physically move the hall sensors.

Calibrating the Hall effect stick
Adjusting these sticks isn't too hard, there are 2 Hall sensors, one for the X axis and one for the Y Axis. Just move the sensors until they are parallel with the magnet. It should not be touching the magnet, but a tiny bit away from it. On the old sticks, the only way to know if the sensor is the right distance from the magnet is to put the game into joystick test and see how it works.

Adjusting the newer stick is much easier, just aligh the hall sensor parallel to the magnet, and then move the screw so it just touches the back of the sensor (NO pressure). The screw is there so the sensor wont bend back and become less sensitive. Enter test mode and adjust the pots with a small screwdriver until everything lines up.

	This is the joystick test mode in I,Robot. The idea behind this test is you move the joystick around the screen and adjust the joystick until the range will only fill the yellow box.
	This stick is somewhat misadjusted and needs to be calibrated. The joystick settings are saved and checked at game powerup. If the stick is not centered in the same position, the game will prompt you to center the stick and press fire to calibrate.