R.O.B.

R.O.B. (Robotic Operating Buddy) is a toy robot accessory for the Nintendo Entertainment System (NES). It was launched in July 1985 as the Family Computer Robot in Japan, and October 1985 as R.O.B. in North America. Its short lifespan yielded only two games in the Robot Series: Gyromite and Stack-Up.

The R.O.B. unit's height is 24 cm (9.6 in). It has a head movement range of a 45° horizontally centered tilt. The arm movement range is 240° left and right with five stopping points, 7 cm (2.75 in) up and down with six stopping points, and 7 cm (2.75 in) between hands when open. The unit has five accessory slots around the hexagonal base, numbered clockwise, starting at the rear-left from the robot's point of view; and notches on the hands allow for specialized parts to be attached for each game. The tinted filter can be optionally attached over the eyes like sunglasses, to compensate for bright televisions or sunlight. The unit is powered by four AA batteries.

- from wikipedia

The protocol consists of a series of flashes of light, one bit per vertical sync. It takes 13 vertical syncs (or possibly 14—if Z is 1, the following field must be 0. [1]) to send a command:

000101w1x1y1z

Ten commands are known to exist:

wxyz	command
0101	Up 2 steps
1100	Up 1 step
0010	Down 1 step
1101	Down 2 steps
0100	Turns the body left
1000	Turns the body right
0110	Close the arms
1010	Open the arms
1001	Turn the head LED on permanently
0001	Reset = turn LED off, open arms, seek rightmost/upmost, then go back to center.

The other six possible messages have no result.

Additionally, an endless stream of 25 or 30 Hz flashes will cause the LED to blink when R.O.B. sees light from the TV. This helps with aiming the head.

A dump of the firmware has been made here, and it has now been disassembled: R.O.B. Firmware

It is not known how wide R.O.B.'s field of view is, but the light sensor is that same as the Zapper's.

See also:

• Controlling R.O.B. with a microcontroller
• Nocash's EveryNES § R.O.B.