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Chapter 7. Project 1: Coat Hanger Walker > Freeforming the Bicore Control Circu...

Freeforming the Bicore Control Circuit

The first thing we’ll want to do in building our robot is to assemble its brain. The Coat Hanger Walker makes use of the ingenious BEAM Bicore circuit. It’s prefixed bi because it has two states, or nodes, and core because, well, it’s the central part of the robot’s nervous net. Our Bicore uses the 74HCT240 integrated circuit. This chip is an inverting octal buffer. That’s just a fancy way of saying that it is a chip with eight logic gates that invert the signals going into them. Whatever goes in each gate gets inverted, so a low signal becomes a high signal and a high signal becomes a low one. By combing the three gates on one side and three gates on the other (by soldering their pins together), we end up with two “teams” inverting gates that “buffer” the signal and make it more powerful. Bicore! The signal passing back and forth between the two nodes sends high and low (or “on” and “off”) pulses to our servo motor. The result is back and forth movement of the motor shaft, which is transferred to our gears to create a reciprocating walking motion. By the way, if you’re wondering, the remaining two gates are used as sort of the controller for the two three-gate teams.

Tip

If you’re unsure about any of these tools or what they do, refer back to Chapter 5.



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