I, Robot
Robotics are all the rage, and those old high-tech toys you might have lying around are ideal candidates for the Frankenstein/Arduino treatment.
Robotics are all the rage, and those old high-tech toys you might have lying around are ideal candidates for the Frankenstein/Arduino treatment.
In the previous issue, I showed how to upgrade a Robosapien toy with an Arduino brain [1]. Just to quickly recap, I chose a Robosapien robot because it is a great toy to hack an Arduino into: It was wildly popular about 10 years ago and sold millions of units, so, even if you don't have one yourself, there are a lot of second-hand ones around, and you can find one in perfect working order on the cheap on eBay. The toy is easily pulled apart without damaging its components, and the information printed on its control board makes it easy to figure out which wire controls which part of the Robosapien. Best of all: It has a lots of potential for cool hacks.
Movement is a big part of Robosapien, so in the last installment you learned how to implement an H-bridge that lets you easily control both speed and direction of a DC motor (the Robosapien uses DC motors, like those on electric cars, not servos) and you got hold of some L293Ds – chips that give you two H-bridges, one per side.
However, I left off in issue 9 with the realization that, despite the Arduino's many good points, it falls short when you need to control a large number of motors, such as those that move Robosapien's [2] limbs. The Robosapien has seven motors and each must be spun forward and backward to walk, move his arms, and open and close his claws. That means each motor needs the input from two PWM pins. That's 14 pins.
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