Question:

Why do I need a resistor when I am using inputs or outputs on a Dobot Magician? For that matter, Do I need them for micro-controllers like the VEX, or Arduinos?

Answer:

Well… Yes; on the Dobot you may, and on some micro-controllers also. The reason for this is actually pretty simple, and can best be explained by watching the video below. This also explains why sometimes “ON” is “OFF” and “OFF is “ON”! A weird but true fact in some instances; just roll with. These resistors are either pull-up or pull-down resistors and make it so that the voltage on an input pin is either high or low… not floating somewhere in between. This is bad because in a digital system there are only two values: “ON” or “OFF”, and if you’re somewhere in between an input may go high or low spontaneously when you least expect it!

If you are having errors or erratic behaviors with an input pin on a micro-controller, or a robot, watch the video below for a good explanation why. This is also why you will see resistors used in the handshake modules we build and use as well as in all of our Dobot Activities.

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