Tartan5
Member Since: March 24, 2009
Country: United States
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Question: If the absolute position counter is +/- 221, and I am set for 1/128 uStepping with a 200 steps/rev motor, then I can only turn the stepper +/- 81.92 revs from zero before losing my position???
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No, in the circuit above, replacing the resistor with a wire results in vcc being shorted to ground when the button is pressed, a very bad thing. In this case, it IS current limiting the current through the button AND providing a logic hi when not pressed.
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Not really. A current limiting resistor’s function is to limit the amount of current flowing into something, ie the resistor before an led limits the forward current through the led so you don’t burn it out. A pullup resistor is used (among other reasons) to provide a known state to an input. For example, if the resistor is eliminated from the above schematic, the input is known to be low (0 V) when the button is pressed, but the pin would be floating (not connected to any source) when the button is not pressed. If you read this input, you may get a 1, or you may get a 0, depending on noise coupling, etc. Note that some input pins can be configured internal to the device with a pullup…..
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