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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>I’m trying to understand and use a rotary encoder on an Arduino project and I have a simple demo circuit working with the encoder and output to the serial monitor. I see how the code is working but I can’t find documentation that confirms what I’m seeing. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The C code builds a two digit binary number that is used as a pointer to values in an array that is used to output either a 1 or -1 to indicate if the encoder is rotating clockwise or counterclockwise – all well and fine. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The variable used as a pointer is a type byte initially set to zero (byte state = 0) with a function called by an interrupt to build the two digit pointer. I looked it up and a byte can either hold 8 bits or a decimal value from 0 to 255. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The pointer works fine and prints out either a 1 or -1 on the serial monitor. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My question is, how does the code know that a binary 10 is not the number ten as the pointer or binary 11 is not the number eleven as the pointer instead of knowing it is the number 2 or 3 to be used as the pointer to pick out values in the following array? <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>int bump[] = {0,0,-1,1}; <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The output is like this: Serial.print(bump[state]),DEC); //state being the built pointer of either binary 10 or 11 for a value of either decimal 2 or 3, respectively. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks to C code by Budd Churchward on YouTube.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Input appreciated. Thanks!<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Dwight<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>