caesarCipher.c

/* Documentation:
 *    Assuming an Arduino Mega with the Adafruit Motor Shield and a
 *  stepper motor with a 1.8deg resolution connected to M1 and M2
 *  Your IDE should have the AFMotor library installed before compilation.
 *    This software manages the movement of a dial connected to a stepper motor,
 *  for use in the demonstration of a caesar cipher (see https://en.wikipedia.org/wiki/Caesar_cipher)
 *  How movement is calculated:
 *   Steps per revolution: (360/motorResolution) + optional stepOffset
 *   Steps to move: (stepsPerRevolution/dialSections) * shiftAmount
 *   Examples:
 *     Clock: dialSections = 4
 *     Alphabet: dialSections = 26
 *   Where:
 *   - motorResolution is the degree value the motor itself moves per
 *  step (usually written on the motor somewhere),
 *   - motorRPM is the desired speed of the motor, in revolutions/min,
 *   - motorPort is the port the stepper is connected (default 1 for outputs
 *  M1 and M2),
 *   - dialSections is the number of sections on the dial which have an
 *  equal width in degrees,
 *   - shiftAmount is the number of letters to shift the cipher by (e.g. the
 *  number of full letters to move the dial by.
 *   - stepOffset - If your motor has some sort of abnormalities, use this for
 *  fine-tuning.
 */
#include <AFMotor.h>
float motorResolution = 1.8;
int motorRPM = 20;
int motorPort = 1;
float dialSections = 26;
int shiftAmount = 1;

float stepOffset = 0;
float stepsPerRevolution = (360/motorResolution) + stepOffset;
AF_Stepper dial(stepsPerRevolution, motorPort);

void setup() {
  dial.setSpeed(motorRPM);
  moveDial(shiftAmount);
}

void loop() {}

int moveDial(int shift){
    dial.step((stepsPerRevolution/dialSections) * shift, FORWARD, SINGLE);
}