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40732dc Jan 1, 2013
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/* Rotary encoder handler for arduino.
*
* Copyright 2011 Ben Buxton. Licenced under the GNU GPL Version 3.
* Contact: bb@cactii.net
*
*/
#include "Arduino.h"
#include "Rotary.h"
/*
* The below state table has, for each state (row), the new state
* to set based on the next encoder output. From left to right in,
* the table, the encoder outputs are 00, 01, 10, 11, and the value
* in that position is the new state to set.
*/
#define R_START 0x0
#ifdef HALF_STEP
// Use the half-step state table (emits a code at 00 and 11)
#define R_CCW_BEGIN 0x1
#define R_CW_BEGIN 0x2
#define R_START_M 0x3
#define R_CW_BEGIN_M 0x4
#define R_CCW_BEGIN_M 0x5
const unsigned char ttable[6][4] = {
// R_START (00)
{R_START_M, R_CW_BEGIN, R_CCW_BEGIN, R_START},
// R_CCW_BEGIN
{R_START_M | DIR_CCW, R_START, R_CCW_BEGIN, R_START},
// R_CW_BEGIN
{R_START_M | DIR_CW, R_CW_BEGIN, R_START, R_START},
// R_START_M (11)
{R_START_M, R_CCW_BEGIN_M, R_CW_BEGIN_M, R_START},
// R_CW_BEGIN_M
{R_START_M, R_START_M, R_CW_BEGIN_M, R_START | DIR_CW},
// R_CCW_BEGIN_M
{R_START_M, R_CCW_BEGIN_M, R_START_M, R_START | DIR_CCW},
};
#else
// Use the full-step state table (emits a code at 00 only)
#define R_CW_FINAL 0x1
#define R_CW_BEGIN 0x2
#define R_CW_NEXT 0x3
#define R_CCW_BEGIN 0x4
#define R_CCW_FINAL 0x5
#define R_CCW_NEXT 0x6
const unsigned char ttable[7][4] = {
// R_START
{R_START, R_CW_BEGIN, R_CCW_BEGIN, R_START},
// R_CW_FINAL
{R_CW_NEXT, R_START, R_CW_FINAL, R_START | DIR_CW},
// R_CW_BEGIN
{R_CW_NEXT, R_CW_BEGIN, R_START, R_START},
// R_CW_NEXT
{R_CW_NEXT, R_CW_BEGIN, R_CW_FINAL, R_START},
// R_CCW_BEGIN
{R_CCW_NEXT, R_START, R_CCW_BEGIN, R_START},
// R_CCW_FINAL
{R_CCW_NEXT, R_CCW_FINAL, R_START, R_START | DIR_CCW},
// R_CCW_NEXT
{R_CCW_NEXT, R_CCW_FINAL, R_CCW_BEGIN, R_START},
};
#endif
/*
* Constructor. Each arg is the pin number for each encoder contact.
*/
Rotary::Rotary(char _pin1, char _pin2) {
// Assign variables.
pin1 = _pin1;
pin2 = _pin2;
// Set pins to input.
pinMode(pin1, INPUT);
pinMode(pin2, INPUT);
#ifdef ENABLE_PULLUPS
digitalWrite(pin1, HIGH);
digitalWrite(pin2, HIGH);
#endif
// Initialise state.
state = R_START;
}
unsigned char Rotary::process() {
// Grab state of input pins.
unsigned char pinstate = (digitalRead(pin2) << 1) | digitalRead(pin1);
// Determine new state from the pins and state table.
state = ttable[state & 0xf][pinstate];
// Return emit bits, ie the generated event.
return state & 0x30;
}