103 lines
2.8 KiB
C++
103 lines
2.8 KiB
C++
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/* Rotary encoder handler for arduino.
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*
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* Copyright 2011 Ben Buxton. Licenced under the GNU GPL Version 3.
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* Contact: bb@cactii.net
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*
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*/
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#include "Arduino.h"
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#include "Rotary.h"
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/*
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* The below state table has, for each state (row), the new state
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* to set based on the next encoder output. From left to right in,
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* the table, the encoder outputs are 00, 01, 10, 11, and the value
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* in that position is the new state to set.
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*/
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#define R_START 0x0
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#ifdef HALF_STEP
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// Use the half-step state table (emits a code at 00 and 11)
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#define R_CCW_BEGIN 0x1
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#define R_CW_BEGIN 0x2
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#define R_START_M 0x3
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#define R_CW_BEGIN_M 0x4
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#define R_CCW_BEGIN_M 0x5
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const unsigned char ttable[6][4] = {
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// R_START (00)
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{R_START_M, R_CW_BEGIN, R_CCW_BEGIN, R_START},
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// R_CCW_BEGIN
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{R_START_M | DIR_CCW, R_START, R_CCW_BEGIN, R_START},
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// R_CW_BEGIN
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{R_START_M | DIR_CW, R_CW_BEGIN, R_START, R_START},
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// R_START_M (11)
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{R_START_M, R_CCW_BEGIN_M, R_CW_BEGIN_M, R_START},
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// R_CW_BEGIN_M
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{R_START_M, R_START_M, R_CW_BEGIN_M, R_START | DIR_CW},
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// R_CCW_BEGIN_M
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{R_START_M, R_CCW_BEGIN_M, R_START_M, R_START | DIR_CCW},
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};
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#else
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// Use the full-step state table (emits a code at 00 only)
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#define R_CW_FINAL 0x1
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#define R_CW_BEGIN 0x2
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#define R_CW_NEXT 0x3
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#define R_CCW_BEGIN 0x4
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#define R_CCW_FINAL 0x5
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#define R_CCW_NEXT 0x6
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const unsigned char ttable[7][4] = {
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// R_START
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{R_START, R_CW_BEGIN, R_CCW_BEGIN, R_START},
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// R_CW_FINAL
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{R_CW_NEXT, R_START, R_CW_FINAL, R_START | DIR_CW},
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// R_CW_BEGIN
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{R_CW_NEXT, R_CW_BEGIN, R_START, R_START},
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// R_CW_NEXT
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{R_CW_NEXT, R_CW_BEGIN, R_CW_FINAL, R_START},
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// R_CCW_BEGIN
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{R_CCW_NEXT, R_START, R_CCW_BEGIN, R_START},
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// R_CCW_FINAL
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{R_CCW_NEXT, R_CCW_FINAL, R_START, R_START | DIR_CCW},
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// R_CCW_NEXT
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{R_CCW_NEXT, R_CCW_FINAL, R_CCW_BEGIN, R_START},
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};
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#endif
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/*
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* Constructor. Each arg is the pin number for each encoder contact.
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*/
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Rotary::Rotary(char _pin1, char _pin2) {
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// Assign variables.
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pin1 = _pin1;
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pin2 = _pin2;
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// Initialise state.
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state = R_START;
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// Don't invert read pin state by default
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inverter = 0;
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}
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void Rotary::begin(bool internalPullup, bool flipLogicForPulldown) {
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if (internalPullup){
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// Enable weak pullups
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pinMode(pin1,INPUT_PULLUP);
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pinMode(pin2,INPUT_PULLUP);
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}else{
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// Set pins to input.
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pinMode(pin1, INPUT);
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pinMode(pin2, INPUT);
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}
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inverter = flipLogicForPulldown ? 1 : 0;
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}
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unsigned char Rotary::process() {
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// Grab state of input pins.
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unsigned char pinstate = ((inverter ^ digitalRead(pin2)) << 1) | (inverter ^ digitalRead(pin1));
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// Determine new state from the pins and state table.
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state = ttable[state & 0xf][pinstate];
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// Return emit bits, ie the generated event.
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return state & 0x30;
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}
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