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+/*
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+ * Copyright (c) 2019 David Antliff
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+ * Copyright 2011 Ben Buxton
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+ *
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+ * This file is part of the esp32-rotary-encoder component.
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+ *
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+ * esp32-rotary-encoder is free software: you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation, either version 3 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * esp32-rotary-encoder is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with esp32-rotary-encoder. If not, see <https://www.gnu.org/licenses/>.
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+ */
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+
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+/**
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+ * @file rotary_encoder.c
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+ * @brief Driver implementation for the ESP32-compatible Incremental Rotary Encoder component.
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+ *
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+ * Based on https://github.com/buxtronix/arduino/tree/master/libraries/Rotary
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+ * Original header follows:
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+ *
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+ * Rotary encoder handler for arduino. v1.1
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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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+ * A typical mechanical rotary encoder emits a two bit gray code
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+ * on 3 output pins. Every step in the output (often accompanied
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+ * by a physical 'click') generates a specific sequence of output
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+ * codes on the pins.
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+ *
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+ * There are 3 pins used for the rotary encoding - one common and
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+ * two 'bit' pins.
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+ *
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+ * The following is the typical sequence of code on the output when
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+ * moving from one step to the next:
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+ *
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+ * Position Bit1 Bit2
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+ * ----------------------
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+ * Step1 0 0
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+ * 1/4 1 0
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+ * 1/2 1 1
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+ * 3/4 0 1
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+ * Step2 0 0
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+ *
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+ * From this table, we can see that when moving from one 'click' to
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+ * the next, there are 4 changes in the output code.
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+ *
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+ * - From an initial 0 - 0, Bit1 goes high, Bit0 stays low.
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+ * - Then both bits are high, halfway through the step.
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+ * - Then Bit1 goes low, but Bit2 stays high.
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+ * - Finally at the end of the step, both bits return to 0.
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+ *
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+ * Detecting the direction is easy - the table simply goes in the other
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+ * direction (read up instead of down).
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+ *
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+ * To decode this, we use a simple state machine. Every time the output
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+ * code changes, it follows state, until finally a full steps worth of
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+ * code is received (in the correct order). At the final 0-0, it returns
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+ * a value indicating a step in one direction or the other.
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+ *
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+ * It's also possible to use 'half-step' mode. This just emits an event
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+ * at both the 0-0 and 1-1 positions. This might be useful for some
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+ * encoders where you want to detect all positions.
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+ *
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+ * If an invalid state happens (for example we go from '0-1' straight
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+ * to '1-0'), the state machine resets to the start until 0-0 and the
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+ * next valid codes occur.
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+ *
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+ * The biggest advantage of using a state machine over other algorithms
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+ * is that this has inherent debounce built in. Other algorithms emit spurious
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+ * output with switch bounce, but this one will simply flip between
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+ * sub-states until the bounce settles, then continue along the state
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+ * machine.
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+ * A side effect of debounce is that fast rotations can cause steps to
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+ * be skipped. By not requiring debounce, fast rotations can be accurately
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+ * measured.
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+ * Another advantage is the ability to properly handle bad state, such
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+ * as due to EMI, etc.
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+ * It is also a lot simpler than others - a static state table and less
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+ * than 10 lines of logic.
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+ */
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+
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+#include "rotary_encoder.h"
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+
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+#include "esp_log.h"
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+#include "driver/gpio.h"
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+
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+#define TAG "rotary_encoder"
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+
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+//#define ROTARY_ENCODER_DEBUG
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+
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+// Use a single-item queue so that the last value can be easily overwritten by the interrupt handler
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+#define EVENT_QUEUE_LENGTH 1
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+
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+#define TABLE_ROWS 7
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+
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+#define DIR_NONE 0x0 // No complete step yet.
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+#define DIR_CW 0x10 // Clockwise step.
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+#define DIR_CCW 0x20 // Anti-clockwise step.
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+
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+// Create the half-step state table (emits a code at 00 and 11)
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+#define R_START 0x0
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+#define H_CCW_BEGIN 0x1
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+#define H_CW_BEGIN 0x2
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+#define H_START_M 0x3
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+#define H_CW_BEGIN_M 0x4
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+#define H_CCW_BEGIN_M 0x5
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+
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+static const uint8_t _ttable_half[TABLE_ROWS][TABLE_COLS] = {
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+ // 00 01 10 11 // BA
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+ {H_START_M, H_CW_BEGIN, H_CCW_BEGIN, R_START}, // R_START (00)
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+ {H_START_M | DIR_CCW, R_START, H_CCW_BEGIN, R_START}, // H_CCW_BEGIN
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+ {H_START_M | DIR_CW, H_CW_BEGIN, R_START, R_START}, // H_CW_BEGIN
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+ {H_START_M, H_CCW_BEGIN_M, H_CW_BEGIN_M, R_START}, // H_START_M (11)
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+ {H_START_M, H_START_M, H_CW_BEGIN_M, R_START | DIR_CW}, // H_CW_BEGIN_M
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+ {H_START_M, H_CCW_BEGIN_M, H_START_M, R_START | DIR_CCW}, // H_CCW_BEGIN_M
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+};
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+
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+// Create the full-step state table (emits a code at 00 only)
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+# define F_CW_FINAL 0x1
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+# define F_CW_BEGIN 0x2
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+# define F_CW_NEXT 0x3
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+# define F_CCW_BEGIN 0x4
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+# define F_CCW_FINAL 0x5
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+# define F_CCW_NEXT 0x6
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+
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+static const uint8_t _ttable_full[TABLE_ROWS][TABLE_COLS] = {
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+ // 00 01 10 11 // BA
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+ {R_START, F_CW_BEGIN, F_CCW_BEGIN, R_START}, // R_START
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+ {F_CW_NEXT, R_START, F_CW_FINAL, R_START | DIR_CW}, // F_CW_FINAL
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+ {F_CW_NEXT, F_CW_BEGIN, R_START, R_START}, // F_CW_BEGIN
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+ {F_CW_NEXT, F_CW_BEGIN, F_CW_FINAL, R_START}, // F_CW_NEXT
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+ {F_CCW_NEXT, R_START, F_CCW_BEGIN, R_START}, // F_CCW_BEGIN
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+ {F_CCW_NEXT, F_CCW_FINAL, R_START, R_START | DIR_CCW}, // F_CCW_FINAL
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+ {F_CCW_NEXT, F_CCW_FINAL, F_CCW_BEGIN, R_START}, // F_CCW_NEXT
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+};
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+
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+static uint8_t _process(rotary_encoder_info_t * info)
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+{
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+ uint8_t event = 0;
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+ if (info != NULL)
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+ {
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+ // Get state of input pins.
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+ uint8_t pin_state = (gpio_get_level(info->pin_b) << 1) | gpio_get_level(info->pin_a);
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+
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+ // Determine new state from the pins and state table.
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+#ifdef ROTARY_ENCODER_DEBUG
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+ uint8_t old_state = info->table_state;
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+#endif
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+ info->table_state = info->table[info->table_state & 0xf][pin_state];
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+
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+ // Return emit bits, i.e. the generated event.
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+ event = info->table_state & 0x30;
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+#ifdef ROTARY_ENCODER_DEBUG
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+ ESP_EARLY_LOGD(TAG, "BA %d%d, state 0x%02x, new state 0x%02x, event 0x%02x",
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+ pin_state >> 1, pin_state & 1, old_state, info->table_state, event);
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+#endif
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+ }
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+ return event;
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+}
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+
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+static void _isr_rotenc(void * args)
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+{
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+ rotary_encoder_info_t * info = (rotary_encoder_info_t *)args;
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+ uint8_t event = _process(info);
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+ bool send_event = false;
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+
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+ switch (event)
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+ {
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+ case DIR_CW:
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+ ++info->state.position;
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+ info->state.direction = ROTARY_ENCODER_DIRECTION_CLOCKWISE;
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+ send_event = true;
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+ break;
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+ case DIR_CCW:
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+ --info->state.position;
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+ info->state.direction = ROTARY_ENCODER_DIRECTION_COUNTER_CLOCKWISE;
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+ send_event = true;
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+ break;
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+ default:
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+ break;
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+ }
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+
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+ if (send_event && info->queue)
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+ {
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+ rotary_encoder_event_t queue_event =
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+ {
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+ .state =
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+ {
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+ .position = info->state.position,
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+ .direction = info->state.direction,
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+ },
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+ };
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+ BaseType_t task_woken = pdFALSE;
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+ xQueueOverwriteFromISR(info->queue, &queue_event, &task_woken);
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+ if (task_woken)
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+ {
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+ portYIELD_FROM_ISR();
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+ }
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+ }
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+}
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+
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+esp_err_t rotary_encoder_init(rotary_encoder_info_t * info, gpio_num_t pin_a, gpio_num_t pin_b)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info)
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+ {
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+ info->pin_a = pin_a;
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+ info->pin_b = pin_b;
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+ info->table = &_ttable_full[0]; //enable_half_step ? &_ttable_half[0] : &_ttable_full[0];
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+ info->table_state = R_START;
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+ info->state.position = 0;
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+ info->state.direction = ROTARY_ENCODER_DIRECTION_NOT_SET;
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+
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+ // configure GPIOs
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+ gpio_pad_select_gpio(info->pin_a);
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+ gpio_set_pull_mode(info->pin_a, GPIO_PULLUP_ONLY);
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+ gpio_set_direction(info->pin_a, GPIO_MODE_INPUT);
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+ gpio_set_intr_type(info->pin_a, GPIO_INTR_ANYEDGE);
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+
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+ gpio_pad_select_gpio(info->pin_b);
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+ gpio_set_pull_mode(info->pin_b, GPIO_PULLUP_ONLY);
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+ gpio_set_direction(info->pin_b, GPIO_MODE_INPUT);
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+ gpio_set_intr_type(info->pin_b, GPIO_INTR_ANYEDGE);
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+
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+ // install interrupt handlers
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+ gpio_isr_handler_add(info->pin_a, _isr_rotenc, info);
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+ gpio_isr_handler_add(info->pin_b, _isr_rotenc, info);
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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+
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+esp_err_t rotary_encoder_enable_half_steps(rotary_encoder_info_t * info, bool enable)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info)
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+ {
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+ info->table = enable ? &_ttable_half[0] : &_ttable_full[0];
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+ info->table_state = R_START;
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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+
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+esp_err_t rotary_encoder_flip_direction(rotary_encoder_info_t * info)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info)
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+ {
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+ gpio_num_t temp = info->pin_a;
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+ info->pin_a = info->pin_b;
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+ info->pin_b = temp;
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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+
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+esp_err_t rotary_encoder_uninit(rotary_encoder_info_t * info)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info)
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+ {
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+ gpio_isr_handler_remove(info->pin_a);
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+ gpio_isr_handler_remove(info->pin_b);
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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+
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+QueueHandle_t rotary_encoder_create_queue(void)
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+{
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+ return xQueueCreate(EVENT_QUEUE_LENGTH, sizeof(rotary_encoder_event_t));
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+}
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+
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+esp_err_t rotary_encoder_set_queue(rotary_encoder_info_t * info, QueueHandle_t queue)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info)
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+ {
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+ info->queue = queue;
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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+
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+esp_err_t rotary_encoder_get_state(const rotary_encoder_info_t * info, rotary_encoder_state_t * state)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info && state)
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+ {
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+ // make a snapshot of the state
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+ state->position = info->state.position;
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+ state->direction = info->state.direction;
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info and/or state is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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+
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+esp_err_t rotary_encoder_reset(rotary_encoder_info_t * info)
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+{
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+ esp_err_t err = ESP_OK;
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+ if (info)
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+ {
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+ info->state.position = 0;
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+ info->state.direction = ROTARY_ENCODER_DIRECTION_NOT_SET;
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+ }
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+ else
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+ {
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+ ESP_LOGE(TAG, "info is NULL");
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+ err = ESP_ERR_INVALID_ARG;
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+ }
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+ return err;
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+}
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philippe44