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Diffstat (limited to 'keyboards/ploopyco/common/opt_encoder_tiny.c')
-rw-r--r-- | keyboards/ploopyco/common/opt_encoder_tiny.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/keyboards/ploopyco/common/opt_encoder_tiny.c b/keyboards/ploopyco/common/opt_encoder_tiny.c new file mode 100644 index 0000000000..29796a5fa6 --- /dev/null +++ b/keyboards/ploopyco/common/opt_encoder_tiny.c @@ -0,0 +1,116 @@ +/* Copyright 2023 Leorize <[email protected]> + * Copyright 2011 Ben Buxton <[email protected]> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include "opt_encoder.h" +#include <stdbool.h> +#include <stdint.h> + +/* An extremely simple implementation of the encoder: + * + * For read out, the mechanism mimics that of a Schmitt trigger, with + * statically defined high/low thresholds used instead of computing + * one at runtime. + * + * The advantage of this approach is computing less in the decoder + * implementation and allow the state to be measured before the wheel + * moved. + * + * Compared to opt_encoder_simple.c, the use of an intermediary state + * reduces sensitivity and de-sensitize against tiny movements caused + * when lifting finger off the wheel. + * + * For turning decoded values into rotation, an algorithm inspired by + * http://www.buxtronix.net/2011/10/rotary-encoders-done-properly.html + * is employed. + */ + +#if !defined(ENCODER_LOW_THRES_A) || !defined(ENCODER_HIGH_THRES_A) +# error "The thresholds for phototransistors A is not defined in config.h" +#endif +#if !defined(ENCODER_LOW_THRES_B) || !defined(ENCODER_HIGH_THRES_B) +# error "The thresholds for phototransistors B is not defined in config.h" +#endif +/* + * Sample values, captured for a Ploopy Mini Trackball + * + * The following min-max values was captured by aggregating data recorded + * when debug_encoder is enabled: + * + * A: min: 0, max: 214 + * B: min: 0, max: 204 + * + * The threshold specified is then defined at the 1/4 and the 3/4 points. + * + * As these values might vary between units, you're encouraged to + * measure your own. + */ +#if 0 +# define ENCODER_LOW_THRES_A 53 +# define ENCODER_HIGH_THRES_A 161 +# define ENCODER_LOW_THRES_B 52 +# define ENCODER_HIGH_THRES_B 153 +#endif + +/* Utilities for composing the encoder state */ +#define MAKE_STATE(HI_A, HI_B) (((uint8_t)((HI_A) & 0x1) << 1) | ((uint8_t)((HI_B) & 0x1))) +#define STATE_A(st) ((st & 0x2) >> 1) +#define STATE_B(st) (st & 0x1) + +typedef enum { + START, + DOWN_BEGIN, + UP_BEGIN, + START_MID, + DOWN_BEGIN_MID, + UP_BEGIN_MID, + STATE_MASK = 0xf, /* 0b1111 */ + EMIT_UP = 0x10, + EMIT_UP_MID = EMIT_UP & START_MID, + EMIT_DOWN = 0x80, + EMIT_DOWN_MID = EMIT_DOWN & START_MID, + EMIT_MASK = 0xf0 +} encoder_state_t; + +static encoder_state_t state; +static uint8_t encState; + +static const uint8_t transitions[] = { + // clang-format off + // START -> 00, 01, 10, 11 + START, DOWN_BEGIN, UP_BEGIN, START_MID, + // DOWN_BEGIN -> 00, 01, 10, 11 + START, DOWN_BEGIN, START, EMIT_DOWN_MID, + // UP_BEGIN -> 00, 01, 10, 11 + START, START, UP_BEGIN, EMIT_UP_MID, + // START_MID -> 00, 01, 10, 11 + START, UP_BEGIN_MID, DOWN_BEGIN_MID, START_MID, + // DOWN_BEGIN_MID -> 00, 01, 10, 11 + EMIT_DOWN, START_MID, DOWN_BEGIN_MID, START_MID, + // UP_BEGIN_MID -> 00, 01, 10, 11 + EMIT_UP, UP_BEGIN_MID, START_MID, START_MID, + // clang-format on +}; + +void opt_encoder_init(void) { + state = START; + encState = 0; +} + +int8_t opt_encoder_handler(uint16_t encA, uint16_t encB) { + encState = MAKE_STATE((STATE_A(encState) & (encA > ENCODER_LOW_THRES_A)) | (encA > ENCODER_HIGH_THRES_A), (STATE_B(encState) & (encB > ENCODER_LOW_THRES_B)) | (encB > ENCODER_HIGH_THRES_B)); + state = transitions[((state & STATE_MASK) << 2) + encState]; + return state & EMIT_MASK; +} |