circuitpython/ports/atmel-samd/common-hal/rotaryio/IncrementalEncoder.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "common-hal/rotaryio/IncrementalEncoder.h"
#include "atmel_start_pins.h"
#include "eic_handler.h"
#include "samd/external_interrupts.h"
#include "py/runtime.h"
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#include "supervisor/shared/translate.h"
void common_hal_rotaryio_incrementalencoder_construct(rotaryio_incrementalencoder_obj_t* self,
const mcu_pin_obj_t* pin_a, const mcu_pin_obj_t* pin_b) {
if (!pin_a->has_extint || !pin_a->has_extint) {
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mp_raise_RuntimeError(translate("Both pins must support hardware interrupts"));
}
// TODO: The SAMD51 has a peripheral dedicated to quadrature encoder debugging. Use it instead
// of the external interrupt.
if (eic_get_enable()) {
if (!eic_channel_free(pin_a->extint_channel) || !eic_channel_free(pin_b->extint_channel)) {
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mp_raise_RuntimeError(translate("A hardware interrupt channel is already in use"));
}
} else {
turn_on_external_interrupt_controller();
}
// These default settings apply when the EIC isn't yet enabled.
self->eic_channel_a = pin_a->extint_channel;
self->eic_channel_b = pin_b->extint_channel;
self->pin_a = pin_a->number;
self->pin_b = pin_b->number;
gpio_set_pin_function(self->pin_a, GPIO_PIN_FUNCTION_A);
gpio_set_pin_pull_mode(self->pin_a, GPIO_PULL_UP);
gpio_set_pin_function(self->pin_b, GPIO_PIN_FUNCTION_A);
gpio_set_pin_pull_mode(self->pin_b, GPIO_PULL_UP);
set_eic_channel_data(self->eic_channel_a, (void*) self);
set_eic_channel_data(self->eic_channel_b, (void*) self);
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self->position = 0;
self->quarter_count = 0;
// Top two bits of self->last_state don't matter, because they'll be gone as soon as
// interrupt handler is called.
self->last_state =
((uint8_t) gpio_get_pin_level(self->pin_a) << 1) |
(uint8_t) gpio_get_pin_level(self->pin_b);
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claim_pin(pin_a);
claim_pin(pin_b);
set_eic_handler(self->eic_channel_a, EIC_HANDLER_INCREMENTAL_ENCODER);
turn_on_eic_channel(self->eic_channel_a, EIC_CONFIG_SENSE0_BOTH_Val);
set_eic_handler(self->eic_channel_b, EIC_HANDLER_INCREMENTAL_ENCODER);
turn_on_eic_channel(self->eic_channel_b, EIC_CONFIG_SENSE0_BOTH_Val);
}
bool common_hal_rotaryio_incrementalencoder_deinited(rotaryio_incrementalencoder_obj_t* self) {
return self->pin_a == NO_PIN;
}
void common_hal_rotaryio_incrementalencoder_deinit(rotaryio_incrementalencoder_obj_t* self) {
if (common_hal_rotaryio_incrementalencoder_deinited(self)) {
return;
}
set_eic_handler(self->eic_channel_a, EIC_HANDLER_NO_INTERRUPT);
turn_off_eic_channel(self->eic_channel_a);
set_eic_handler(self->eic_channel_b, EIC_HANDLER_NO_INTERRUPT);
turn_off_eic_channel(self->eic_channel_b);
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reset_pin_number(self->pin_a);
self->pin_a = NO_PIN;
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reset_pin_number(self->pin_b);
self->pin_b = NO_PIN;
}
mp_int_t common_hal_rotaryio_incrementalencoder_get_position(rotaryio_incrementalencoder_obj_t* self) {
return self->position;
}
void common_hal_rotaryio_incrementalencoder_set_position(rotaryio_incrementalencoder_obj_t* self,
mp_int_t new_position) {
self->position = new_position;
}
void incrementalencoder_interrupt_handler(uint8_t channel) {
rotaryio_incrementalencoder_obj_t* self = get_eic_channel_data(channel);
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// This table also works for detent both at 11 and 00
// For 11 at detent:
// Turning cw: 11->01->00->10->11
// Turning ccw: 11->10->00->01->11
// For 00 at detent:
// Turning cw: 00->10->11->10->00
// Turning ccw: 00->01->11->10->00
// index table by state <oldA><oldB><newA><newB>
#define BAD 7
static const int8_t transitions[16] = {
0, // 00 -> 00 no movement
-1, // 00 -> 01 3/4 ccw (11 detent) or 1/4 ccw (00 at detent)
+1, // 00 -> 10 3/4 cw or 1/4 cw
BAD, // 00 -> 11 non-Gray-code transition
+1, // 01 -> 00 2/4 or 4/4 cw
0, // 01 -> 01 no movement
BAD, // 01 -> 10 non-Gray-code transition
-1, // 01 -> 11 4/4 or 2/4 ccw
-1, // 10 -> 00 2/4 or 4/4 ccw
BAD, // 10 -> 01 non-Gray-code transition
0, // 10 -> 10 no movement
+1, // 10 -> 11 4/4 or 2/4 cw
BAD, // 11 -> 00 non-Gray-code transition
+1, // 11 -> 01 1/4 or 3/4 cw
-1, // 11 -> 10 1/4 or 3/4 ccw
0, // 11 -> 11 no movement
};
// Shift the old AB bits to the "old" position, and set the new AB bits.
// TODO(tannewt): If we need more speed then read the pin directly. gpio_get_pin_level has
// smarts to compensate for pin direction we don't need.
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self->last_state = (self->last_state & 0x3) << 2 |
((uint8_t) gpio_get_pin_level(self->pin_a) << 1) |
(uint8_t) gpio_get_pin_level(self->pin_b);
int8_t quarter_incr = transitions[self->last_state];
if (quarter_incr == BAD) {
// Missed a transition. We don't know which way we're going, so do nothing.
return;
}
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self->quarter_count += quarter_incr;
if (self->quarter_count >= 4) {
self->position += 1;
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self->quarter_count = 0;
} else if (self->quarter_count <= -4) {
self->position -= 1;
self->quarter_count = 0;
}
}