circuitpython/shared-module/keypad/ShiftRegisterKeys.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2021 Dan Halbert 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 <string.h>

#include "py/gc.h"
#include "py/runtime.h"
#include "shared-bindings/digitalio/DigitalInOut.h"
#include "shared-bindings/keypad/EventQueue.h"
#include "shared-bindings/keypad/ShiftRegisterKeys.h"
#include "shared-bindings/keypad/__init__.h"
#include "supervisor/port.h"
#include "supervisor/shared/tick.h"

#define DEBOUNCE_TICKS (20)

void common_hal_keypad_shiftregisterkeys_construct(keypad_shiftregisterkeys_obj_t *self, mcu_pin_obj_t *clock_pin, mcu_pin_obj_t *data_pin, mcu_pin_obj_t *latch_pin, size_t num_keys, bool value_when_pressed, size_t max_events) {

    digitalio_digitalinout_obj_t *clock = m_new_obj(digitalio_digitalinout_obj_t);
    clock->base.type = &digitalio_digitalinout_type;
    common_hal_digitalio_digitalinout_construct(clock, clock_pin);
    common_hal_digitalio_digitalinout_switch_to_output(clock, false, DRIVE_MODE_PUSH_PULL);
    self->clock = clock;

    digitalio_digitalinout_obj_t *data = m_new_obj(digitalio_digitalinout_obj_t);
    data->base.type = &digitalio_digitalinout_type;
    common_hal_digitalio_digitalinout_construct(data, data_pin);
    common_hal_digitalio_digitalinout_switch_to_input(data, PULL_NONE);
    self->data = data;

    digitalio_digitalinout_obj_t *latch = m_new_obj(digitalio_digitalinout_obj_t);
    latch->base.type = &digitalio_digitalinout_type;
    common_hal_digitalio_digitalinout_construct(latch, latch_pin);
    common_hal_digitalio_digitalinout_switch_to_output(latch, true, DRIVE_MODE_PUSH_PULL);
    self->latch = latch;

    self->currently_pressed = (bool *)gc_alloc(sizeof(bool) * num_keys, false, false);
    self->previously_pressed = (bool *)gc_alloc(sizeof(bool) * num_keys, false, false);
    self->value_when_pressed = value_when_pressed;
    self->num_keys = num_keys;

    self->last_scan_ticks = port_get_raw_ticks(NULL);

    keypad_eventqueue_obj_t *events = m_new_obj(keypad_eventqueue_obj_t);
    events->base.type = &keypad_eventqueue_type;
    common_hal_keypad_eventqueue_construct(events, max_events);
    self->events = events;

    // Add self to the list of active keypad scanners.
    keypad_register_scanner((keypad_scanner_obj_t *)self);

    supervisor_enable_tick();
}

void common_hal_keypad_shiftregisterkeys_deinit(keypad_shiftregisterkeys_obj_t *self) {
    if (common_hal_keypad_shiftregisterkeys_deinited(self)) {
        return;
    }

    // Remove self from the list of active keypad scanners first.
    keypad_deregister_scanner((keypad_scanner_obj_t *)self);


    common_hal_digitalio_digitalinout_deinit(self->clock);
    self->clock = MP_ROM_NONE;

    common_hal_digitalio_digitalinout_deinit(self->data);
    self->data = MP_ROM_NONE;

    common_hal_digitalio_digitalinout_deinit(self->latch);
    self->latch = MP_ROM_NONE;
}

bool common_hal_keypad_shiftregisterkeys_deinited(keypad_shiftregisterkeys_obj_t *self) {
    return self->clock == MP_ROM_NONE;
}

size_t common_hal_keypad_shiftregisterkeys_get_num_keys(keypad_shiftregisterkeys_obj_t *self) {
    return self->num_keys;
}
bool common_hal_keypad_shiftregisterkeys_pressed(keypad_shiftregisterkeys_obj_t *self, mp_uint_t key_num) {
    return self->currently_pressed[key_num];
}

// The length of states has already been validated.
void common_hal_keypad_shiftregisterkeys_store_states(keypad_shiftregisterkeys_obj_t *self, uint8_t *states) {
    // Read the state atomically.
    supervisor_acquire_lock(&keypad_scanners_linked_list_lock);
    memcpy(states, self->currently_pressed, common_hal_keypad_shiftregisterkeys_get_num_keys(self));
    supervisor_release_lock(&keypad_scanners_linked_list_lock);
}

mp_obj_t common_hal_keypad_shiftregisterkeys_get_events(keypad_shiftregisterkeys_obj_t *self) {
    return MP_OBJ_FROM_PTR(self->events);
}

void keypad_shiftregisterkeys_scan(keypad_shiftregisterkeys_obj_t *self) {
    uint64_t now = port_get_raw_ticks(NULL);
    if (now - self->last_scan_ticks < DEBOUNCE_TICKS) {
        // Too soon. Wait longer to debounce.
        return;
    }

    self->last_scan_ticks = now;

    // Latch (freeze) the current state of the input pins.
    common_hal_digitalio_digitalinout_set_value(self->latch, true);

    for (mp_uint_t key_num = 0; key_num < common_hal_keypad_shiftregisterkeys_get_num_keys(self); key_num++) {
        // Zero-th data appears on on the data pin immediately, without shifting.
        common_hal_digitalio_digitalinout_set_value(self->clock, false);

        // Remember the previous up/down state.
        const bool previous = self->currently_pressed[key_num];
        self->previously_pressed[key_num] = previous;

        // Get the current state.
        const bool current =
            common_hal_digitalio_digitalinout_get_value(self->data) == self->value_when_pressed;
        self->currently_pressed[key_num] = current;

        // Trigger a shift to get the next bit.
        common_hal_digitalio_digitalinout_set_value(self->clock, true);

        // Record any transitions.
        if (previous != current) {
            keypad_eventqueue_record(self->events, key_num, current);
        }
    }

    // Start reading the input pins again.
    common_hal_digitalio_digitalinout_set_value(self->latch, false);

}