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 "shared-bindings/supervisor/__init__.h"
#include "supervisor/port.h"
#include "supervisor/shared/tick.h"

static void shiftregisterkeys_scan_now(void *self, mp_obj_t timestamp);
static size_t shiftregisterkeys_get_key_count(void *self);

static keypad_scanner_funcs_t shiftregisterkeys_funcs = {
    .scan_now = shiftregisterkeys_scan_now,
    .get_key_count = shiftregisterkeys_get_key_count,
};

void common_hal_keypad_shiftregisterkeys_construct(keypad_shiftregisterkeys_obj_t *self, const mcu_pin_obj_t *clock_pin, mp_uint_t num_data_pins, const mcu_pin_obj_t *data_pins[], const mcu_pin_obj_t *latch_pin, bool value_to_latch, mp_uint_t num_key_counts, size_t key_counts[], bool value_when_pressed, mp_float_t interval, size_t max_events) {

    digitalio_digitalinout_obj_t *clock =
        mp_obj_malloc(digitalio_digitalinout_obj_t, &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 *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;

    mp_obj_t dios[num_data_pins];

    for (size_t i = 0; i < num_data_pins; i++) {
        digitalio_digitalinout_obj_t *dio = m_new_obj(digitalio_digitalinout_obj_t);
        dio->base.type = &digitalio_digitalinout_type;
        common_hal_digitalio_digitalinout_construct(dio, data_pins[i]);
        common_hal_digitalio_digitalinout_switch_to_input(dio, PULL_NONE);
        dios[i] = dio;
    }

    // Allocate a tuple object with the data pins
    self->data_pins = mp_obj_new_tuple(num_data_pins, dios);

    self->key_counts = (mp_uint_t *)m_malloc(sizeof(mp_uint_t) * num_key_counts);
    self->num_key_counts = num_key_counts;

    // copy to an m_malloc() and on the fly record pin with largest Shift register
    mp_uint_t max = 0;

    for (mp_uint_t i = 0; i < self->num_key_counts; i++) {
        mp_uint_t cnt = key_counts[i];

        if (cnt > max) {
            max = cnt;
        }

        self->key_counts[i] = cnt;
    }

    self->max_key_count = max;

    self->value_to_latch = value_to_latch;
    self->value_when_pressed = value_when_pressed;
    self->funcs = &shiftregisterkeys_funcs;

    keypad_construct_common((keypad_scanner_obj_t *)self, interval, max_events);
}

void common_hal_keypad_shiftregisterkeys_deinit(keypad_shiftregisterkeys_obj_t *self) {
    if (common_hal_keypad_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->latch);
    self->latch = MP_ROM_NONE;

    for (size_t key = 0; key < self->data_pins->len; key++) {
        common_hal_digitalio_digitalinout_deinit(self->data_pins->items[key]);
    }
    self->data_pins = MP_ROM_NONE;
    self->key_counts = MP_ROM_NONE;

    common_hal_keypad_deinit_core(self);
}

size_t shiftregisterkeys_get_key_count(void *self_in) {
    keypad_shiftregisterkeys_obj_t *self = self_in;

    size_t total = 0;

    for (mp_uint_t i = 0; i < self->num_key_counts; i++) {
        total += self->key_counts[i];
    }

    return total;
}

static void shiftregisterkeys_scan_now(void *self_in, mp_obj_t timestamp) {
    keypad_shiftregisterkeys_obj_t *self = self_in;

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

    // Scan for max_key_count bit
    for (mp_uint_t scan_number = 0; scan_number < self->max_key_count; scan_number++) {
        common_hal_digitalio_digitalinout_set_value(self->clock, false);

        // Zero-th data appears on on the data pin immediately, without shifting.

        // Loop through all the data pins that share the latch
        mp_uint_t index = 0;

        for (mp_uint_t i = 0; i < self->data_pins->len; i++) {

            // When this data pin has less shiftable bits, ignore it
            if (scan_number >= self->key_counts[i]) {
                continue;
            }

            mp_uint_t key_number = scan_number + index;

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

            // Get the current state.
            const bool current =
                common_hal_digitalio_digitalinout_get_value(self->data_pins->items[i]) == self->value_when_pressed;
            self->currently_pressed[key_number] = current;

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

            index += self->key_counts[i];
        }

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

    }

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