1 files changed, 134 insertions, 0 deletions
diff --git a/circuitpython/shared-module/keypad/ShiftRegisterKeys.c b/circuitpython/shared-module/keypad/ShiftRegisterKeys.c
new file mode 100644
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+++ b/circuitpython/shared-module/keypad/ShiftRegisterKeys.c
@@ -0,0 +1,134 @@
+/*
+ * 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, const mcu_pin_obj_t *data_pin, const mcu_pin_obj_t *latch_pin, bool value_to_latch, size_t key_count, bool value_when_pressed, mp_float_t interval, 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->value_to_latch = value_to_latch;
+
+    self->value_when_pressed = value_when_pressed;
+    self->key_count = key_count;
+    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->data);
+    self->data = MP_ROM_NONE;
+
+    common_hal_digitalio_digitalinout_deinit(self->latch);
+    self->latch = 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;
+    return self->key_count;
+}
+
+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);
+
+    const size_t key_count = shiftregisterkeys_get_key_count(self);
+
+    for (mp_uint_t key_number = 0; key_number < key_count; key_number++) {
+        // 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_number];
+        self->previously_pressed[key_number] = previous;
+
+        // Get the current state.
+        const bool current =
+            common_hal_digitalio_digitalinout_get_value(self->data) == self->value_when_pressed;
+        self->currently_pressed[key_number] = 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_number, current, timestamp);
+        }
+    }
+
+    // Start reading the input pins again.
+    common_hal_digitalio_digitalinout_set_value(self->latch, !self->value_to_latch);
+}