add debouncing

shared-bindings/keypad/Keys.c

@@ -80,20 +80,25 @@ STATIC mp_obj_t keypad_keys_make_new(const mp_obj_type_t *type, size_t n_args, c
     }
 
     common_hal_keypad_keys_construct(self, num_pins, pins_array, value_when_pressed, args[ARG_pull].u_bool);
+    common_hal_keypad_keys_scan(self);
     return MP_OBJ_FROM_PTR(self);
 }
 
-//|     def scan(self) -> None:
+//|     def scan(self) -> bool:
 //|         """Scan the keys and record which are newly pressed, still pressed,
-//|         newly released, and still released. For convenient activity checking,
+//|         newly released, and still released. If not enough time has elapsed since
+//|         the last scan for debouncing, do nothing and return ``False``.
+//|
+//|         :return: ``True`` if sufficient time has elapsed for debouncing (about 20 msecs),
+//|           otherwise ``False``.
+//|         :rtype: bool
 //|         """
 //|         ...
 //|
 STATIC mp_obj_t keypad_keys_scan(mp_obj_t self_in) {
     keypad_keys_obj_t *self = MP_OBJ_TO_PTR(self_in);
 
-    common_hal_keypad_keys_scan(self);
-    return MP_ROM_NONE;
+    return mp_obj_new_bool(common_hal_keypad_keys_scan(self));
 }
 MP_DEFINE_CONST_FUN_OBJ_1(keypad_keys_scan_obj, keypad_keys_scan);
 

shared-bindings/keypad/Keys.h

@@ -35,7 +35,7 @@ extern const mp_obj_type_t keypad_keys_type;
 void common_hal_keypad_keys_construct(keypad_keys_obj_t *self, mp_uint_t num_pins, mcu_pin_obj_t *pins[], bool value_when_pressed,  bool pull);
 void common_hal_keypad_keys_keys_with_state(keypad_keys_obj_t *self, mp_int_t state, mp_obj_list_t *into);
 size_t common_hal_keypad_keys_length(keypad_keys_obj_t *self);
-void common_hal_keypad_keys_scan(keypad_keys_obj_t *self);
+bool common_hal_keypad_keys_scan(keypad_keys_obj_t *self);
 mp_int_t common_hal_keypad_keys_state(keypad_keys_obj_t *self, mp_uint_t key_num);
 
 #endif  // MICROPY_INCLUDED_SHARED_BINDINGS_KEYPAD_KEYS_H

shared-module/keypad/Keys.c

@@ -30,6 +30,9 @@
 #include "shared-bindings/keypad/State.h"
 #include "shared-bindings/digitalio/DigitalInOut.h"
 #include "py/runtime.h"
+#include "supervisor/port.h"
+
+#define DEBOUNCE_TICKS (20)
 
 void common_hal_keypad_keys_construct(keypad_keys_obj_t *self, mp_uint_t num_pins, mcu_pin_obj_t *pins[], bool value_when_pressed, bool pull) {
     mp_obj_t dios[num_pins];
@@ -101,13 +104,22 @@ size_t common_hal_keypad_keys_length(keypad_keys_obj_t *self) {
     return self->digitalinouts->len;
 }
 
-void common_hal_keypad_keys_scan(keypad_keys_obj_t *self) {
+bool common_hal_keypad_keys_scan(keypad_keys_obj_t *self) {
+    uint64_t now = port_get_raw_ticks(NULL);
+    uint64_t last_scan_ticks = self->last_scan_ticks;
+    self->last_scan_ticks = now;
+    if (now - last_scan_ticks < DEBOUNCE_TICKS) {
+        // Too soon.
+        return false;
+    }
+
     for (mp_uint_t key_num = 0; key_num < common_hal_keypad_keys_length(self); key_num++) {
         self->previously_pressed[key_num] = self->currently_pressed[key_num];
         self->currently_pressed[key_num] =
             common_hal_digitalio_digitalinout_get_value(self->digitalinouts->items[key_num]) ==
             self->value_when_pressed;
     }
+    return true;
 }
 
 mp_int_t common_hal_keypad_keys_state(keypad_keys_obj_t *self, mp_uint_t key_num) {

shared-module/keypad/Keys.h

@@ -35,6 +35,7 @@
 typedef struct {
     mp_obj_base_t base;
     mp_obj_tuple_t *digitalinouts;
+    uint64_t last_scan_ticks;
     bool value_when_pressed;
     bool *previously_pressed;
     bool *currently_pressed;