feature(Debounce):

Modified Debounce to compare with state in timeframe

lab_3/CMakeLists.txt

@@ -7,7 +7,6 @@ set(CMAKE_CXX_STANDARD 17)
 
 # Initialise pico_sdk from installed location
 # (note this can come from environment, CMake cache etc)
-set(PICO_SDK_PATH "/home/junwei/Documents/pico/pico-sdk")
 
 set(PICO_BOARD pico_w CACHE STRING "Board type")
 

lab_3/lab_3.c

@@ -20,13 +20,21 @@
 #include "hardware/gpio.h"
 
 #define PSEUDO_BTN  15          // GPIO 15 is the pseudo-button
-#define DELAY_US    1000000     // 1-second delay for repeating timer
-#define DEBOUNCE_US 100          // 100us debounce delay
+#define TIMER_US    1000000     // 1-second delay for repeating timer
+#define DEBOUNCE_US 100         // 100us debounce time
 
-u_int64_t time = 0;             // Elapsed time
-u_int prev_state = 0;           // Previous state of pseudo-button
 struct repeating_timer timer;   // Repeating timer
+u_int64_t time = 0;             // Elapsed time
 
+typedef enum btn_state {        // Button state
+    PRESSED = 0,
+    RELEASED = 1
+} btn_state_t;
+
+struct btn_status {             // Button status
+    uint btn_pressed;
+    uint btn_released;
+} btn_status = {0, 0};
 
 /**
  * Callback function for repeating timer
@@ -43,15 +51,32 @@ bool elapsed_time_callback (struct repeating_timer *t) {
 }
 
 /**
- * Debounce callback function to check if the current state
- * is equal to the previous state.
- * @param id         The alarm ID
- * @param new_event  The previous state of the pseudo-button
- * @return           True if the current state is equal to the previous state
+ * Get the state of the pseudo-button (pull-up)
+ * This function will implement a debounce algorithm to
+ * get the state of the pseudo-button. (With added complexity)
+ * @return The state of the pseudo-button
  */
-int64_t debounce_callback(alarm_id_t id, void *new_event) {
-    printf("Debounce Callback\n");
-    return (prev_state == *(uint32_t *)new_event);
+btn_state_t get_btn_state () {
+    u_int64_t start_time = time_us_64();
+    while (time_us_64() - start_time < DEBOUNCE_US)
+    {
+        if (gpio_get(PSEUDO_BTN))
+        {
+            btn_status.btn_released += 1;
+        }
+        else
+        {
+            btn_status.btn_pressed += 1;
+        }
+    }
+
+    btn_state_t state = (btn_status.btn_pressed > btn_status.btn_released) ?
+                           PRESSED : RELEASED;
+
+    btn_status.btn_pressed = 0;
+    btn_status.btn_released = 0;
+
+    return state;
 }
 
 /**
@@ -62,33 +87,24 @@ int64_t debounce_callback(alarm_id_t id, void *new_event) {
  * @param events    The type of interrupt that triggered the callback
  */
 void gpio_callback (uint gpio, uint32_t events) {
-    // Debounce algorithm
-    prev_state = prev_state == 0 ? events : prev_state;
+    btn_state_t btn_state = get_btn_state();
 
-    // Create an alarm that will trigger after 10ms
-    add_alarm_in_us(
-            DEBOUNCE_US,
-            debounce_callback,
-            &events,
-            false
-            );
-
-    // Start timer on button press
-    if (gpio == PSEUDO_BTN && events == GPIO_IRQ_EDGE_FALL)
+    if (events == GPIO_IRQ_EDGE_FALL && btn_state == PRESSED)
     {
         printf("\n====================================\n");
         printf("Timer Started\n");
         printf("====================================\n");
 
         add_repeating_timer_us(
-                DELAY_US,
+                TIMER_US,
                 elapsed_time_callback,
                 NULL,
                 &timer
         );
+
     }
-    // Stop timer on button release
-    if (gpio == PSEUDO_BTN && events == GPIO_IRQ_EDGE_RISE)
+
+    if (events == GPIO_IRQ_EDGE_RISE && btn_state == RELEASED)
     {
         cancel_repeating_timer(&timer);
 
@@ -100,6 +116,7 @@ void gpio_callback (uint gpio, uint32_t events) {
         printf("====================================\n");
 
         time = 0;
+
     }
 }