pbio/drv/button_gpio: Wait for release and delay on power down.

Fixes pybricks/support#2176

Author: laurensvalk

lib/pbio/drv/button/button.h

@@ -15,9 +15,15 @@
  */
 void pbdrv_button_init(void);
 
+/**
+ * De-initializes the low level button driver.
+ */
+void pbdrv_button_deinit(void);
+
 #else
 
 #define pbdrv_button_init()
+#define pbdrv_button_deinit()
 
 #endif
 

lib/pbio/drv/button/button_gpio.c

@@ -9,6 +9,7 @@
 
 #include <pbdrv/gpio.h>
 #include <pbio/button.h>
+#include <pbio/busy_count.h>
 #include <pbio/config.h>
 #include <pbio/error.h>
 #include <pbio/os.h>
@@ -49,7 +50,9 @@ pbio_error_t pbdrv_button_process_thread(pbio_os_state_t *state, void *context)
 
     pbio_os_timer_set(&timer, 10);
 
-    for (;;) {
+    // Loop until cancellation is requested on power off and buttons are released.
+    while (!pbdrv_button_process.request || pbdrv_button_state) {
+
         PBIO_OS_AWAIT_UNTIL(state, pbio_os_timer_is_expired(&timer));
 
         next = pbdrv_button_gpio_read();
@@ -64,8 +67,11 @@ pbio_error_t pbdrv_button_process_thread(pbio_os_state_t *state, void *context)
         pbio_os_timer_extend(&timer);
     }
 
-    // Unreachable
-    PBIO_OS_ASYNC_END(PBIO_ERROR_FAILED);
+    // Wait a while after release to prevent accidental power on.
+    PBIO_OS_AWAIT_MS(state, &timer, 100);
+    pbio_busy_count_down();
+
+    PBIO_OS_ASYNC_END(PBIO_ERROR_CANCELED);
 }
 
 #endif // PBDRV_CONFIG_BUTTON_GPIO_DEBOUNCE
@@ -90,4 +96,11 @@ void pbdrv_button_init(void) {
     #endif
 }
 
+void pbdrv_button_deinit(void) {
+    #if PBDRV_CONFIG_BUTTON_GPIO_DEBOUNCE
+    pbio_busy_count_up();
+    pbio_os_process_make_request(&pbdrv_button_process, PBIO_OS_PROCESS_REQUEST_TYPE_CANCEL);
+    #endif
+}
+
 #endif // PBDRV_CONFIG_BUTTON_GPIO

lib/pbio/drv/button/button_nxt.c

@@ -14,6 +14,9 @@
 void pbdrv_button_init(void) {
 }
 
+void pbdrv_button_deinit(void) {
+}
+
 pbio_button_flags_t pbdrv_button_get_pressed(void) {
 
     nx_avr_button_t button = nx_avr_get_button();

lib/pbio/drv/button/button_resistor_ladder.c

@@ -48,6 +48,9 @@ void pbdrv_button_init(void) {
     pbio_os_process_start(&pbdrv_button_init_process, pbdrv_button_init_process_thread, NULL);
 }
 
+void pbdrv_button_deinit(void) {
+}
+
 pbio_button_flags_t pbdrv_button_get_pressed(void) {
     pbdrv_resistor_ladder_ch_flags_t flags;
     pbio_error_t err;

lib/pbio/drv/button/button_test.c

@@ -19,6 +19,9 @@ void pbio_test_button_set_pressed(pbio_button_flags_t flags) {
 void pbdrv_button_init(void) {
 }
 
+void pbdrv_button_deinit(void) {
+}
+
 pbio_button_flags_t pbdrv_button_get_pressed(void) {
     return pbio_test_button_flags;
 }

lib/pbio/drv/core.c

@@ -89,6 +89,7 @@ void pbdrv_deinit(void) {
 
     pbdrv_imu_deinit();
     pbdrv_bluetooth_deinit();
+    pbdrv_button_deinit();
 
     while (pbio_busy_count_busy()) {
         pbio_os_run_processes_once();