pbio/drv/bluetooth_btstack: Make scan, connect, and pairing more robust.

CHANGELOG.md

@@ -33,7 +33,9 @@
 - Fixed Powered Up remote and Xbox Controller working only after the first
   connection. All of the above Remote and Xbox Controller were introduced in
   the previous beta release, so did not affect any stable release ([support#2521]).
+- Fixed Xbox Controller sometimes not working the first time ([support#1509]).
 
+[support#1509]: https://github.com/pybricks/support/issues/1509
 [support#1962]: https://github.com/pybricks/support/issues/1962
 [support#2468]: https://github.com/pybricks/support/issues/2468
 [support#2497]: https://github.com/pybricks/support/issues/2497

lib/pbio/drv/bluetooth/bluetooth.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2018-2025 The Pybricks Authors
+// Copyright (c) 2018-2026 The Pybricks Authors
 
 // Common Bluetooth driver code
 
@@ -195,15 +195,19 @@ pbio_error_t pbdrv_bluetooth_peripheral_scan_and_connect(pbdrv_bluetooth_periphe
         return PBIO_ERROR_BUSY;
     }
 
-    // Reset peripheral instance but keep user reference.
-    void *user = peri->user;
-    memset(peri, 0, sizeof(pbdrv_bluetooth_peripheral_t));
-    peri->user = user;
+    // Must provide matchers.
+    if (!config || !config->match_adv || !config->match_adv_rsp) {
+        return PBIO_ERROR_INVALID_ARG;
+    }
+
+    // Used to compare subsequent advertisements, so we should reset it.
+    memset(peri->bdaddr, 0, sizeof(peri->bdaddr));
 
     // Initialize operation for handling on the main thread.
     peri->config = config;
     peri->func = pbdrv_bluetooth_peripheral_scan_and_connect_func;
     peri->err = PBIO_ERROR_AGAIN;
+    peri->cancel = false;
     pbio_os_timer_set(&peri->timer, config->timeout);
     pbio_os_request_poll();
 
@@ -221,6 +225,7 @@ pbio_error_t pbdrv_bluetooth_peripheral_disconnect(void) {
 
     // Pass silently for already disconnected.
     if (!pbdrv_bluetooth_is_connected(PBDRV_BLUETOOTH_CONNECTION_PERIPHERAL)) {
+        peri->err = PBIO_SUCCESS;
         return PBIO_SUCCESS;
     }
 
@@ -312,6 +317,7 @@ pbio_error_t pbdrv_bluetooth_await_peripheral_command(pbio_os_state_t *state, vo
 
 void pbdrv_bluetooth_cancel_operation_request(void) {
     // Only some peripheral actions support cancellation.
+    DEBUG_PRINT("Bluetooth operation cancel requested.\n");
     peripheral_singleton.cancel = true;
 }
 
@@ -340,6 +346,7 @@ pbio_error_t pbdrv_bluetooth_start_advertising(bool start) {
     // Already in requested state. This makes it safe to call stop advertising
     // even if it already stopped on becoming connected;
     if (start == is_advertising) {
+        advertising_or_scan_err = PBIO_SUCCESS;
         return PBIO_SUCCESS;
     }
 
@@ -384,6 +391,7 @@ pbio_error_t pbdrv_bluetooth_start_broadcasting(const uint8_t *data, size_t size
 
         if (!is_broadcasting) {
             // Already stopped.
+            advertising_or_scan_err = PBIO_SUCCESS;
             return PBIO_SUCCESS;
         }
         advertising_or_scan_err = PBIO_ERROR_AGAIN;
@@ -395,6 +403,7 @@ pbio_error_t pbdrv_bluetooth_start_broadcasting(const uint8_t *data, size_t size
     // Avoid I/O operations if the user tries to broadcast the same data
     // over and over in a tight loop.
     if (is_broadcasting && pbdrv_bluetooth_broadcast_data_size == size && !memcmp(pbdrv_bluetooth_broadcast_data, data, size)) {
+        advertising_or_scan_err = PBIO_SUCCESS;
         return PBIO_SUCCESS;
     }
     pbdrv_bluetooth_broadcast_data_size = size;
@@ -426,6 +435,7 @@ pbio_error_t pbdrv_bluetooth_start_observing(pbdrv_bluetooth_start_observing_cal
     bool should_observe = callback ? true : false;
 
     if (should_observe == pbdrv_bluetooth_is_observing) {
+        advertising_or_scan_err = PBIO_SUCCESS;
         return PBIO_SUCCESS;
     }
 
@@ -646,6 +656,7 @@ void pbdrv_bluetooth_deinit(void) {
     // is, a task got stuck, so exit forcefully.
     if (advertising_or_scan_err == PBIO_ERROR_AGAIN || peripheral_singleton.err == PBIO_ERROR_AGAIN) {
         // Hard reset without waiting on completion of any process.
+        DEBUG_PRINT("Bluetooth deinit: forcing hard reset due to busy tasks.\n");
         pbdrv_bluetooth_controller_reset_hard();
         return;
     }