examples: le_counter, le_streamer - use att_server_request_can_send_now_event

example/le_counter.c

@@ -100,6 +100,7 @@ static void le_counter_setup(void){
 
     // setup ATT server
     att_server_init(profile_data, att_read_callback, att_write_callback);    
+    att_server_register_packet_handler(packet_handler);
 
     // setup advertisements
     uint16_t adv_int_min = 0x0030;
@@ -118,37 +119,11 @@ static void le_counter_setup(void){
 }
 /* LISTING_END */
 
-/* 
- * @section Packet Handler
- *
- * @text The packet handler is only used to stop the counter after a disconnect
- */
-
-/* LISTING_START(packetHandler): Packet Handler */
-static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
-	switch (packet_type) {
-		case HCI_EVENT_PACKET:
-			switch (hci_event_packet_get_type(packet)) {
-                case BTSTACK_EVENT_STATE:
-                    if (btstack_event_state_get_state(packet) == HCI_STATE_WORKING){
-                        printf("LE Counter Demo ready.\n");
-                        beat();
-                    }
-                    break;
-                case HCI_EVENT_DISCONNECTION_COMPLETE:
-                    le_notification_enabled = 0;
-                    break;
-			}
-            break;
-	}
-}
-/* LISTING_END */
-
 /*
  * @section Heartbeat Handler
  *
  * @text The heartbeat handler updates the value of the single Characteristic provided in this example,
- * and sends a notification for this characteristic if enabled, see Listing heartbeat.
+ * and request a ATT_EVENT_CAN_SEND_NOW to send a notification if enabled see Listing heartbeat.
  */
 
  /* LISTING_START(heartbeat): Hearbeat Handler */
@@ -165,13 +140,43 @@ static void beat(void){
 static void heartbeat_handler(struct btstack_timer_source *ts){
     if (le_notification_enabled) {
         beat();
-        att_server_notify(ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE, (uint8_t*) counter_string, counter_string_len);
+        att_server_request_can_send_now_event();
     }
     btstack_run_loop_set_timer(ts, HEARTBEAT_PERIOD_MS);
     btstack_run_loop_add_timer(ts);
 } 
 /* LISTING_END */
 
+/* 
+ * @section Packet Handler
+ *
+ * @text The packet handler is used to:
+ *        - stop the counter after a disconnect
+ *        - send a notification when the requested ATT_EVENT_CAN_SEND_NOW is received
+ */
+
+/* LISTING_START(packetHandler): Packet Handler */
+static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
+    switch (packet_type) {
+        case HCI_EVENT_PACKET:
+            switch (hci_event_packet_get_type(packet)) {
+                case BTSTACK_EVENT_STATE:
+                    if (btstack_event_state_get_state(packet) == HCI_STATE_WORKING){
+                        printf("LE Counter Demo ready.\n");
+                        beat();
+                    }
+                    break;
+                case HCI_EVENT_DISCONNECTION_COMPLETE:
+                    le_notification_enabled = 0;
+                    break;
+                case ATT_EVENT_CAN_SEND_NOW:
+                    att_server_notify(ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE, (uint8_t*) counter_string, counter_string_len);
+                    break;
+            }
+            break;
+    }
+}
+/* LISTING_END */
 
 /*
  * @section ATT Read

example/le_streamer.c

@@ -183,10 +183,11 @@ static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *pack
                     printf("ATT MTU = %u\n", mtu);
                     test_data_len = mtu - 3;
                     break;
+                case ATT_EVENT_CAN_SEND_NOW:
+                    streamer();
+                    break;
             }
     }
-    // try sending whenever something happens
-    streamer();
 }
 
 /* LISTING_END */
@@ -201,21 +202,20 @@ static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *pack
 static void streamer(void){
     // check if we can send
     if (!le_notification_enabled) return;
-    if (!att_server_can_send_packet_now()) return;
 
     // create test data
-    int i;
     counter++;
     if (counter > 'Z') counter = 'A';
-    for (i=0;i<sizeof(test_data);i++){
+    memset(test_data, counter, sizeof(test_data));
-        test_data[i] = counter;
-    }
 
     // send
     att_server_notify(ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE, (uint8_t*) test_data, test_data_len);
 
     // track
     test_track_sent(test_data_len);
+
+    // request next send event
+    att_server_request_can_send_now_event();
 } 
 /* LISTING_END */
 
@@ -223,8 +223,8 @@ static void streamer(void){
  * @section ATT Write
  *
  * @text The only valid ATT write in this example is to the Client Characteristic Configuration, which configures notification
- * and indication. If the ATT handle matches the client configuration handle, the new configuration value is stored and used
+ * and indication. If the ATT handle matches the client configuration handle, the new configuration value is stored.
- * in the heartbeat handler to decide if a new value should be sent. See Listing attWrite.
+ * If notifications get enabled, an ATT_EVENT_CAN_SEND_NOW is requested. See Listing attWrite.
  */
 
 /* LISTING_START(attWrite): ATT Write */
@@ -235,6 +235,9 @@ static int att_write_callback(hci_con_handle_t con_handle, uint16_t att_handle,
         case ATT_CHARACTERISTIC_0000FF11_0000_1000_8000_00805F9B34FB_01_CLIENT_CONFIGURATION_HANDLE:
             le_notification_enabled = little_endian_read_16(buffer, 0) == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION;
             printf("Notifications enabled %u\n", le_notification_enabled);            
+            if (le_notification_enabled){
+                att_server_request_can_send_now_event();
+            }
             test_reset();
             break;
         case ATT_CHARACTERISTIC_0000FF12_0000_1000_8000_00805F9B34FB_01_VALUE_HANDLE: