BLE notification stack overflow

[BARS2022]

Hi!
I want to start BLE server with the notifications on ESP32. I was run a "gatts_demo" example in Visual Studio 2022. I make notification sends with RTOS function:

Code: [Select all] [Expand/Collapse]

1. void V_notif_task(void *p)
2. {
3.  
4.     uint8_t notify_data[32];
5.    
6.     memcpy(notify_data, "notify sended", 13);
7.    
8.     while (1)
9.     {
10.         if (ne == true)
11.         {
12.             if (gatts_if_for_indicate == ESP_GATT_IF_NONE)
13.             {
14.                 printf("cannot indicate because gatts_if_for_indicate is NONE\n");
15.             }
16.             else
17.             {
18.                 uint16_t attr_handle = 0x002a;
19.  
20.                 //the size of notify_data[] need less than MTU size
21.                 esp_ble_gatts_send_indicate(gatts_if_for_indicate, 0, attr_handle, 13, notify_data, false);
22.             }
23.         }
24.  
25.         vTaskDelay(1000);
26.     }
27. }
28.  
29.     case ESP_GATTS_WRITE_EVT: {
30.         ESP_LOGI(GATTS_TAG, "GATT_WRITE_EVT, conn_id %d, trans_id %d, handle %d", param->write.conn_id, param->write.trans_id,
31.  param->write.handle);
32.         if (!param->write.is_prep){
33.             ESP_LOGI(GATTS_TAG, "GATT_WRITE_EVT, value len %d, value :", param->write.len);
34.             esp_log_buffer_hex(GATTS_TAG, param->write.value, param->write.len);
35.             if (gl_profile_tab[PROFILE_A_APP_ID].descr_handle == param->write.handle && param->write.len == 2){
36.                 uint16_t descr_value = param->write.value[1]<<8 | param->write.value[0];
37.                 if (descr_value == 0x0001){
38.                     if (a_property & ESP_GATT_CHAR_PROP_BIT_NOTIFY){
39.                         ESP_LOGI(GATTS_TAG, "notify enable");
40.                         uint8_t notify_data[15];
41.                         for (int i = 0; i < sizeof(notify_data); ++i)
42.                         {
43.                             notify_data[i] = i%0xff;
44.                         }
45.                         //the size of notify_data[] need less than MTU size
46.                         esp_ble_gatts_send_indicate(gatts_if, param->write.conn_id, gl_profile_tab[PROFILE_A_APP_ID].char_handle, sizeof(notify_data), notify_data, false);
47.  
48.             ne = true;
49.         }
50.         }
51.  
52. xTaskCreate(v_test_task, "test_task", configMINIMAL_STACK_SIZE, NULL, 8, NULL);

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I receive a notifications on BLE client, but after several notifications ESP32 crush with error:

Code: Select all

 ***ERROR*** A stack overflow in task test_task has been detected.

Why is this happening? Function esp_ble_gatts_send_indicate don't clear memory after work ending? How to clear the memory?

[chegewara]

This is one of most common issues.
When you are using printf like functions in task then minimal stack is not enough.

[BARS2022]

The function printf() is not called during normal operation of the software. I deleted the printf(), but the ESP32 is also crashing.

[ESP_Sprite]

'printf-like functions' also include logging functions like ESP_LOGI and esp_log_buffer_hex. An easier fix may be to give more stack space to the task: take out configMINIMAL_STACK_SIZE and change it to something like 4096 or 8192.