BLE: limited number of services and characteristics

[Paolo_g]

Hi,
I'm using BLE on ESP32.
The ESP32 board is my server.
I have a problem: the number of services is limited to 7, and also the number of characteristics is limited to 7.
If I try to use more services or characteristics the client (the smartphone or another ESP32 board) can't see them.
Is it possible to use more services and characteristics?
I have tried to see if there are some #define in the .h files that limit this number, but I don't have found anything.
Thank you

[chegewara]

There is parameter handles number
https://github.com/nkolban/ESP32_BLE_Ar ... Server.cpp

[Paolo_g]

Thank you very much!
If other people are interested in this: the parameter numHandles of the function createService allows you to specify the number of characteristics.
Just out of curiosity: is it possible to change also the number of services?

[chegewara]

There is no services number limit. Only limit is handles number which is 0xFFFF.

[Eckii24]

I have the same issue with the number of services for the esp32.
The following code stops after starting the seventh service.

Is the number of possible BLE-services on an ESP32 limited or can I change something in the code to expand the number?

Code: [Select all] [Expand/Collapse]

1. /*
2.     Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleServer.cpp
3.     Ported to Arduino ESP32 by Evandro Copercini
4.     updates by chegewara
5. */
6.  
7. #include <BLEDevice.h>
8. #include <BLEUtils.h>
9. #include <BLEServer.h>
10.  
11. // See the following for generating UUIDs:
12. // https://www.uuidgenerator.net/
13.  
14. #define SERVICE1_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
15. #define SERVICE2_UUID        "5fafc201-1fb5-459e-8fcc-c5c9c331914b"
16. #define SERVICE3_UUID        "6fafc201-1fb5-459e-8fcc-c5c9c331914b"
17. #define SERVICE4_UUID        "7fafc201-1fb5-459e-8fcc-c5c9c331914b"
18. #define SERVICE5_UUID        "8fafc201-1fb5-459e-8fcc-c5c9c331914b"
19. #define SERVICE6_UUID        "9fafc201-1fb5-459e-8fcc-c5c9c331914b"
20. #define SERVICE7_UUID        "4fafc301-1fb5-459e-8fcc-c5c9c331914b"
21. #define SERVICE8_UUID        "4fafc401-1fb5-459e-8fcc-c5c9c331914b"
22. #define SERVICE9_UUID        "4fafc501-1fb5-459e-8fcc-c5c9c331914b"
23. #define SERVICE10_UUID       "4fafc601-1fb5-459e-8fcc-c5c9c331914b"
24.  
25. void setup() {
26.   Serial.begin(115200);
27.   Serial.println("Starting BLE work!");
28.  
29.   BLEDevice::init("Long name works now");
30.   BLEServer *pServer = BLEDevice::createServer();
31.  
32.   Serial.println("Service1");
33.   BLEService *pService1 = pServer->createService(SERVICE1_UUID);
34.   BLECharacteristic *pCharacteristic1 = pService1->createCharacteristic(SERVICE1_UUID, BLECharacteristic::PROPERTY_READ);
35.   pCharacteristic1->setValue("Hello World says Neil");
36.   pService1->start();
37.  
38.   Serial.println("Service2");
39.   BLEService *pService2 = pServer->createService(SERVICE2_UUID);
40.   BLECharacteristic *pCharacteristic2 = pService2->createCharacteristic(SERVICE2_UUID, BLECharacteristic::PROPERTY_READ);
41.   pCharacteristic2->setValue("Hello World says Neil");
42.   pService2->start();
43.  
44.   Serial.println("Service3");
45.   BLEService *pService3 = pServer->createService(SERVICE3_UUID);
46.   BLECharacteristic *pCharacteristic3 = pService3->createCharacteristic(SERVICE3_UUID, BLECharacteristic::PROPERTY_READ);
47.   pCharacteristic3->setValue("Hello World says Neil");
48.   pService3->start();
49.  
50.   Serial.println("Service4");
51.   BLEService *pService4 = pServer->createService(SERVICE4_UUID);
52.   BLECharacteristic *pCharacteristic4 = pService4->createCharacteristic(SERVICE4_UUID, BLECharacteristic::PROPERTY_READ);
53.   pCharacteristic4->setValue("Hello World says Neil");
54.   pService4->start();
55.  
56.   Serial.println("Service5");
57.   BLEService *pService5 = pServer->createService(SERVICE5_UUID);
58.   BLECharacteristic *pCharacteristic5 = pService5->createCharacteristic(SERVICE5_UUID, BLECharacteristic::PROPERTY_READ);
59.   pCharacteristic5->setValue("Hello World says Neil");
60.   pService5->start();
61.  
62.   Serial.println("Service6");
63.   BLEService *pService6 = pServer->createService(SERVICE6_UUID);
64.   BLECharacteristic *pCharacteristic6 = pService6->createCharacteristic(SERVICE6_UUID, BLECharacteristic::PROPERTY_READ);
65.   pCharacteristic6->setValue("Hello World says Neil");
66.   pService6->start();
67.  
68.   Serial.println("Service7");
69.   BLEService *pService7 = pServer->createService(SERVICE7_UUID);
70.   BLECharacteristic *pCharacteristic7 = pService7->createCharacteristic(SERVICE7_UUID, BLECharacteristic::PROPERTY_READ);
71.   pCharacteristic7->setValue("Hello World says Neil");
72.   pService7->start();
73.  
74.   Serial.println("Service8");
75.   BLEService *pService8 = pServer->createService(SERVICE8_UUID);
76.   BLECharacteristic *pCharacteristic8 = pService8->createCharacteristic(SERVICE8_UUID, BLECharacteristic::PROPERTY_READ);
77.   pCharacteristic8->setValue("Hello World says Neil");
78.   pService8->start();
79.  
80.   Serial.println("Service9");
81.   BLEService *pService9 = pServer->createService(SERVICE9_UUID);
82.   BLECharacteristic *pCharacteristic9 = pService9->createCharacteristic(SERVICE9_UUID, BLECharacteristic::PROPERTY_READ);
83.   pCharacteristic9->setValue("Hello World says Neil");
84.   pService9->start();
85.  
86.   Serial.println("Service10");
87.   BLEService *pService10 = pServer->createService(SERVICE10_UUID);
88.   BLECharacteristic *pCharacteristic10 = pService10->createCharacteristic(SERVICE10_UUID, BLECharacteristic::PROPERTY_READ);
89.   pCharacteristic10->setValue("Hello World says Neil");
90.   pService10->start();
91.  
92.  
93.   BLEDevice::startAdvertising();
94.   Serial.println("Characteristic defined! Now you can read it in your phone!");
95. }
96.  
97. void loop() {
98.   // put your main code here, to run repeatedly:
99.   delay(2000);
100. }

GeSHi © Codebox Plus Extension

[chegewara]

I tried this code with esp-idf in PIO and i found this, which is very strange:

Code: Select all

BT_GATT: GATTS_ReserveHandles: no free handle blocks

You can try to use this function and decrease numHandles:
https://github.com/nkolban/esp32-snippe ... rver.h#L67

Each characteristic needs 2 handles and descriptor 1 handle.

[dhiraj_gehlot]

Hello,

I am facing exactly same issue.
I am using Arduino IDE to code ESP-32 module. Currently I am using BLE functionality to communicate with our mobile app.
There seems to be limitation on number of BLE services which can be created. Even If I create more than 7 services, only 6 are visible.

I find some link which states solution in ESP-IDF but I couldn't find this variable GATT_MAX_SR_PROFILES or bt_target.h file:
https://github.com/espressif/esp-idf/issues/1644
https://github.com/espressif/esp-idf/issues/5495

Can someone help me?