esp-idf/examples/bluetooth/bluedroid/ble/gatt_client/README.md
2023-01-13 15:05:34 +08:00

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| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C6 | ESP32-H4 | ESP32-S3 |
| ----------------- | ----- | -------- | -------- | -------- | -------- | -------- |
# ESP-IDF Gatt Client Example
This example shows how to use ESP APIs to create a GATT Client.
## How to Use Example
Before project configuration and build, be sure to set the correct chip target using:
```bash
idf.py set-target <chip_name>
```
To test this example, you first run the [gatt_server_demo](../gatt_server), which creates services and starts advertising. `Gatt_client_demo` will start scanning and connect to the `gatt_server_demo` automatically.
This example will enable gatt server's notification function once the connection is established and then the devices start exchanging data.
Please, check this [tutorial](tutorial/Gatt_Client_Example_Walkthrough.md) for more information about this example.
### Hardware Required
* A development board with ESP32/ESP32-C3/ESP32-H4/ESP32-C2/ESP32-S3 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
* A USB cable for Power supply and programming
See [Development Boards](https://www.espressif.com/en/products/devkits) for more information about it.
### Build and Flash
Run `idf.py -p PORT flash monitor` to build, flash and monitor the project.
(To exit the serial monitor, type ``Ctrl-]``.)
See the [Getting Started Guide](https://idf.espressif.com/) for full steps to configure and use ESP-IDF to build projects.
### Settings for UUID128
This example works with UUID16 as default. To change to UUID128, follow this steps:
1. Change the UIID16 to UUID128. You can change the UUID according to your needs.
```c
// Create a new UUID128 (using random values for this example)
static uint8_t gatts_xxx_uuid128[ESP_UUID_LEN_128] = {0x06, 0x18, 0x7a, 0xec, 0xbe, 0x11, 0x11, 0xea, 0x00, 0x16, 0x02, 0x42, 0x01, 0x13, 0x00, 0x04};
```
By adding this new UUID128, you can remove the `#define` macros with the old UUID16.
2. Change the structure to:
```c
static esp_bt_uuid_t xxx_uuid = {
.len = ESP_UUID_LEN_128,
.uuid = {.uuid128 = { 0 },},
};
```
3. Add the new UUID128 to the profile.
```c
// Copy the new UUID128 to the profile
memcpy(xxx_uuid.uuid.uuid128, gatts_xxx_uuid128, ESP_UUID_LEN_128);
```
4. Edit the `ESP_GATTC_SEARCH_RES_EVT` in order to filter the new UUID128.
```c
case ESP_GATTC_SEARCH_RES_EVT: {
ESP_LOGI(GATTC_TAG, "SEARCH RES: conn_id = %x is primary service %d", p_data->search_res.conn_id, p_data->search_res.is_primary);
ESP_LOGI(GATTC_TAG, "start handle %d end handle %d current handle value %d", p_data->search_res.start_handle, p_data->search_res.end_handle, p_data->search_res.srvc_id.inst_id);
if (p_data->search_res.srvc_id.uuid.len == ESP_UUID_LEN_128) {
if(memcmp(p_data->search_res.srvc_id.uuid.uuid.uuid128, gatts_xxx_uuid128, ESP_UUID_LEN_128) == 0){
ESP_LOGI(GATTC_TAG, "service uuid128 found");
get_server = true;
gl_profile_tab[PROFILE_X_APP_ID].service_start_handle = p_data->search_res.start_handle;
gl_profile_tab[PROFILE_X_APP_ID].service_end_handle = p_data->search_res.end_handle;
} else {
ESP_LOGE(GATTC_TAG, "service not found");
}
}
break;
```
## Example Output
```
I (0) cpu_start: Starting scheduler on APP CPU.
I (525) BTDM_INIT: BT controller compile version [1342a48]
I (525) system_api: Base MAC address is not set
I (525) system_api: read default base MAC address from EFUSE
I (535) phy_init: phy_version 4670,719f9f6,Feb 18 2021,17:07:07
I (945) GATTC_DEMO: REG_EVT
I (955) GATTC_DEMO: scan start success
I (1115) GATTC_DEMO: 08 ef 3b a7 04 41
I (1115) GATTC_DEMO: searched Adv Data Len 9, Scan Response Len 15
I (1115) GATTC_DEMO: searched Device Name Len 13
I (1125) GATTC_DEMO: LG CM2760(41)
I (1125) GATTC_DEMO:
I (1425) GATTC_DEMO: 08 ef 3b a7 04 41
I (1425) GATTC_DEMO: searched Adv Data Len 9, Scan Response Len 15
I (1425) GATTC_DEMO: searched Device Name Len 13
I (1435) GATTC_DEMO: LG CM2760(41)
I (1435) GATTC_DEMO:
I (1865) GATTC_DEMO: 38 68 a4 69 bb 7c
I (1865) GATTC_DEMO: searched Adv Data Len 31, Scan Response Len 14
I (1865) GATTC_DEMO: searched Device Name Len 0
I (1875) GATTC_DEMO:
I (2185) GATTC_DEMO: 38 68 a4 69 bb 7c
I (2185) GATTC_DEMO: searched Adv Data Len 31, Scan Response Len 14
I (2185) GATTC_DEMO: searched Device Name Len 0
I (2185) GATTC_DEMO:
```
## Troubleshooting
For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.