Espressif Systems ESP32 Instruction Set page 95

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�� Notes:
• After ESP32 Server enables BLE SPP, the data received from serial port will be transmitted to the BLE
client directly.
• If the ESP32 Client does not enable BLE SPP first, or uses other device as BLE client, then the BLE
client needs to listen to the notification or indication first. For example, if the ESP32 Client does not
enable BLE SPP first, then it should enable listening with command AT+BLEGATTCWR=0,3,7,1,1 first
for the ESP32 Server to transmit successfully.
For the same service, the <srv_index> on the ESP32 Client side equals the <srv_index> on the ESP32
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Server side plus 2.
9.5.2.3. Usage Scenarios
1. Bluetooth networking
BLE can be used to transfer the Wi-Fi SSID and Password in a Bluetooth network.
• Use AT+BLEGATTCWR for the client to pass on the SSID and password to the server.
Use AT+BLEGATTSNTFY for the server to pass on the SSID and password to the client.
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Details can be found in Section 9.5.2.1.
2. Transparent data transmission
The ESP32 AT does not support transparent data transmission over BLE for the time being.
However, users can use that basic data-transmission method to simulate the transparent
data transmission process where Host MCU can filter the data information.
• Call AT+BLEGATTCWR continuously for the client to transfer data to the server.
Call AT+BLEGATTSNTFY continuously for the server to transfer data to the client.
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Details can be found in Section 9.5.2.1.
3. OTA firmware upgrade
OTA firmware upgrade can also be implemented over BLE.
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9. AT Commands Examples
2019.06