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+++ b/README.md
@@ -33,4 +33,17 @@ git clone https://github.com/colour93/esp32-car.git
 
 ## BLE 串口通信协议
 
+其他设备与 ESP32 通信采用 BLE 的 GATT 协议，其服务默认为 Nordic 串口服务，可以在 `src/consts.h` 中修改。
+
+```cpp
+# 服务与特征 UUID
+#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"
+#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
+#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
+```
+
+数据分为主动发送和被动接收两种，主动发送的特征值为 `CHARACTERISTIC_UUID_TX`，被动接收的特征值为 `CHARACTERISTIC_UUID_RX`。
+
+同时一些状态信息会主动发送。
+
 [数据包格式](./packet.md)
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