update screenshots

README.md

@@ -172,6 +172,9 @@ PC program source files are located under `./software/pc/`. The compiled program
 
 ### Android
 
-<img src="./imgs/screenshot_connect.png" alt="screenshot_connect" width="300"/>
+<img src="./imgs/screenshot_wifi.png" alt="screenshot_wifi" width="300"/>
+<img src="./imgs/screenshot_bluetooth.png" alt="screenshot_bluetooth" width="300"/>
 
-<img src="./imgs/screenshot_control.png" alt="screenshot_control" width="600"/>
+<img src="./imgs/screenshot_control1.png" alt="screenshot_control1" width="600"/>
+
+<img src="./imgs/screenshot_control2.png" alt="screenshot_control2" width="600"/>