/products/arduino/arduino-tutorials/b/blog/posts/how-to-use-android-app-to-control-linknode-r4LinkNode R4 is an open source 4-Channel relay controller which is powered by the ESP8266 WiFi SoC. The following will introduce how to use Android APP to control the LinkNode R4.Steps1. Install Android APPDownload the APK file from the github and insten-USTelligent Community 12