Software can be downloaded from GitHub: https://github.com/projects22/OBD2-RPM-Meter
A rev counter connected to OBD2 Bluetooth diagnostic plug with ELM327. This RPM meter works with all OBD protocols. The Android program is written using MIT App Inventor. The Android device, phone or tablet, have to be paired with the BT plug. The display is digital and traditional analogue. The app request data from the car ECU every 0.5 sec. The app APK file, has to be transferred to the device and when opened it instructs how to be installed..aia file is the app and can be modified in the MIT App Inventor.