Here you will find the library written for the Attendance System. This library interfaces with the R30x series of the fingerprint scanners, there is no significant difference among the different devices in the series, and I have used R307 for this particular system.
This code is the actual implementation of the library used in the Attendance System (link above). You will find the code for comminicating with the fingerprint device, mobile device, display device and I/O operations on the EEPROM.
You can find the mobile application here
Note: If you have a question, you can open an issue and tag it with question or help wanted labels. But do make sure that you have actually read the code and have made some degree of understanding before opening a thread.