Android Application: Employee Time Clock

I need a lightweight time clock application to run on a phone or tablet that will allow employees to punch-in/out on a daily basis, then email the log when specified. For my specific needs, users (up to 5) need to have a unique pin to log their time with a simple start & stop button. When a user ends/stops time, it needs to allow them to enter tips (if enabled). The password protected back-end needs to include the ability to change site name, enable tip logging, specify log recipient and dates to send logs. The final emailed log should include all the in/out times with total hours and tips shown on each line and a summary at the bottom saying how much for each employee for the period.