I have a project and need your help to specify a gumstix for it.

In this project I will install electric water flow sensors in each apartment of a residential building. At the end of the month the landlord will be able to have the right water use of each apartment.

Those flow sensor emit electric pulses of 5volts in different frequencies depending on the water flow rate.

I need a gumstix witch to receive electric pulses of, lets say, 60 water flow sensors. A software inside the gumstix will process and record those information to generate monthly reports in pdf file format of the water use of each apartment.

A USB pen drive will be used to transport those pdf files to another computer.

Witch gumstix configuration could I use?

Thank You