In this review we will take a closer look at a small fingerprint scanner module with a serial interface that can be easily interfaced to a microcontroller, an Arduino, a Raspberry Pi, a computer, in short, to anything that can communicate over a standard asynchronous serial link. Adding such a module to a project would give it secure access capabilities and can help you to prevent for instance pirates, children or cats from (mis)using your device.

GT-521F52 fingerprint scanner module

The fingerprint scanner under scrutiny here is a GT-521F52 high performance module from ADH Technology (there also exists a GT-521F32 which has less memory). Similar to the older GT-511 module, it is a one-chip optical sensor module with embedded recognition and storage functions, and only two wires are required to communicate with it. The specifications also mention a USB communication protocol, but how and where unfortunately isn't clear.

 
Info & statistics from the GT-521F52.

The GT-521F52 stores Up to 3,000 fingerprints

The tiny module measuring just 36.1 by 21 mm does all the hard work for you, all that remains to do is send it some commands and interpret the data it returned. Fingerprints are captured by and stored on the module itself. The scratch-proof optical sensor has a resolution of 450 dpi and produces 258 by 202 pixel images. The scans are converted by the module into so-called ‘templates’. The GT-521F52 has room for storing a whopping 3,000 templates, the “32” can store only 200… Templates can be read from the module, one by one or the complete database in one fell swoop, but they can also be written to it, making sharing of templates between different modules easy.