Fingerprint Cards AB (FPC) uses Byte Paradigm’s SPI Storm serial protocol adapter to test its latest fingerprint area sensor FPC1011F.

Fingerprint sensors allow identifying users through their fingerprints. They are used in many applications such as computers and peripherals, physical access control, crew attendance control, security applications and medical equipment / data storage.

FPC1011F “area” sensor from FPC is an SPI slave device which uses a standard SPI protocol to transmit readout fingerprint image through a standard 4-pin SPI interface.

FPC has developed its own test software based on Byte Paradigm’s free DLL provided with SPI Storm Studio software. This software lets SPI Storm USB device send the right commands to the sensor; it also reads back captured fingerprint image.

Basically, this kind of setup is used during development or for testing small series of sensors, including RMA units. Tests are first conducted by using the built-in test mode of the sensor, which produces a reference pattern that is read-back from PC with SPI Storm adapter. By proceeding this way, the operator must not scan a real fingerprint to get a reference output image. By analyzing the reference pattern, FPC can decide whether more tests are required to investigate potential problems with the sensor.

“Most SPI adapter devices that we have tested were not able to sustain the required data throughput. With the SPI Storm device, we observed the highest effective data throughput we have seen on any USB-connected SPI adapter”, Henrik Storm, Project Manager at Fingerprint Cards AB says.”In particular, the delays between consecutive fingerprint image readout commands are minimal – and the maximum data transfer size supported by SPI Storm is well above our needs”.

SPI Storm is also included in test setup of new developments at Fingerprint Cards AB, especially for the new coming FPC1080A “swipe” sensor. In this case, the fingerprint is read ‘on-the-fly’ while the finger swipes over the sensor. The sensor’s surface is more reduced, which makes the sensor better-fitted for cost-efficient applications.

Image readout speed is critical for such a sensor if one wants to capture a finger being swiped over the sensor at high speed. Multiple overlapping images are generated by the sensor and must be captured. The collection of overlapping images is used for processing the whole fingerprint.

Several hundred images a second might be necessary to transfer from the FPC1080A sensor, depending on the finger swipe speed. This represents a data transfer speed of up to 8 Mbit/s. This minimum throughput must be sustained by the SPI adapter for several seconds. Fingerprint Cards AB has evaluated several SPI adapters on the market. During their tests, SPI Storm was able to reach close to 20 Mbit/s continuously, well above the requirements.

The ability to use different signaling voltages is also appreciated. In the future, the GPO (General-Purpose-Output) port of SPI Storm device could be used as well, as this adds a great deal of flexibility to the testing of such sensors.

About Fingerprint Cards AB

Fingerprint Cards AB (FPC) is a leading provider of fingerprint biometric sensors, processors, algorithms and modules. The company was founded in 1997 and has its head office in Gothenburg, Sweden. Net Sales were 60 MSEK in 2010 (8.7 M$). FPC is listed on Nasdaq OMX Stockholm (FING B). FPC was ranked 8^th in Deloitte Sweden Technology Fast 50 in 2010.