Suprema Employs Blackfin® for Fingerprint Recognition
Increasingly, vital aspects of our lives are accessed and managed via some form of security mechanism - a PIN, a key, a signature, a password, or that old standard: "mom's maiden name." Many kinds of systems require secure identification. Let's start with ATM machines and move on to networked servers and storage, and the portable devices like laptops, mobile PCs, cell phones, and PDAs that are needed to access them. Then there are time-and-attendance devices, point-of-sale (POS) devices, door locks, buildings and cars, not to mention government-related security issues, which require indisputable user identification.
Biometrics, security systems that identify individuals by means of a physical or behavioral characteristic, are more dependable and less cumbersome than traditional methods. Fingerprints, which are unique to an individual, are a very reliable form of biometric identification. A small reader attached to a PC or wireless device can capture a fingerprint, reduce it to a mathematical formula, and match it with one on file on a server.
Suprema, a leading biometrics company, offers fingerprint algorithms for PC-based and embedded applications with low-cost OEM modules that can be deployed in a wide variety of biometrics applications. The algorithms, which won first place in a worldwide fingerprint verification competition, run on Blackfin processors from Analog Devices, Inc. (ADI).
Price/performance and low power consumption played a big role in Suprema's decision to use Blackfin processors. These attributes help Suprema's customers directly address the growing need for low-cost, battery-operated biometrics systems. "There were many high-performance processors in addition to Blackfin on the market, but they were power hungry and expensive," said Young S. Moon, Director, Suprema, Inc. "For us, it was crucial to reduce overall costs and power consumption while maximizing performance. Choosing Blackfin processors was smart. It allowed us to reach contradictory goals at once."
Types of Sensors
Optical sensors operate by placing a finger on a plate that is illuminated by LED light sources. Through a prism and a system of lenses, the image is projected on a CMOS image sensor. Using frame grabber techniques, the image is stored and ready for analysis.
Thermal sensors contain an array of temperature measurement pixels that make a distinction between the temperature of the skin in the ridges and the temperature of the air in the valleys. One dimension of this sensor can be fairly small since a temperature scan can be obtained by sweeping the finger over the sensor.
Capacitive sensors use the difference between the skin-sensor and air-sensor contact in terms of the capacitive values. When a finger is placed on the sensor, an array of pixels measures the variation in capacity between the valleys and the ridges in the fingerprint. This method is possible since there is a difference between skin-sensor and air-sensor contact in terms of capacitive values.
Electric Field sensors create an electric field from a ring around the sensing area, with which an array of pixels measure variations caused by the ridges and valleys in the fingerprint. The variations are detected in the conductive layer of the skin, beneath the skin surface or epidermis.
Rich Set of Peripherals
Suprema's products include the UniFinger™ SFM3000 and SFM3500 modules. The modules are embedded solutions that comprise a standalone processing board and a Blackfin processor that runs the company's fingerprint-recognition algorithm. Suprema also offers OEMs a choice of fingerprint sensors (optical, thermal, capacitive, and electric field) from leading vendors.
With Blackfin on board, the UniFinger can store thousands of fingerprints in internal memory and can provide a full range of biometric functions, including enrollment, one-to-one verification and one-to-many identification.
That's because Blackfin processors embody a new breed of 16/32-bit embedded processors designed specifically to meet the computational demands and power constraints of today's embedded applications. Blackfin delivers breakthrough signal-processing performance and power efficiency while also offering a full 32-bit RISC MCU programming model on a single-instruction, multiple-data (SIMD) architecture.
Another important reason Suprema chose the Blackfin ADSP-BF531 processor was because it contains a rich set of peripherals that are connected to the core via several high-bandwidth busses. The peripherals provide flexibility in system configuration as well as overall system performance. By combining industry-standard interfaces with a high-performance signal-processing core, users can develop cost-effective solutions quickly without the need for expensive external components.
The system peripherals include a universal asynchronous receiver/transmitter (UART) port, a serial peripheral interface (SPI), two serial ports (SPORTs), four general-purpose timers (three with pulse width modulation (PWM) capability), a real-time clock, a watchdog timer, and a high-speed parallel peripheral interface (PPI).
All of the peripherals, except for the general-purpose I/O, real-time clock, and timers, are supported by the direct memory access (DMA) architecture. There is also a separate memory DMA channel dedicated to data transfers between the processor's various memory spaces, including external SDRAM and asynchronous memory. "Having a full complement of peripherals and interfaces, such as the UART, SPI, timers, and an SDRAM controller, enabled a 'glueless' system design," said Moon. "This helped reduce our overall costs significantly."
Low Power Consumption
Suprema's modules are likely to be deployed in battery-operated biometrics devices in a wide variety of markets, so low power consumption was mandatory. The company made the right choice with Blackfin, as the processor provides world-class power management and performance. Designed in a low-power and low-voltage design methodology, Blackfin features dynamic power management and the ability to vary both the voltage and frequency of operation to significantly lower overall power consumption. Varying the voltage and frequency can result in a substantial reduction in power consumption, compared with just varying the frequency of operation. This translates into longer battery life for portable appliances. The ADSP-BF531 processor also includes an on-chip voltage regulator in support of the processor's dynamic power management capability, providing a range of core voltage levels from a single 2.25V to 3.6V inputs.
To speed the development process, Suprema used ADI's VisualDSP++, an easy-to-install and easy-to-use integrated software development and debugging environment (IDDE) that enables efficient management of projects from start to finish from within a single interface. Suprema also used ADI's high-performance PCI-based emulator (HPPCI) that works in conjunction with the JTAG interface (the test access port used to monitor and control the target board during emulation).
Suprema used ADI's VisualDSP++ Kernel (VDK) library for features such as task scheduling and inter-processor communication. The VDK provides state-of-the-art scheduling and resource allocation techniques tailored specifically to address the memory and timing constraints of programming. These techniques enable engineers to use example code more efficiently, often eliminating the need to start projects from scratch and saving development and debugging time. To save users even more time, VDK also has standard libraries and frameworks with defined APIs that allow easy inclusion of boilerplate, class libraries, and value-added intellectual property (IP) code.
With Blackfin's excellent performance that helped win an award, and more peripherals than a designer could wish for, it's clear that Blackfin met its price/performance goals at Suprema. "We wanted much better performance at a lower price," said Moon, "and we got it." Suprema plans to apply different versions of Blackfin to its future product lines.
For more information about Suprema, visit the company's Web site at www.supremainc.com.
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