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RFID using ADI Blackfin Processor


RFID Reader Using ADI’s Blackfin Processor

RFID technology enables many applications by allowing concurrent monitoring of multiple items; such as inventory control, logistics management, and toll collection. The technology is transforming the existing applications and enabling the new ones. Front end of the system start with small tags attached on the units of interest; the tags convey information in the form of a bit stream to an RFID reader. At the back end, a server-based system maintains and updates the tag database.

Most of the conventional RFID readers employ more than one processor; a signal processor interface to an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC), and a network processor communicates with a server for information storage and retrieval. This article describes how these application managed by a single Blackfin processor.

RFID System Overview

Figure1. Simplified representation of an RFID system.

Blackfin processors provide connectivity to both wired and wireless networks. For example, ADSP-BF536 and ADSP-BF537 have a 10-Base-T/100-Base-T Ethernet MAC on chip which facilitates the wired network. On the wireless network, all Blackfin processors can connect directly to both 802.15.4 ZigBee and IEEE 802.11 chipsets via the SPI and SPORT peripherals.

Figure2. Example of the wired and wireless Blackfin RFID system.

In addition, Blackfin processors include a parallel peripheral interface (PPI), which can connect directly to ADCs and DACs. For RFID application, the PPI is first configured in transmit mode, and the processor sends a digital sequence to a DAC. The transmitted sequence is converted to an analog signal, which is then upconverted and send out to excite the local RFID tags. Simultaneously, the PPI is reconfigured as a receiver; so that the downconverted RF signal can be sampled by ADC and bought into the Blackfin directly. ADI’s MxFE IC constitutes the highest performance narrow-band receivers; the device includes ADC, DAC, low noise amplifier, mixers, AGC circuitry, and programmable filters. It forms the great interface between the tags and reader.

Figure3. Block diagram of a representative MxFE IC, the AD9861

Software components for the Blackfin RFID infrastructure are available on the website. All drivers necessary to interface to the mixed-signal, front-end IC, as well as a DMA driver that is very useful in moving data through a system are available. The uClinux-based network stack and SQL database engines are also available. Other than that, additional features such as 802.11 Wi-Fi cards, USB thumb drives, and CompactFlash card interfaces, can very quickly be integrated with Blackfin devices.

In conclusion, a convergent processor such as Blackfin processor managed to provide both signal processing and control function for RFID system. It enables a lower cost and faster time to market solution for the upcoming RFID application.