HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Control Technology, Microelectronics and Nanotechnologythe hardware that are occasionally idle. One potential application issmart cellular phones that support multiple communication and dataprotocols, one at a time. As the phone passes from a geographic regionthat is served by one protocol into a region that is served byanother, the hardware is automatically reconfigured. This is thereconfigurable computing approach.Reconfigurable computing makes it feasible to achieve greaterfunctionality with simpler hardware. The cost of additional features isreduced to the cost of the memory required to store the logic needed.Reconfigurable computing has the ability to execute larger hardwaredesigns with fewer gates with the flexibility of a software-basedsolution and the execution speed of a more traditional, hardwarebasedapproach. Reconfigurable computing allows the addition ofnew features in the field and rapid implementation of new standardsand protocols on an as-needed basis.In the multiprotocol cellular phone, it is possible to support asmany protocols as can fit into the available on-board memory. Newprotocols could even be uploaded from a base station to the handheldphone on an as-needed basis, requiring no additional memory.Since systems based on reconfigurable computing areupgradable in the field, such changes extend the useful life of thesystem. Reconfigurable computing eliminates a large amount of developmenteffort. The logic design remains flexible and allows an incrementaldesign flow.Reconfigurable HardwareTraditional FPGAs are configurable, but they are not run-timereconfigurable. Older FPGAs read their configuration from a serialEEPROM, one bit at a time. This means that the FPGA must be reprogrammedin its entirety. This is compatible with configurable computingapplications, but it is not adequate for reconfigurable computing.In order to have run-time reconfiguration, the FPGAs need tohave on-the-fly reprogrammability. Partial reprogrammability is theability to leave most of the internal logic in place and change just onepart. Atmel 40K and Xilinx 62xx series FPGAs have this feature. Anygate or set of gates may be changed without affecting the state of theothers. An externally visible internal state means that it is possible to©2001 by The Fairmont Press, Inc. All rights reserved.