Kontinuerlig RFID-detektering för batteridrivna system
This report deals with RFID systems and how to detect nearby tags with the Mifare standard using only a microcontroller and an antenna circuit.The aim was to investigate whether there was any possibility to continuously search for a nearby tag for a system operated with batteries without compromising the lifespan of the battery. At this time the system would take too long time to wake up and look for a tag to give a satisfactory battery lifespan, which should be done a couple of times every second.The report has two issues, namely:Is it possible to direct the microprocessor to detect and identify a nearby tag after the Mifare standard?What hardware is required for this to be possible?As the research method to provide answers to the above questions an action research was used. This approach has meant that the group worked on information retrieval, examined existing solutions, tested their own solutions and documented the results.The group examined an existing solution that can search for nearby tags with minimal energy consumption. An antenna circuit was built that was connected to the processor. The program code was made in AVR Studio on a PC and programmed with a AVR one!. The processor was in an AVR Xplain development board for processors made by Atmel. The software is designed to wake up the system to search for a tag as quickly as possible, and then go back to sleep.By only activating the carrier and measure the amplitude of the received signal could determine whether a tag is around or not. This made it possible to conduct a search for a tag of less than 4 µS.