Electronics For You - - Con­struc­tion -

has to be parked, the RFID tag is placed near the RFID reader, which is in­stalled near the en­try gate of the park­ing lot. As soon as the RFID tag is read by the reader, the sys­tem au­to­mat­i­cally deducts the spec­i­fied amount from the RFID tag and the en­try gate boomer opens to al­low the car in­side the park­ing area. At the same time, the park­ing counter in­cre­ments by one. Sim­i­larly, the door is opened at the exit gate and the park­ing counter decre­mented.

The sys­tem also of­fers the fa­cil­ity to recharge the amount for each RFID tag. No man­ual pro­cess­ing is in­volved. In ad­di­tion, the sys­tem pro­vides se­cu­rity.

Cir­cuit de­scrip­tion

Fig. 5 shows the cir­cuit of the RFIDbased au­to­matic ve­hi­cle park­ing sys­tem. The cir­cuit can be di­vided into dif­fer­ent sec­tions:

Power sup­ply.

Con­nec­tor CON1 (re­fer Fig. 8), diodes D1 through D4, ca­pac­i­tor C1, and volt­age reg­u­la­tor ICS 7805 (IC1) and 7812 (IC2) form the power sup­ply sec­tion of the au­to­matic ve­hi­cle park­ing sys­tem. CON1 is a three­pin con­nec­tor that pro­vides 15V AC or DC power sup­ply to the cir­cuit. In case of 15V AC, diodes D1 through D4 form a bridge rec­ti­fier to rec­tify the AC sup­ply. Ca­pac­i­tor C1 fil­ters out the rip­ples from the rec­ti­fied out­put. ICS 7805 and 7812 pro­vide reg­u­lated +5V and +12V, re­spec­tively, to the cir­cuit. +5V is used to op­er­ate the mi­cro­con­troller, LCD, RFID and IR sen­sor cir­cuit and +12V op­er­ates the mo­tor.

AT89S52 mi­cro­con­troller. AT89S52 is a low­power, high­per­for­mance CMOS 8­bit mi­cro­con­troller with 8kb Flash me­mory. It is com­pat­i­ble with the in­dus­try­stan­dard 80C51 in­struc­tion set and pin­out. The on­chip Flash al­lows the pro­gram me­mory to be re­pro­grammed in­sys­tem or by a con­ven­tional non­volatile me­mory pro­gram­mer. Other fea­tures in­clude 256 bytes of RAM, 32 in­put/out­put lines, watch­dog timer, two data point­ers, three 16­bit timers/coun­ters, a six­vec­tor two­level in­ter­rupt ar­chi­tec­ture, a full­du­plex se­rial port, on­chip os­cil­la­tor and clock cir­cuitry.

Con­nec­tors CON2 through CON4. CON2 and CON3 are two­pin con­nec­tors that con­nect the 12V DC mo­tors to the cir­cuit for con­trol­ling the en­try and exit gate boomers. CON4 is a ten­pin dual­in­line fe­male con­nec­tor that con­nects the RFID reader mod­ule to the cir­cuit.

L293D mo­tor driver. H­bridge DC mo­tor driver L293D (IC5) op­er­ates the DC mo­tors to open the door or bar­rier for en­try into and exit from the park­ing lot. Two high­cur­rent mo­tor driv­ers can be used in place of L293D and 12V DC mo­tors to con­trol the en­try and

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