This chapter contains the block diagram description, hardware and software constituents of the Traffic congestion alert system using GSM project. Also explains the working and implementation of this project with an example.

The Block Diagram includes transmitter and receiver as shown in Figure 2.1, which gives an overall description of the project. Using GSM system the data is transferred from the transmitter to the receiver. This data will be displayed on both the LCD screens placed at transmitting and receiving side.

2.1 TRANSMITTER AND RECEIVER

Figure 2.1 Block Diagram

Sensors are kept on lanes for traffic monitoring. The output of these sensors is given to the PIC16F877A microcontroller. The controller processes these outputs received and the corresponding busy lane is displayed BUSY on the LCD screen connected to the microcontroller. The BUSY message is wirelessly transmitted to the receiving end using the GSM modem. It is processed in the PIC microcontroller.

2.2 HARDWARE DESCRIPTION

The hardware includes power supply, sensors, PIC microcontroller, LCD screen, MAX232, RS232 and GSM modem.

2.2.1 POWER SUPPLY

Figure 2.2 shows ac to dc converter which is used for powering the microcontroller section and relay driving sensor section. These two transformers are used to step down the 230V ac main supply to 12V ac supply. Current handling capacity of the transformer is 500mA.

The 12V ac output is given at the power supply regulation stage. It consists of bridge rectifier using diode D1 to D4 of 1N4007. The current handling capacity of this diode is 1A and voltage handling capacity is 1000V. These 4 diodes are used to rectify the low voltage, i.e. 12V ac into 12V dc.

The output of this stage is given to the capacitor to remove electro-magnetic induction noises. IC 7805 is used to regulate the unregulated dc power. Current carrying capacity of this IC is 1A.

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