Networking of Multiple street junction signals for better traffic management Submitted by:

contents Introduction Block diagram Power supply PIC Microcontroller CAN protocol Schematic & Working of the project Advantages Applications Future scope Conclusion

Project overview More and more microcontrollers are embedded in a large area of products from industrial to domestic domains. A good example is the automobile, a modern one containing tens of microcontrollers. As their number increased the communication between them became necessary. The serial solution was preferred and a lot of serial buses and protocols were developed optimizing different parameters of the communication.

Contd.. Several examples are: RS232, LIN, and SPI, CAN and so on. Monitoring serial communications is necessary for creating virtual transfer partners, and in testing and debugging phases. The paper describes a message based monitoring tool using the RS232 Rx Tx features of the MC to communicate between 3 PIC MCs for keeping track the traffic movements of the previous junction with synchronization and changing the red signal to green so that a passing vehicle mostly gets green signal which results in least traffic jam.

Block diagram

Power supply Step down transformer Bridge rectifier Filter Regulator

Contd.. The 230V AC supply is first stepped down to 12V AC using a step down transformer. This is then converted to DC using bridge rectifier. The AC ripples is filtered out by using a capacitor and given to the input pin of voltage regulator 7805. At output pin of this regulator we get a constant 5V DC which is used for MC and other ICs in this project.

PIC (PIC16F877A) High-Performance RISC CPU: Only 35 single-word instructions. All single-cycle instructions except for program branches, which are two cycle. Operating speed: DC – 20 MHz clock input DC – 200 ns instruction cycle Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes of Data Memory (RAM), Up to 256 x 8 bytes of EEPROM Data Memory. Pin out compatible to other 28-pin or 40/44-pin, PIC16CXXX and PIC16FXXX microcontrollers.

Special Microcontroller Features: 100,000 erase/write cycle Enhanced Flash program memory typical. 1,000,000 erase/write cycle Data EEPROM memory typical. Data EEPROM Retention > 40 years. Self-reprogrammable under software control. In-Circuit Serial Programming™ (ICSP™) via two pins. Single-supply 5V In-Circuit Serial Programming. Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation. Programmable code protection. Power saving Sleep mode. Selectable oscillator options. In-Circuit Debug (ICD) via two pins.

Peripheral Features: Timer0: 8-bit timer/counter with 8-bit prescaler. Timer1: 16-bit timer/counter with prescaler, can be incremented during Sleep via external crystal/clock. Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler. Two Capture, Compare, PWM modules - Capture is 16-bit, max. resolution is 12.5 ns - Compare is 16-bit, max. resolution is 200 ns - PWM max resolution is 10-bit Synchronous Serial Port (SSP) with SPI™ (Master mode) and I2C™ (Master/Slave). Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9-bit address detection. Parallel Slave Port (PSP) – 8 bits wide with external RD, WR and CS controls (40/44-pin only). Brown-out detection circuitry for Brown-out Reset (BOR).

PIN DIAGRAM OF PIC16F877

CAN Protocol Controller–area network (CAN or CAN-bus) is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer. CAN is a message based protocol, designed specifically for automotive applications but now also used in other areas such as industrial automation and medical equipment. Development of the CAN-bus started originally in 1983 at Robert Bosch GmbH the protocol was officially released in 1986 at the Society of Automotive Engineers (SAE) congress in Detroit, Michigan.

Contd.. The CAN bus may be used in vehicles to connect engine control unit and transmission, or (on a different bus) to connect the door locks, climate control, seat control, etc. Today the CAN bus is also used as a field bus in general automation environments; primarily due to the low cost of some CAN Controllers and processors.

Working of project The project uses 3MC’s for three traffic junctions. Red, Yellow, Green combination of LED’s represents a signal light set. Four such sets are fed from the respective MC through series resistors for current limiting purposes. Other 2 junctions similarly have identical connections for the LED’s. The junction 1 that manages the signal lights from U1 delivers at its output port 3.1 used as transmit pin.

Contd.. The data so transmitted that contains the desired delay time information appears at port 3.0 of MC U2 being the received data to enable the green light operation accordingly. Simultaneously the data transmitted from “U2 port 3.1 of pin 11 is fed to the received pin of “U3” port 3.0 which is kept ready for the green signal to follow through such that the moving vehicle gets green signal by the time it reaches the third junction duly managed by “U3” thus a moving vehicle starting from “U1” passes through “U2” & “U3” uninterrupted facing green signal all through.