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1. Introduction:-
This Project will turn on the lights of the room automatically when a first person comes in the room and will turn off the lights when last person leave the room.
2. Working:-
In this project we are using Microcontroller board, Relay board, LCD, Buzzer, Power supply board and LDR based two counter sensors(one for in counter and second for out counter).
In this project our in counter sensor is placed outside from the gate and out counter sensor is placed inside the room. When first person enters in the room firstly it passes through the in counter sensor and then out counter sensor, these sensor gives the signal to our microcontroller and as soon as our microcontroller gets the signal, it on the relay and our room lights will turn on through the relay board.
Similarly when the persons leave the room, they are also sensed by the sensor and when the last person leaves the room, our microcontroller get signal from the sensors and it will turn off the room light through relay board.
These sensors also do one more thing that they count the no. of persons come in the room and shows the count on LCD means we can see on the LCD that how many persons are in the room.
The programming of the microcontroller will be done in Embedded C using “Keil uv3 IDE”. For programming, Philip’s flasher tool “Flash Magic” will be used.
3. Block Diagram:
Block Diagram
For this project NXP’s P89V51RD2 microcontroller will be used, it is an 8 bit 8051 based microcontroller that has ISP (In System Programming) capability. The Microcontroller can be programmed by PC through RS232.
4. Technical Description
4.1 P89V51RD2 Microcontroller:
The P89V51RD2 is an 80C51 microcontroller with 64 kB Flash and 1024 bytes of data RAM.
A key feature of the P89V51RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate (12 clocks per machine cycle) or select the X2 mode (6 clocks per machine cycle) to achieve twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance by reducing the clock frequency by half, thus dramatically reducing the EMI.
The Flash program memory supports both parallel programming and in serial In-System Programming (ISP). Parallel programming mode offers gang-programming at high speed, reducing programming costs and time to market. ISP allows a device to be reprogrammed in the end product under software control. The capability to field/update the application firmware makes a wide range of applications possible.
The P89V51RD2 is also In-Application Programmable (IAP), allowing the Flash program memory to be reconfigured even while the application is running.
4.1.1 Features of the P89V51RD2
• 80C51 Central Processing Unit
• 5 V Operating voltage from 0 to 40 MHz
• 64 kB of on chip Flash program memory with ISP (In System Programming) and IAP (In-Application Programming)
• Supports 12-clock (default) or 6-clock mode selection via software or ISP
• SPI (Serial Peripheral Interface) and enhanced UART
• PCA (Programmable Counter Array) with PWM and Capture/Compare functions
• Four 8-bit I/O ports with three high-current Port 1 pins (16 mA each)
• Three 16-bit timers/counters
• Programmable Watchdog timer (WDT)
• Eight interrupt sources with four priority levels
• Second DPTR register
• Low EMI mode (ALE inhibit)
• TTL- and CMOS-compatible logic levels
• Brown-out detection
• Low power modes
o Power-down mode with external interrupt wake-up
o Idle mode
• PDIP40, PLCC44 and TQFP44 packages
4.1.2 8051 Block Diagram:
4.1.3 Memory organization
The device has separate address spaces for program and data memory.
Flash program memory
There are two internal flash memory blocks in the device. Block 0 has 64 kbytes and contains the user’s code. Block 1 contains the Philips-provided ISP/IAP routines and may be enabled such that it overlays the first 8 kbytes of the user code memory.
The 64 kB Block 0 is organized as 512 sectors, each sector consists of 128 bytes.
Access to the IAP routines may be enabled by clearing the BSEL bit in the FCF register. However, caution must be taken when dynamically changing the BSEL bit. Since this will cause different physical memory to be mapped to the logical program address space, the user must avoid clearing the BSEL bit when executing user code within the address range 0000H to 1FFFH.
Data RAM memory
The data RAM has 1024 bytes of internal memory. The device can also address up to 64 kB for external data memory.
Expanded data RAM addressing
The P89V51RD2 has 1 kB of RAM. The device has four sections of internal data memory:
1. The lower 128 bytes of RAM (00H to 7FH) are directly and indirectly addressable.
2. The higher 128 bytes of RAM (80H to FFH) are indirectly addressable.
3. The special function registers (80H to FFH) are directly addressable only.
4. The expanded RAM of 768 bytes (00H to 2FFH) is indirectly addressable by the move external instruction (MOVX) and clearing the EXTRAM bit.
4.2 Serial Communication:
In telecommunication and computer science, serial communication is the process of sending data one bit at one time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent together, on a page link with several parallel channels. Serial communication is used for all long-haul communication and most computer networks, where the cost of cable and synchronization difficulties makes parallel communication impractical. At shorter distances, serial computer buses are becoming more common because of a tipping point where the disadvantages of parallel buses (clock skew, interconnect density) outweigh their advantage of simplicity (no need for serializer and deserializer (SERDES)). Improved technology to ensure signal integrity and to transmit and receive at a sufficiently high speed per lane has made serial links competitive.
A parallel port sends and receives data eight bits at a time over 8 separate wires. This allows data to be transferred very quickly; however, the cable required is more bulky because of the number of individual wires it must contain. Parallel ports are typically used to connect a PC to a printer and are rarely used for much else. A serial port sends and receives data one bit at a time over one wire. While it takes eight times as long to transfer each byte of data this way, only a few wires are required. In fact, two-way (full duplex) communications is possible with only three separate wires - one to send, one to receive, and a common signal ground wire.
4.2.1 Bi-Directional Communications
The serial port on your PC is a full-duplex device meaning that it can send and receive data at the same time. In order to be able to do this, it uses separate lines for transmitting and receiving data. Some types of serial devices support only one-way communications and therefore use only two wires in the cable - the transmit line and the signal ground.