This document outlines a project designed to develop a library book locator system that utilizes a PC for operation. It details the hardware and software components involved, including the use of microcontroller interfacing, RS232 communication, and various integrated circuits for data encoding and decoding. The document includes code snippets for controlling the communication and operations of the project.

2. LIBRARY BOOK
LOCATOR
We all might have
experienced some
difficulty in locating a
specific book in a
library. This project
aims to develop a
system used to locate
a particular book in a
library with the help
of a PC.

8.  ORG 0000H
 MOV TMOD,#20H ; Timer 1 in mode 2 “8 bit auto reload”
 MOV TH1,#-3 ; Set baud rate as 9600
 MOV SCON,#50H ; Mode 1, Receive Enable=1
 SETB TR1 ; Start timer 1
 HERE:JNB RI,HERE ; Waiting for data to reach SBUF register
 MOV A,SBUF ; Moving the data received to the acc
 MOV P1,A ; Moving the data to Port 1
 CLR RI ; Receive Interrupt Flag = 0

 SJMP HERE ; Infinite loop
 END

9.  • RS232 is not compatible to TTL. For this
reason, to connect any RS232 to a
microcontroller system, we must use “Voltage
Converters” such as MAX232 to convert the
 TTL logic levels to the RS232 voltage levels,
and vice versa.
 • MAX232 IC chips is referred to as “Line
Driver”.

10.  The parallel data obtained from the
Microcontroller AT 89C51 Ports is transferred
to the encoder IC HT12E
 The HT12E encoder converts this parallel data
into serial data which is then transmitted via
the ASK transmitter.

13.  ASK Receiver module receives the data
transmitted by the ASK Transmitter and
transfers this serial data to the HT12D decoder
IC.
 HT12D decoder IC converts the serial data into
4 bit parallel data.
 This 4 bit parallel data is further fed into a 4:16
decoder IC CD 4514 to get 16 parallel outputs.

16.  Private Declare Sub Sleep Lib "kernel32" (ByVal dw Milliseconds
As Long)
 ' Form load code
Private Sub FormLoad()
MSComm1.Settings = "9600,N,8,1" „ Operation at 9600 baud
MSComm1.CommPort = 1 ‟ Change to the available
comm port on your PC
MSComm1.PortOpen = True „ Opens communication port
End Sub
 ' Used for the "pause"
Public Sub Pause(milli As Long)
Sleep (milli)
End Sub

17.  ' Button 1 code. Sends synch byte of 170, a receiver address of "0", then turns OFF all
outputs on receiver.
Private Sub Command1_Click()
For I = 1 To 4 ' Loop 4 times
MSComm1.Output = Chr$(170) & Chr$(0) & Chr$(0)
Pause 250 ' Pause 250mS
Next I
End Sub
.
.
.
 ' Button 16 code. Sends synch byte of 170, a receiver address of "0", then turns ON output
all outputs on receiver.
Private Sub Command16_Click()
For I = 1 To 4 ' Loop 4 times
MSComm1.Output = Chr$(170) & Chr$(0) & Chr$(15)
Pause 250 ' Pause 250mS
Next I
End Sub

18. Private Sub Command17_Click()
If MSComm2.PortOpen = True Then MSComm2.PortOpen = False
End If
End
End Sub