EXPERIMENTAL RESULT

TRANSMITTER SENDING THE DATA

RECEIVER RECEIVE THE DATA

From the figure it shows that transmitter and receiver can send signal and receive the signal up to 4 bits. In figure 18 the transmitter send signal 3 bits (b) and receiver in figure 19 receive the bits same as transmitter sent signal. While waveform in ‘a’ its reserve for address (8 bits). When address transmitter 00000000 bits, address receiver also must 00000000 bits.  

RESULT AND ANALYSIS

EXPERIMENTAL ANALYSIS

Relationship of voltage supply and resistor (frequency encoder and decoder)

Supply voltage	(KHz)	Value Resistor (Ω)	Supply voltage	(KHz)	Value Resistor (Ω)
2	3.5	510 K	5	175	43 K
4	4	680 K	5	200	36 K
6	4	750 K	5	200	36 K
8	4.125	750 K	5	206.25	33 K
10	5	620 K	5	250	27 K
12	1.625	2 M	5	81.5	100 K

RS 232 SERIAL COMMUNICATION

SCI is an abbreviation for Serial Communication Interface and, as a special subsystem of microcontroller PIC16F877A. It provides RS232 serial communication with PC easily. As with hardware communication, use standard NRZ (Non Return to Zero) format also known as 8 (9)-N-1, or 8 or 9 data bits, without parity bit and with one stop bit. Free line is defined as the status of logic one. Start of transmission - Start Bit, has the status of logic zero. The data bits follow the start bit (the first bit is the low significant bit), and after the bits we place the Stop Bit of logic one. The duration of the stop bit 'T' depends on the transmission rate and is adjusted according to the needs of the transmission. For the transmission speed of 9600 baud, T is 104μs.

In order to connect a microcontroller to a serial port on a computer, need to adjust the level of the signals so communicating can take place. The signal level on a PC is -10V for logic zero, and +10V for logic one. Since the signal level on the microcontroller is +5V for logic one and 0V for logic zero, we need an intermediary stage that will convert the levels. One chip specially designed for this task is MAX232. This chip receives signals from -10 to +10V and converts them into 0 and 5V. The circuit for this interface is shown in the.

ASSEMBLY LANGUAGE

Assembly programming language as it applies to embedded microcontroller applications. This programming needed programmer for declaring variables and constant do loops, testing the logic analyzer. In c programming there are several types of loops. Next, the important part is software to interface with PIC. The software used is assembly programming. Assembly compiler is software to write, simulate and burn the program into PIC.  To ensure written programming worked or not, it can combine with software Proteus. From this software, the program can be simulated with circuit

   VISUAL BASIC LANGUAGE

Normal PC hardware might well run with just T_x, R_x and Ground connected, most driver software will wait forever for one of the handshaking lines to go to the correct level. Depending on the signal state it might sometimes work, other times it might not. The reliable solution is to loop back the handshake lines if they are not used.

MAIN BOARD PROGRAMMING

display1     movf DIGIT,w

                              xorlw A'A'

                              btfss STATUS,Z

                              goto CheckA

                              goto PAS1

CheckA                 movf DIGIT,w

                              xorlw A'B'

                              btfss STATUS,Z

                              goto CheckB

                              goto PAS2

CheckB                 call Insert                   

This example of programming that have been wrote in MPLAB. This program is activating when key ‘A’ and LCD will display ‘set password 1’. Then this programming is to scan the input have been key in by user. The process is looping 5 times because entered password is 5 bits.