RF Interfacing With 8051 Friendly

8051 HOW-TO GUIDE

Interface RF433.92MHz with 8051

Contents at a Glance

8051 Friendly Board .........................................................3 RF433.92(Radio Frequency) .. Error! Bookmark not defined. RF Transmitter ...................... Error! Bookmark not defined. RF Receiver........................... Error! Bookmark not defined. Circuit Diagram to Interface RF with 8051 ........................5 Source Code ....................................................................5 C Program to RF using 8051 .............................................7

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8051 Friendly Board The 8051 Friendly board is specifically designed to help students to master the required skills in the area of embedded systems. The kit is designed in such way that all the possible features of the microcontroller will be easily used by the students. The kit supports in system programming (ISP) which is done through serial port. NXP’s 8051 (AT89V51RD2), 8051 Friendly Kit is

proposed to smooth the progress of developing and debugging of various designs encompassing of speed 8-bit Microcontrollers.

RF433.92MHz (Radio Frequency): Radio Frequency, any frequency within the electromagnetic spectrum associated with radio wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space. Many wireless technologies are based on RF field propagation.


Receiver Module

Transmitter Module

RF transmitter: RF433.92MHz transmitter Module conneted with 4-bit encoder, user can evaluated RF interface in two ways (Standalone without MCU, user can give inputs through 4way DIP switchSW35) while making switch SW35 to ON positions inputs low goes to the encoder. Data will transmit through the module. Also provided to configure address lines of the encoder.

RF Receiver: RF433.92MHz Receiver Module connected with 4-bit decoder, user can evaluated RF signal with the help of LED indications. Whenever receives data through transmitter VT LED, indicates for valid transmission.


Circuit Diagram to RF with 8051 Transmitter Section:

TX Module

Ant

2 1 P J 1 2 3 4

1 1

C16 0.1D D 10 SW34

LED

R 49 330 E RF_P

U18 1 2 3 4 5 6 7 8 9

A0 A1 A2 A3 A4 A5 A6 A7 Vss

Vdd Dout Osc1 Osc2 TE D11 D10 D9 D8

18 17 16 15 14 13 12 11 10

RF_P

SW35 TX_D3 TX_D2 TX_D1 TX_D0

R51 750K TX_D3 TX_D2 TX_D1 TX_D0

SW DIP-4

D 11

LED

R 50 330 E

D 12

LED

R 52 330 E

D 13

LED

R 53 330 E

SW DIP-8 HT-12E


Receiver Section:

D14 LED R54 330E

RF_P

1

R55 1K C17 0.1D

SW36

BC547 2

Q5

3

JP13 Rx Module

U19 1 2 3 4 5 6 7 8 9

A0 A1 A2 A3 A4 A5 A6 A7 Vss

Vdd VT Osc1 Osc2 DIN D11 D10 D9 D8

18 17 16 15 14 13 12 11 10

RF_P R56 33K DATAIN RX_D3 RX_D2 RX_D1 RX_D0

Ant D 15

LED

R 57 330E

0 1 2 3 4 5 6 7 1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1

1

RF_P 1

D 16

LED

R 58 330E

D 17

LED

R 59 330E

D 18

LED

R 60 330E

SW DIP-8 HT-12D

N I A T A D

RF_P

Source Code The Interfacing RF with 8051 program is very simple and straight forward that uses a transmitting and receiving data. In C programs you cannot be sure of delay, because it depends on compiler how it optimizes the loops as soon as you make changes in the options the delay changes.


C Program to RF using 8051 *************************************************************************************** Title : Program to transmitting and receiving data using RF433.92MHz range. *************************************************************************************** #include #include #define DATA P1 //Define control pins sbit RS = P3^4; sbit RW = P3^5; sbit lcd_e = P3^6;

//Register Select //LCD Read/Write //LCD Enable

sbit EXINT0 = P3^2; sbit EXINT1 = P3^3; Code unsigned char msg[] = (" FRINDLY 8051 "); //Display the message Code unsigned char msg1[] = ("RF 433MHz COMM.."); Unsigned char U_N, L_N, Word, Cnt=0; Unsigned char ch,up,lw; Unsigned char curs = 0x80; //---------------------------------// LCD Functions //---------------------------------Void lcd_init(void); Void lcd_cmd(unsigned char); Void lcd_display(unsigned char); Void DelayMs(int);


//---------------------------------// LCD command Function //---------------------------------Void lcd_cmd(unsigned char cmnd) { DATA = cmnd; RS = 0; RW = 0; lcd_e = 1; DelayMs(35); lcd_e = 0; } //---------------------------------// LCD Data Function //---------------------------------Void lcd_display(unsigned char dat) { DATA = dat; RS = 1; RW = 0; lcd_e = 1; DelayMs(35); lcd_e = 0; } //---------------------------------// LCD Delay Function //---------------------------------Void DelayMs(int k) { unsigned int a; for(a=0;a<=k;a++); } //---------------------------------// LCD Initialization //----------------------------------


Void lcd_init(void) { Unsigned char i; lcd_cmd(0x38); DelayMs(15); lcd_cmd(0x0c); DelayMs(15); lcd_cmd(0x06); DelayMs(15); lcd_cmd(0x01); DelayMs(15); //------------------------------------------// First Line Message Display //------------------------------------------lcd_cmd(0x80); DelayMs(35); i=0; While (msg[i]!='\0') { lcd_display(msg[i]); i++; } DelayMs(50); //------------------------------------------// Second Line Message Display //------------------------------------------lcd_cmd(0xc0); DelayMs(35); i=0; While (msg1 [i]! ='\0') { lcd_display(msg1[i]); i++; } DelayMs(50);

//2x16 Character 5x7 dot //matrix LCD,8-bit format //Display On, cursor off //Shift Cursor to right //Clear display screen

//First Line Initialization

//Second Line Initialization


}

Void Serial_Init(void) { TMOD = 0x20; SCON = 0x50; TH1 = 0xFD; TR1 = 1; TI = 1; } Void Recieve (unsigned char Pos) { if (Pos == 0) { L_N = (P2 & 0xF0) >> 4; } else { U_N = (P2 & 0xF0); } } //^^^^^^^^^^^^^^^^^^^^^^^^^^Main Program Starts Here^^^^^^^^^^^^^^^^^^^^^^^^^^ void main(void) { P2 = 0xFF; Serial_Init(); lcd_init(); EA = 1; ES = 1; EX0 = 1; EX1 = 1; while (1)


{ if (Cnt == 1) { lw = 0xF0 | (ch & 0x0F); up = 0xF0 | ((ch & 0xF0)>>4); P2 = lw; DelayMs(220); Recieve (0); P2 = up; DelayMs(200); Recieve (1); Word = U_N | L_N; SBUF = Word; if (curs == 0x90) { curs = 0xC0; } if (curs == 0xD0) { curs = 0x80; } lcd_cmd(curs++); lcd_display(Word); Cnt = 0; P2 = 0xFF; } } } //^^^^^^^^^^^^^^^^^^^^^^^^^^ Serial Interrupt Routine ^^^^^^^^^^^^^^^^^^^^^^^^^^ void Serial_Interr (void) interrupt 4 { if (RI == 1) {


ch = SBUF; if (curs == 0x80) lcd_cmd(0x01); Cnt = 1; } RI = 0; }


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RF Interfacing With 8051 Friendly

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