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How to Interface RF433.92MHz with 8051 Advanced Development Board

8051 Advanced Development board

The 8051 Advanced Development 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 Advanced Development 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.






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 4-way 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:



Receiver Section:


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

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Title : Program to transmitting and receiving data using RF433.92MHz range.

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#include <reg51.h> #include <stdio.h> #define DATA P1 //Define control pins sbit RS = P3^4; //Register Select sbit RW = P3^5; //LCD Read/Write sbit lcd_e = P3^6; //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); //2x16 Character 5x7 dot DelayMs(15); //matrix LCD,8-bit format lcd_cmd(0x0c); //Display On, cursor off DelayMs(15); lcd_cmd(0x06); //Shift Cursor to right DelayMs(15); lcd_cmd(0x01); //Clear display screen DelayMs(15); //------------------------------------------- // First Line Message Display //------------------------------------------- lcd_cmd(0x80); //First Line Initialization DelayMs(35); i=0; while(msg[i]!='\0') { lcd_display(msg[i]); i++; } DelayMs(50); //------------------------------------------- // Second Line Message Display //------------------------------------------- lcd_cmd(0xc0); //Second Line Initialization DelayMs(35); i=0; while(msg1[i]!='\0') { lcd_display(msg1[i]); i++; } DelayMs(50); } 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; }