rnome
Joined: 18 Dec 2006
Posts: 20
Location: europe (Turkey)
|
| RF communication problem (serial) |
 Posted: Thu Sep 20, 2007 9:43 am |
 |
|
hi everybody
i m trying to send 6 bytes via serial
but whatever i done it didnt work correct.
i wrote this codes for reciever side
| Code: | #include <16F877.h>
#use delay(clock=4000000)
#fuses XT,NOWDT,NOPROTECT,NOLVP
#use rs232(baud=2400,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
#include <lcd.c>
int data[6], x;
int1 data_come=0;
int count=0,index=0;
#INT_RDA
void RDA_isr()
{
x=getc();
if(data_come==1){
data[index]=x;
index++;
if(index>=6){
index=0;
data_come=0;
}
}
if(x==85) //85 is preamble
count++; // if one after the other 5 unit 85 come count
else // reaches 5. else count already 0.
count=0;
if(count==5){ //if count equal to 5
count=0; //data_come is set to take datas in a array
data_come=1;
}
}
void main( void )
{
lcd_init();
output_high(pin_d2);
enable_interrupts(int_rda);
enable_interrupts(GLOBAL);
for(;;){
lcd_gotoxy(1,1);
printf(lcd_putc, "%u,%u,%u, \n%u,%u,%u ",data[0],data[1],data[2],data[3],data[4],data[5]);
}
} |
i must follow communication protocol of my RF modules
at first 5 bytes preamble must send to wake up RF hardware
after these 5 bytes i can send my 6 bytes
preamble codes are unimportant and i dont want to take them
and these codes for transmitter
| Code: | #include <16F877.h>
#fuses Xt,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=2400,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)
int d0=10, d1=20, d2=30, d3=40, d4=50, d5=60;
int dizi[6]={10,20,30,40,50,60};
void send()
{int i;
for(i=0;i<5;i++)
{
putc(85); // 5 byte preamble
}
putc(d0); //datas
putc(d1);
putc(d2);
putc(d3);
putc(d4);
putc(d5);
}
void main()
{
output_high(pin_B6);
for(;;)
{
send();
delay_ms(800);
}
} |
_________________
live fast, never rest and do your best |
|
libor
Joined: 14 Dec 2004
Posts: 288
Location: Hungary
|
|
| Posted: Thu Sep 20, 2007 10:10 am |
|
|
At first glance:
A preamble in RF communication should be alternating 0s and 1s, like 0x55. The preamble is used by the receiver module to tune on to the correct datarate.
In your receiver code you rely on receiving the preamble correctly. This is usually not possible, the beginning of the preambles gets lost, this is what they are for.
I think there is a further problem of detecting the byte boundaries correctly. |
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
