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RF module code

 
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jack// ani
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RF module code
PostPosted: Sat Nov 12, 2005 1:05 am     Reply with quote
Hi all,

I need codes for data transmission....between PIC uC, connected to 433MHz RF module. Basically I want to control a motor...the Tx module will send the commands and RX will act accordingly. Please help me......

Thanks a lot
specialk



Joined: 12 Nov 2005
Posts: 27

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PostPosted: Sat Nov 12, 2005 5:11 pm     Reply with quote
Look up "manchester encoding" to find information on wireless data transmissions.

-special [k]
jack// ani
Guest
PostPosted: Mon Nov 14, 2005 11:13 am     Reply with quote
Thanks......I cannot get any well working codes. I'll appreciate a lot if anyone could please share his codes here.....please.

thanks a lot
newguy



Joined: 24 Jun 2004
Posts: 1909

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PostPosted: Mon Nov 14, 2005 12:03 pm     Reply with quote
http://www.ccsinfo.com/forum/viewtopic.php?t=23953
jack// ani
Guest
PostPosted: Tue Nov 15, 2005 9:44 am     Reply with quote
Hi newguy,

Thanks for that. I understood whole of the codes....except two of these lines....please explain its purpose

valid_data_count = 0xff; // get ready to count the number of data bytes - we know we have to expect 5 (Rocks)

and

if (got_id && ++valid_data_count == 5)

thanks

Source code for the reciever is.....

Code:


#include <18F8621.h>
#device *=16 ADC=8
#define Fosc 40000000
#define WireTX PIN_C6
#define WireRX PIN_C7
#define ConsTX PIN_G1
#define ConsRX PIN_G2
#use delay(clock = Fosc,RESTART_WDT)
#fuses EC_IO, BROWNOUT, BORV20, PUT, STVREN, NOLVP
#use rs232(baud=9600, xmit=WireTX, rcv=WireRX, ERRORS, STREAM=Wireless)
#use rs232(baud=9600, xmit=ConsTX, rcv=ConsRX, ERRORS, STREAM=Console)             //Setup RS232

#define RX_BUFFER_SIZE 80
#define TX_BUFFER_SIZE 80

int8 rx_wr_index = 0, tx_rd_index = 0, tx_wr_index = 0, tx_counter = 0, received = 0;
int8 lock_state = 0, rxd, i, valid_data_count;
unsigned int8 rx_buffer[RX_BUFFER_SIZE + 1], tx_buffer[TX_BUFFER_SIZE + 1];
int1 data_avail = FALSE, got_id = FALSE;

#int_RDA
void RDA_isr(void) {
   rx_buffer[rx_wr_index] = getc();
   rxd = rx_buffer[rx_wr_index]; // this just makes it easier typing-wise later on
   rx_wr_index++;
   if (rx_wr_index > RX_BUFFER_SIZE) {
      rx_wr_index = 0;
   }
   
   // now look for unique ID: "Dave "
   if (rxd == 'D' && lock_state == 0) {
      lock_state++;
   }
   else if (rxd == 'a' && lock_state == 1) {
      lock_state++;
   }
   else if (rxd == 'v' && lock_state == 2) {
      lock_state++;
   }
   else if (rxd == 'e' && lock_state == 3) {
      lock_state++;
   }
   else if (rxd == ' ' && lock_state == 4) { // got the entire string "Dave ", in that order
      lock_state = 0; // reset our "combination lock"
      got_id = TRUE;
      valid_data_count = 0xff; // get ready to count the number of data bytes - we know we have to expect 5 (Rocks)
      // also going to reset the buffer write index back to 0, so that I know where my valid data will be
      rx_wr_index = 0;
   }
   else { // we didn't receive "Dave ", so reset the lock back to the beginning
      lock_state = 0;
   }
   
   if (got_id && ++valid_data_count == 5) {
      data_avail = TRUE;
      got_id = FALSE;
   }
}

#int_TBE
void TBE_isr(void) {
   if (tx_counter != 0) {
      putc(tx_buffer[tx_rd_index]);
      if (++tx_rd_index > TX_BUFFER_SIZE) {
         tx_rd_index = 0;
      }
      tx_counter--;
      if (tx_counter == 0) {
         disable_interrupts(INT_TBE);
      }
   }
}

void bputc(int c) {
   int restart = 0;

   while (tx_counter > (TX_BUFFER_SIZE - 1));

   if (tx_counter == 0) {
      restart = 1;
   }
   tx_buffer[tx_wr_index++] = c;
   if (tx_wr_index > TX_BUFFER_SIZE) {
      tx_wr_index = 0;
   }
   tx_counter++;
   if (restart == 1) {
      enable_interrupts(INT_TBE);
   }
}

void main() {

   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_psp(PSP_DISABLED);
   setup_spi(FALSE);
   setup_wdt(WDT_ON);
   setup_timer_0(RTCC_INTERNAL|RTCC_OFF|RTCC_8_bit);
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);
   setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
   enable_interrupts(INT_RDA);
   //enable_interrupts(INT_TBE);
   enable_interrupts(global);

   set_tris_e(0);
   fprintf(Console,"working");
   while (TRUE) {
      restart_wdt();
      if (data_avail) {
         data_avail = FALSE;
         fprintf(Console,"\r\n\r\nData is now available\r\nData: ");
         for (i = 0; i < 5; i++) {
            fprintf(Console,"%c",rx_buffer[i]);
         }
      }
   }
}

newguy



Joined: 24 Jun 2004
Posts: 1909

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PostPosted: Tue Nov 15, 2005 10:08 am     Reply with quote
jack// ani wrote:
Hi newguy,

Thanks for that. I understood whole of the codes....except two of these lines....please explain its purpose

valid_data_count = 0xff; // get ready to count the number of data bytes - we know we have to expect 5 (Rocks)

and

if (got_id && ++valid_data_count == 5)

thanks



valid_data_count is what its name implies, just a count of the valid characters. In this simple example, the valid data is "Rocks" (minus the quotes). I initially set valid_data_count to 0xff, which is 255 because valid_data_count is an 8 bit integer.

Now the next line, if (got_id && ++valid_data_count == 5) executes. got_id is now true, and "++valid_data_count" means first increment valid_data_count (255 wraps to 0), and then check to see if the new value of valid_data_count is equal to 5. If both of these conditions are true, we've received the 5 bytes of the message we're expecting.

Now that I think of it, it is quite confusing. Would it help if I told you that you can change valid_data_count to be initialized to 0 (instead of 255), and change the "== 5" to "== 6". Might be a bit easier to follow.

Hope this helps.
jack// ani
Guest
PostPosted: Tue Nov 15, 2005 2:51 pm     Reply with quote
Thanks a lot.......you are very helpful. I really appreciate it a lot.

thanks again
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