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Help!! SPI conn between 2 PICs

 
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Help!! SPI conn between 2 PICs
PostPosted: Wed Aug 23, 2006 6:46 pm     Reply with quote

I am working on a SPI communication between 2 PICs

18F452 is Master
16F873 is Slave

I have the master code working, but I can not get the slave to work. I know master code is working because I have an Assembler code per MICROCHIP SPI tutorial in the slave. Confirmed that work, but I want to have it in CCS C instead of assembler.

How to get the data from the master?

CAn any body helP?

Here is my code:





Slave Code:

Code:

/*
//*********************
Example code demonstrates SPI connection between 2 PICs (18F452
and 16F876).
Master sends data (a counter), Slave receives and outputs to
LEDs on PORTB

//********************************************************************
*/


#include <16F873.h>
#fuses XT,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7) 

int data;

void main()
{
   
   //Ports Initialization
   set_tris_a(0x3F);            // PORTA to inputs
   set_tris_b(0x00);            // PORTB to outputs
   set_tris_c(0x18);            //Set SDO to output, SCK &  SDI to input


   setup_ADC_ports(NO_ANALOGS);   //Turn off A/D ports, all
                           //porta will be use as digital   
   
   //SPI configuration
   setup_spi(spi_slave | spi_h_to_l | spi_clk_div_16);


   while(1)
   {
         
      
      // Test to see if data transfer complete?
      if(!input(PIN_A5));

      //Get data
      data = spi_read();
      

      output_b(data);

   


   }

}



Here is the Master Code:


Code:

/*
//*********************

Example code demonstrates SPI connection between 2 PICs (18F452
and 16F876).
Master sends data (a counter), Slave receives and outputs to
LEDs on PORTB

//********************************************************************
*/


#include <18F452.h>
#fuses XT,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7) 


//Defined Chip Select PIN
#define SS   PIN_A2

//Global Variables
int counter,data;

void main()
{
   //Reset counter to 0
   counter = 0;

   //Ports Initialization
   set_tris_a(0x00);            // PORTA to outputs
   set_tris_c(0x10);            //Set SCK & SDO to output & SDI to input


   setup_ADC_ports(NO_ANALOGS);   //Turn off A/D ports, all
                           //porta will be use as digital   
   
   //SPI configuration
   setup_spi(spi_master | spi_h_to_l | spi_clk_div_16);


   while(1)
   {
      //Enable Chip Select pin (LOW)
      output_low(SS);

      //Send Data (counter) to Slave      
      spi_write(counter);

      // Test to see if data transfer complete?
      while(!spi_data_is_in());

      //get data (does not use at this time    
      data=spi_read();

      //Disable Chip Select PIN (HIGH)   
      output_high(SS);   
      
      //Update counter
      counter ++;

      //Delay routine so human eyes can see the flash
      Delay_ms(100);


   }

}


Please help...
Guest








PostPosted: Wed Aug 23, 2006 7:03 pm     Reply with quote

By the way just to clear, the comment said that I use the 876 but actually

I do use the 16F873 as the slave
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Aug 23, 2006 7:14 pm     Reply with quote

Sample code for SPI slave:
http://www.ccsinfo.com/forum/viewtopic.php?t=26888
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