spi with 2 Pic

[franck]

I try to make an interface spi with 2 Pic but that does not function. Is what somebody can help me please?


Here my code.



// SDO bit 5 patte 24 RC5
// CLK bit 3 patte 18 RC3
// SDI bit 4 patte 23 RC4


//*********************** includes and uses....***********************************/

#include <sk18f4x2.h>
#include <sk4x2_driver_lcd.c>
#include <sw_anti_rebond.c>

#use delay (clock=10000000) // 10MHz pour l'emulation et 10 MHz pour la programmation


// fuses pour programmation définitive
#fuses HS, NOPROTECT, NOOSCSEN, BROWNOUT, NOWDT, BORV27, PUT, CCP2C1, STVREN, NODEBUG, NOLVP, NOWRT, NOWRTD, NOWRTB, NOWRTC, NOCPD, NOCPB, NOEBTR, NOEBTRB




//************************************************************************************************************************************************
//
//
//Initialisation
//
//************************************************************************************************************************
u_switch sw_ok, sw_menu_esc, sw_plus, sw_minus;
byte string1[] = "Bonjour";




// comme on doit manipuler les bits, il faut également pouvoir y accéder par un word
// enfin, le format est en entier signé, if faut donc également pouvoir y accéder par un signed int
typedef union {
struct
{
byte lsb;
byte msb;
byte Cmd;
} Comd_Addr;

int8 Protocole;
} t_module;
t_module module; //byte a envoyer au slave





//******************************************Routine Timer 0 *****************************************************************************
// *****************************
// fonction de gestion de l'interruption du timer 0
//*******************************
#INT_TIMER0
interruption_timer0()
{
set_timer0(0xfe70); // pour 10ms : 10ms/
sw_ok.bits.valeur_lue = input(PIN_B3);
sw_anti_rebond (&sw_ok);
sw_menu_esc.bits.valeur_lue = input(PIN_B0);
sw_anti_rebond (&sw_menu_esc);
sw_plus.bits.valeur_lue = input(PIN_B1);
sw_anti_rebond (&sw_plus);
sw_minus.bits.valeur_lue = input(PIN_B2);
sw_anti_rebond (&sw_minus);
}





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





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


void Master()


{
setup_spi(spi_master |spi_h_to_l |spi_clk_div_64 );

//while( !spi_data_is_in() )

{

SPI_WRITE (0x01);
SPI_WRITE (0x02);
SPI_WRITE (0x03);

module.comd_addr.lsb=spi_read();
module.comd_addr.cmd=spi_read();
module.comd_addr.msb=spi_read();


}



}

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

void slave()


{


setup_spi(SPI_SLAVE|SPI_SS_DISABLED|spi_l_to_h |spi_clk_div_64 );


while( !spi_data_is_in() )

{


module.comd_addr.lsb=spi_read();
module.comd_addr.cmd=spi_read();
module.comd_addr.msb=spi_read();

output_high(PIN_E2);




}



}


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

void main()

{


setup_timer_0 (RTCC_INTERNAL | RTCC_DIV_1);
// pour 10ms : 0-(10ms/100ns/4) = 0-400 = 0-0x190 = 0xfe70
set_timer0(0xfe70); // pour 10ms
enable_interrupts(INT_TIMER0);
enable_interrupts(global);



sw_init_struct(&sw_ok);
sw_init_struct(&sw_menu_esc);
sw_init_struct(&sw_plus);
sw_init_struct(&sw_minus);



while(1)
{
if (sw_menu_esc.bits.juste_presse == true)

{
if (sw_menu_esc.bits.toggle == true)

{
Master();

}
}


if (sw_plus.bits.juste_presse == true)

{
if (sw_plus.bits.toggle == true)

{
slave();
// output_high(PIN_E2);
}
}
}
}

[ckielstra]

The most obvious mistake:

[Ttelmah]

Also remember that the SDO line of each chip must connect to the SDI line of the other, while the SCLK line goes straight across.
As written, I can't quite see how it is going to work. You have to remember that SPI, is a bi-directional interface. You write three bytes with the master, then try to read three bytes. Each 'write', transfers a byte _in both directions_. When you write a byte to the slave, the byte already sitting in the slaves SPI data register, will be clocked 'back' at the same time. Hence when you send '1', you will get back any data 'left' sitting in the register. Then when you send '2', you will get back the '1' that was sent last time (since the slave has not written any return data). This will happen to the third byte. spi_read, without a value, wil retrieve the value in the register, if one is waiting, and just sit, if one is not.
Then you try to 'read'. The register at this point will contain '2', and this will be returned for the first read. The master will then sit trying to read, and get nowhere (it after all, controls the bus, and you are asking it to read more data that does not yet exist...).
The sequence should be:

[Cheick]

that made 2 months that I is caught the head with spi I seek the explanation of spi mode with two pic there are somebody to help me?