SPI beginner

Hello,
No body to help me so i searched on my own and here are the answers :

>>>2)  Datasheets DS39699B says In Standard modes, the SPIxBUF register must not be written before SPIxTBF bit is
>>>set.  Is this true or is this an error ? i thougt .... not to be written while it is set or before it is cleared ?

According to my working code ..... write to SPI2BUF only when  SPI2STATbits.SPITBF  == 0     (DataSheet error ?!)

>>>4) on many examples i see that TRIS registers are used for signals.  I did not notice that in case of PIC24FJ128GA010. So do i have to use >>>TRIS or not ?

According to my working code .....   there is no need to TRIS  the bits


Here is working code on Master side


void SPI2Init(int Mode)
{
    SPI2STATbits.SPIEN = 0;           // Disable SPIx module

    IFS2bits.SPI2IF = 0;                 // Clear SPIx interrupt flag   
    IEC2bits.SPI2IE = 0;                 // Enables SPIx interrupts
    IPC8bits.SPI2IP = 5;                 // SPIx interrupt priority

    SPI2STAT = 0;                        // SPIEN = 0    Disables module
                                                // not used 1
                                                // SPISIDL = 0  continues in Idle mode
                                                // not used 1
                                                // not used 1
                                                // SPIBEC 000   in Master Mode: Nb of transfer pendinf

                                                // SRMPT = 0    Shift register is not empty
                                                // SPIROV = 0   No Overflow
                                                // SRXMPT = 0   Rx Fifo not empty
    SPI2STATbits.SISEL = 2;           // SISEL = 010  Interrupt mode : receive buffer 3/4 full
                                                // SPITBF = 0   Transmit started, SPI2TXB is empty
                                                // SPIRBF = 0   Receive is not complete, SPI2RXB is empty

    SPI2CON1 = 0;                        // not used 3
                                                // DISSCK = 0   Internal clock enabled
                                                // DISSDO = 0   SDO pin controled by module
                                                // MODE16 = 0   Communication is Byte wide
    SPI2CON1bits.SMP = 0;             // SMP = 0      in Master Mode: Input data sample at middle of data
    SPI2CON1bits.CKE = 1;              // CKE = 1      Data changes on transition from active to idle

    SPI2CON1bits.SSEN = 0;           // SSEN = 0      Slave mode : not used here
    SPI2CON1bits.CKP = 0;             // CKP = 0        idle state is low level, active state is high level                                           
    SPI2CON1bits.MSTEN = 1;         // MSTEN = 1    Master mode
    SPI2CON1bits.SPRE = 4;            // SPRE = 100   Secondary Prescale 4/1
    SPI2CON1bits.PPRE = 2;            // PPRE = 10    Primary Prescale 4/1

    SPI2CON2 = 0;                        // FRMEN = 0    Framed SPI disabled
                                                // SPIFSD = 0   Frame sync pulse output
                                                // SPIFPOL = 0  Frame sync pulse is active-low
                                                // not used 5

                                                // not used 6
                                                // SPIFE = 0    frame sync pulse precedes first bit clock
    SPI2CON2bits.SPIBEN = 0;        // SPIBEN = 0   Enhanced buffer disabled 
                                               
    SPI2STATbits.SPIEN = 1;          // Enables SPI2
}
//-----------------------------------------------------------------------
unsigned char SPI2SendReceive(unsigned char Data)
{
unsigned char DataRead ;

    if (SPI2STATbits.SPITBF == 1)
        return 0xFF;
      else
        {   
           SPI2BUF = Data;
           DataRead = SPI2BUF;
           return DataRead;
        }
}
/************************************************************************
* Function:        SPI2 Interrupt
* PreCondition:   
* Input:      
* Output:     
* Overview:       
************************************************************************/
void __attribute__((__interrupt__, __shadow__)) _SPI2Interrupt(void)
{
    IFS2bits.SPI2IF = 0;        
}

Hello Mike

Thank you for your confirmations

My full duplex SPI connection between 2 PIC24FJ128GA010 works well now .... i had trouble in fact because my first board (with PIC24F) and my explorer16 (second PIC24F) were not on the same board .... and stupidly forgot to join ground signals. Shame on me !

Hello,
Sorry for the error in my previous post :: chips i am using are PIC24FJ128GA010...

I also checked in error data sheet and i also scratched my head a long time .... before i realized i had two seperate boards .... end no common ground!
In this case, it was kind of erratic !

Now i am happy