SPI On F28377D

//###########################################################################
// FILE:   Example_28X7xSpi_FFDLB.c
// TITLE:  SPI Digital Loop Back program.
//
//! \addtogroup cpu01_example_list
//! <h1>SPI Digital Loop Back</h1>
//!
//!  This program uses the internal loop back test mode of the peripheral.
//!  Other then boot mode pin configuration, no other hardware configuration
//!  is required. Interrupts are not used.
//!
//!  A stream of data is sent and then compared to the received stream.
//!  The sent data looks like this: \n
//!  0000 0001 0002 0003 0004 0005 0006 0007 .... FFFE FFFF \n
//!  This pattern is repeated forever.
//!
//!  \b Watch \b Variables \n
//!  - \b sdata , sent data
//!  - \b rdata , received data
//		
//###########################################################################
// $TI Release: F2837xD Support Library v110 $
// $Release Date: Mon Apr  7 10:35:37 CDT 2014 $
//###########################################################################

#include "F28x_Project.h"     // Device Headerfile and Examples Include File

// Prototype statements for functions found within this file.
// __interrupt void ISRTimer2(void);
void delay_loop(void);
void spi_xmit(Uint16 a);
void spi_fifo_init(void);
void spi_init(void);
void error(void);

#define WORDLENGTH 0x7	// 8 bit chars

void main(void)
{
	int i = 0;
   Uint16 sdata;  // send data
   Uint16 rdata;  // received data
   
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the F2837xD_SysCtrl.c file.
   InitSysCtrl();

// Step 2. Initialize GPIO: 
// This example function is found in the F2837xD_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio();  // Skipped for this example  
// Setup only the GP I/O only for SPI-A functionality
// This function is found in F2837xD_Spi.c
   InitSpiaGpio();

// Step 3. Clear all __interrupts and initialize PIE vector table:
// Disable CPU __interrupts 
   DINT;

// Initialize PIE control registers to their default state.
// The default state is all PIE __interrupts disabled and flags
// are cleared.  
// This function is found in the F2837xD_PieCtrl.c file.
   InitPieCtrl();

// Disable CPU __interrupts and clear all CPU __interrupt flags:
   IER = 0x0000;
   IFR = 0x0000;
   
// Initialize the PIE vector table with pointers to the shell Interrupt 
// Service Routines (ISR).  
// This will populate the entire table, even if the __interrupt
// is not used in this example.  This is useful for debug purposes.
// The shell ISR routines are found in F2837xD_DefaultIsr.c.
// This function is found in F2837xD_PieVect.c.
   InitPieVectTable();
	
// Step 4. Initialize all the Device Peripherals:
// This function is found in F2837xD_InitPeripherals.c
// InitPeripherals(); // Not required for this example


   // comment out for non fifo (uncomment for fifo mode)
//   spi_fifo_init();	  // Initialize the Spi FIFO


   spi_init();		  // init SPI

// Step 5. User specific code:
// Interrupts are not used in this example. 
   sdata = 0x0000;							
   while(1)
   {
	   for(i=1;i<=0xF;i++)
	   {
		   // Transmit data
		   spi_xmit(i);
		   // Wait until data is received
//		   while(SpiaRegs.SPIFFRX.bit.RXFFST !=1) { }		// Uncomment for FIFO
		   while(SpiaRegs.SPISTS.bit.INT_FLAG != 1) {}		// COMMENT this line if using FIFO
		   // Check against sent data
		   rdata = SpiaRegs.SPIRXBUF;
		   if(rdata != i) ESTOP0;
		   asm("  nop");
	   }
   }
} 	

// Step 7. Insert all local Interrupt Service Routines (ISRs) and functions here:	

void delay_loop()
{
    long      i;
    for (i = 0; i < 1000000; i++) {}
}

void error(void)
{
   asm("     ESTOP0");						// Test failed!! Stop!
    for (;;);
}

void spi_init()
{    
	SpiaRegs.SPICCR.all =0x0000|WORDLENGTH;		// Reset on, rising edge, WORDLENGTH char bits
	SpiaRegs.SPICTL.all =0x0006;    		    // Enable master mode, normal phase,
                                                // enable talk, and SPI int disabled.
	SpiaRegs.SPIBRR =0x007F;									
//    SpiaRegs.SPICCR.all =0x0090|WORDLENGTH	// Relinquish SPI from Reset (LB mode)
    SpiaRegs.SPICCR.all =0x0080|WORDLENGTH;		// Relinquish SPI from Reset (external loopback mode)
    SpiaRegs.SPIPRI.bit.FREE = 1;               // Set so breakpoints don't disturb xmission
}

void spi_xmit(Uint16 a)
{
	Uint16 data;
	data = a<<8;		// left shift tx data 8 bits.
    SpiaRegs.SPITXBUF = data;
}    

void spi_fifo_init()										
{
// Initialize SPI FIFO registers
    SpiaRegs.SPIFFTX.all=0xE040;
    SpiaRegs.SPIFFRX.all=0x2044;
    SpiaRegs.SPIFFCT.all=0x0;
}  

//===========================================================================
// No more.
//===========================================================================