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

 //Description:SPI slave talks to SPI master using 3-wire mode. Data is sent

 //to the master starting at 0x00 and increments. Received data from the

 //master is expected to start at 0xff and decrements with each transmission.

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

 #include <msp430x14x.h>

 char MST_data = 0x00,SLV_data = 0XFF;

 void main()

 {

   WDTCTL = WDTPW + WDTHOLD;

   P6DIR |= BIT0;

   P6OUT |= BIT0;

   P3SEL = 0X0E;                        //P3.1,2,3 SPI option select

   P3DIR |= BIT1;

   P3OUT |= BIT1;

   U0CTL |= SWRST + SYNC + MM +CHAR;   //master spi 8-bit

   U0TCTL |= CKPH + SSEL1 + STC;

   U0TCTL &= ~CKPL;

   U0BR0 = 0X02;                      //SPICLK = SMCLK/2

   U0BR1 = 0X00;

   U0MCTL = 0X00;

   ME1 = USPIE0;

   U0CTL &= ~SWRST;

   IE1 |= URXIE0;     //receive enable

   _EINT();

   while()

   {

     TXBUF0 = MST_data;

     LPM0;

   }

 }

 #pragma vector=USART0RX_VECTOR

 __interrupt void SPI_RX()

 {

   P6OUT ^= BIT0;

   while((IFG1 & UTXIFG0)==);

   if(U0RXBUF == SLV_data)

   {

     SLV_data = SLV_data - ;

     MST_data = MST_data + ;

     U0TXBUF  = MST_data;

   }

   else

     TXBUF0 = MST_data;

 }

 #include <msp430x14x.h>

 char MST_data = 0x00,SLV_data = 0xff;

 void main()

 {

   WDTCTL = WDTPW + WDTHOLD;

   P3SEL = 0X0E;

   UOCTL = CHAR + SYNC + SWRST;

   U0TCTL = CKPL + SSEL1 + STC;

   U0CLT &= ~CKPH;

   ME1 |= USPIE0;

   U0CTL &= ~SWRST;

   IE1 |= URXIE0;

   _EINT();

   while()

   {

     TXBUF0 = SLV_data;

     LMP4;

   }

 }

 #pragma vector=USART0RX_VECTOR

 __interrupt void USART0_RX()

 {

   while((IFG1 & OFIFG)==);

   if(U0RXBUF == MST_data)

   {

     SLV_data = SLV_data - ;

     MST_data = MST_data + ;

     TXBUF0 = SLV_data;

   }

   else

     TXBUF0 = SLV_data;

 }