//******************************************************************************
//  MSP-FET430P140 Demo - DMA0/1/2, USART0 SPI 3-Wire SPI Slave P1.x Exchange
//
//  Description: SPI Master communicates at fast as possible, full-duplex with
//  SPI Slave using 3-wire mode. The level on P1.4/5 is TX'ed and RX'ed to P1.0
//  and P1.1. Master will pulse slave Reset on init to insure synch start.
//  With data transfer driven directly by DMA - no CPU resources used.
//  DMA0 trigger from TX read, which uses MPY to shift read P1 left
//  DMA1 trigger from MPY moves shifted P1 data to the USART0 TX buffer
//  DMA2 trigger from USART0 RX buffer moves received data to P1
//  Slave normal mode is LPM4.
//  ACLK = n/a, MCLK = SMCLK = DCO ~ 800kHz, ULCK = external
//  //* Final Production MSP430F16x(x) Device Required *//
//
//             fet140_dma_15              fet140_dma_14
//             MSP430F169 Slave           MSP430F169 Master
//             -----------------          -----------------
//            |              XIN|-    /|\|              XIN|-
//            |                 |      | |                 |
//            |             XOUT|-     --|RST          XOUT|-
//            |                 | /|\    |                 |
//            |              RST|--+<----|P3.0             |
//      LED <-|P1.0             |        |             P1.4|<-
//      LED <-|P1.1             |        |             P1.5|<-
//          ->|P1.4             |        |             P1.0|-> LED
//          ->|P1.5             |        |             P1.1|-> LED
//            |       SIMO0/P3.1|<-------|P3.1/SIMO0       |
//            |       SOMI0/P3.2|------->|P3.2/SOMI0       |
//            |        UCLK/P3.3|<-------|P3.3/UCLK        |
//
//  M. Buccini / A. Dannenberg
//  Texas Instruments Inc.
//  November 2005
//  Built with IAR Embedded Workbench Version: 3.30A
//******************************************************************************

#include  <msp430x16x.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog
  P1OUT = 0x00;                             // P1.0 setup for LED output
  P1DIR |= 0x03;
  P3SEL |= 0x0E;                            // P3.1,2,3 SPI option select
  U0CTL = CHAR + SYNC + SWRST;              // 8-bit, SPI
  U0TCTL = CKPL + STC;                      // Polarity, 3-wire
  U0BR0 = 0x02;                             // SPICLK = SMCLK/2
  U0BR1 = 0x00;
  U0MCTL = 0x00;
  ME1 |= USPIE0;                            // Module enable
  U0CTL &= ~SWRST;                          // SPI enable

  MPY = 0x1000;                             // MPY first operand

// Setup triggers first
  DMACTL0 = DMA2TSEL_3 + DMA1TSEL_11 + DMA0TSEL_4;  // URXIFG0, MPY, UTXIFG0

// TX load
  DMA1SA = RESHI_;                          // Src address = multiplier
  DMA1DA = U0TXBUF_;                        // Dst address = RAM memory
  DMA1SZ = 1;                               // Size in bytes
  DMA1CTL = DMADT_4 + DMASBDB + DMAEN;      // Sng, config

// TX Init
  DMA0SA = P1IN_;                           // Src address
  DMA0DA = OP2_;                            // Dst address = multiplier
  DMA0SZ = 1;                               // Size in words
  DMA0CTL = DMADT_4 + DMASBDB + DMALEVEL + DMAEN;  // Sng rpt, config

// RX Store
  DMA2SA = U0RXBUF_;                        // Src address = UART RX Buffer
  DMA2DA = P1OUT_;                          // Dst address = P1
  DMA2SZ = 1;                               // Size in bytes
  DMA2CTL = DMADT_4 + DMASBDB + DMAEN;      // Sng, config

  _BIS_SR(LPM4_bits + GIE);                 // Enter LPM4 w/ interrupt
}