fet140_spi0_04.c

天祥电子-10天学会MSP430单片机开发板资源TI提供的例程

//******************************************************************************
//  MSP-FET430P140 Demo - USART0, SPI Interface to TLV5616 DAC
//
//  Description: Demonstrate USART0 in SPI mode interface to TLV5616 DAC.
//  USART0 is used to transmit data to DAC, software generated frame sync
//  pulse, DAC is updated inside CCR0 ISR operating in continuos mode.
//  ACLK= n/a, MCLK= SMCLK= UCLK= default DCOCLK
//  //* SWRST** please see MSP430x1xx Users Guide for description *//
//
//               MSP430F149
//            -----------------
//        /|\|              XIN|-
//         | |                 |           TLV5616
//         --|RST          XOUT|-       -------------
//           |             P3.0|------>|FS        OUT|--> ~ 390Hz
//           |       SIMO0/P3.1|------>|DIN          |
//           |       UCLK0/P3.3|------>|SCLK       CS|-|
//           |                 |       |             | v
//
//
//  M. Buccini
//  Texas Instruments Inc.
//  Feb 2005
//  Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************

#include  <msp430x14x.h>

unsigned int pointer;                       // 16-bit value to write

//------------------------------------------------------------------------------
// 12-bit Sine Lookup table with 32 steps
//------------------------------------------------------------------------------
static unsigned int Sin_tab[32] = {
        2048,
        2447,
        2831,
        3185,
        3495,
        3750,
        3939,
        4056,
        4095,
        4056,
        3939,
        3750,
        3495,
        3185,
        2831,
        2447,
        2048,
        1648,
        1264,
        910,
        600,
        345,
        156,
        39,
        0,
        39,
        156,
        345,
        600,
        910,
        1264,
        1648
};

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  P3SEL |= 0xA;                             // P3.1,3 SPI option select
  P3DIR |= 0xB;                             // P3.0,1,3 output direction
  P3OUT &= ~0x1;                            // FS reset
  ME1 |= USPIE0;                            // Enable USART0 SPI
  UCTL0 |= CHAR + SYNC + MM;                // 8-bit SPI Master **SWRST**
  UTCTL0 = CKPH + CKPL + SSEL1 + STC;       // Inv. delayed, SMCLK, 3-pin
  UBR00 = 0x2;                              // ACLK/2 for baud rate
  UBR10 = 0x0;                              // ACLK/2 for baud rate
  UMCTL0 = 0x0;                             // Clear modulation
  UCTL0 &= ~SWRST;                          // Initialize USART state machine
  pointer = 0;                              // Clear pointer
  CCTL0 = CCIE;                             // CCR0 interrupt enabled
  CCR0 = 64-1;                              // ~ 390Hz Clock period
  TACTL = TASSEL_2 + MC_1;                  // SMCLK, Up-mode

  _BIS_SR(LPM0_bits + GIE);            	    // Enter LPM0 w/ interrupt
}

// Timer A0 interrupt service routine
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A(void)
{
  P3OUT |= 0x1;                             // FS set
  P3OUT &= ~0x1;                            // FS reset
  TXBUF0 = Sin_tab[pointer] >> 8;
  TXBUF0 = Sin_tab[pointer];
  pointer++;
  pointer &= 0x1F;
}