fet430_dma_05.c

msp430开发c语言例程

//******************************************************************************
//  MSP-FET430P430 Demo - DMA0 Repeated Block to DAC1 8-bit Sine Output, TBCCR2, DCO 
//
//  Description; DMA0 is used to transfer a sine look-up table byte-by-byte 
//  as a repeating block to DAC12_1. The effect is sine wave output. Timer_B 
//  operates in upmode with CCR2 loading DAC12_1 on rising edge, CCR2_CCIFG
//  triggering next DMA0 transfer. Use external reference on VeRef+.
//
//               MSP430FG439          
//            -----------------
//        /|\|              XIN|-  
//         | |                 |    
//         --|RST          XOUT|-       
//           |                 |
//  Ext Ref->|VeRef+  DAC1/P6.7|--> ~ 1kHz sine wave output
//
//
//  M.Buccini
//  Texas Instruments, Inc
//  June 2004
//  Built with IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include  <msp430xG43x.h>

//------------------------------------------------------------------------------ 
// Flash - 8-bit Sine Lookup table with 32 steps
//------------------------------------------------------------------------------ 
const char Sin_tab[32] = { 128, 152, 176, 198, 218, 234, 245, 253, 255, 253,
245, 234, 218, 198, 176, 152, 128, 103, 79, 57, 37, 21, 10, 2, 0, 2, 10, 21,
37, 57, 79, 103 };

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;             // Stop watchdog
  DMA0SA = (int) Sin_tab;               // Source block address
  DMA0DA = DAC12_1DAT_;                 // Destination single address
  DMA0SZ = 0x20;                        // Block size
  DMACTL0 = DMA0TSEL_2;                 // Timer_B.CCIFG2 trigger
  DMA0CTL = DMASBDB + DMADT_4 + DMASRCINCR_3 + DMAEN;  // config
  DAC12_1CTL = DAC12SREF_2+ DAC12RES + DAC12LSEL_3 + DAC12IR + DAC12AMP_5 + DAC12ENC;
  
  TBCCTL2 = OUTMOD_7;                   // Reset/set
  TBCCR2 = 1;                           // PWM Duty Cycle	  
  TBCCR0 = 32-1;                        // ~1kHz Clock period 
  TBCTL = TBSSEL_2 + MC_1;              // SMCLK, up mode

  _BIS_SR(LPM0_bits);                   // Enter LPM0
}