//******************************************************************************
//  MSP-FET430P140 Demo - USART1, Ultra-Low Pwr UART 9600 Echo ISR, 32kHz ACLK
//
//  Description: Echo a received character, RX ISR used. Normal mode is LPM3,
//  USART1 RX interrupt triggers TX Echo.
//  ACLK = UCLK1 = LFXT1 = 32768, MCLK = SMCLK = DCO~ 800k
//  Baud rate divider with 32768hz XTAL @9600 = 32768Hz/9600 = 3.41 (0003h 4Ah )
//  //* An external watch crystal is required on XIN XOUT for ACLK *//	
//
//
//                MSP430F149
//            -----------------
//        /|\|              XIN|-
//         | |                 | 32kHz
//         --|RST          XOUT|-
//           |                 |
//           |             P3.6|----------->
//           |                 | 9600 - 8N1
//           |             P3.7|<-----------
//
//
//  M. Buccini
//  Texas Instruments Inc.
//  Feb 2005
//  Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************

#include  <msp430x14x.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;      // Stop WDT
  P3SEL |= 0xC0;                 // P3.6,7 = USART1 TXD/RXD
  ME2 |= UTXE1 + URXE1;          // Enable USART1 TXD/RXD   IFG2:URXIFG1接受中斷標志位  UTXIFG1發送中斷標志位 IFG1
  UCTL1 |= CHAR;                 // 8-bit character         IE2: URXIE1接受中斷使能     UTXIE1發送中斷使能    IE1  
  UTCTL1 |= SSEL0;               // UCLK = ACLK             ME2: URXE1接受允許          UTXE1發送允許         ME1
  UBR01 = 0x03;                  // 32k/9600 - 3.41
  UBR11 = 0x00;                             //
  UMCTL1 = 0x4A;                            // Modulation
  UCTL1 &= ~SWRST;                          // Initialize USART state machine
  IE2 |= URXIE1;                            // Enable USART1 RX interrupt

  _BIS_SR(LPM3_bits + GIE);                 // Enter LPM3 w/ interrupt
}

#pragma vector=UART1RX_VECTOR
__interrupt void usart1_rx (void)
{
  while (!(IFG2 & UTXIFG1));                // USART1 TX buffer ready?
  TXBUF1 = RXBUF1;                          // RXBUF1 to TXBUF1
}