fg4619_s_spi.c

MSP430FG4619的SPI子程序

//******************************************************************************
//   MSP430xG46x Demo - USART1, SPI 3-Wire Slave Data Echo
//
//   Description: SPI slave talks to SPI master using 3-wire mode. Data received
//   from master is echoed back.  USART1 RX ISR is used to handle communication,
//   CPU normally in LPM4.  Prior to initial data exchange, master pulses
//   slaves RST for complete reset.
//   ACLK = 32.768kHz, MCLK = SMCLK = DCO = ~1048kHz
//
//   Use with SPI Master Incremented Data code example.  If the slave is in
//   debug mode, the reset signal from the master will conflict with slave's
//   JTAG; to work around, use IAR's "Release JTAG on Go" on slave device.  If
//   breakpoints are set in slave RX ISR, master must stopped also to avoid
//   overrunning slave RXBUF.
//
//                    MSP430xG461x                       MSP430xG461x
//                 -----------------                  -----------------
//             /|\|              XIN|                 |                 | /|\      
//              | |                 |                 |                 |  |
//              --|RST          XOUT|                 |              RST|------Master
//                |                 |                 |                 |
//                |             P4.3|SIMO1<----->SOMI1|P4.3             |
//                |                 |                 |                 |
//          LED <-|P5.1         P4.4|SOMI1<----->SIMO1|P4.4         XIN |-
//                |                 |                 |                 |  32KHZ
//  Slave reset <-|P5.2         P4.5|UCLK1<----->UCLK1|P4.5         XOUT|-
//
//
//   K. Quiring/ M. Mitchell
//   Texas Instruments Inc.
//   March 2006
//   Built with IAR Embedded Workbench Version: 3.41A
//******************************************************************************
#include  <msp430xG46x.h>

void main(void)
{
  volatile unsigned int i;
  WDTCTL = WDTPW+WDTHOLD;                   // 关看门狗
  FLL_CTL0 |= XCAP14PF;                     // 设置电容
  do
  {
  IFG1 &= ~OFIFG;                           // 清晶振失效标志
  for (i = 0x47FF; i > 0; i--);             //  
  }
  while ((IFG1 & OFIFG));                   //  
  for(i=2100;i>0;i--);                      //                                
  while(!(P4IN&0x20));                      // 
  P4SEL |= 0x038;                           // P4.5,4,3 选择 SPI 功能  
  U1CTL = CHAR+SYNC+SWRST;                  // 8-bit, SPI, 从机
  U1TCTL |= CKPL+STC;                       // 极性, UCLK, 3线制
  ME2 |= USPIE1;                            // 模块使能
  U1CTL &= ~SWRST;                          // SPI 使能
  IE2 |= URXIE1;                            // 接收中断使能

  _BIS_SR(LPM4_bits + GIE);                 // 开中断，进入低功耗 LPM4 
}

#pragma vector=USART1RX_VECTOR
__interrupt void USART1RX_ISR (void)
{
  while (!(IFG2 & UTXIFG1));                // USART1 发送准备？
  U1TXBUF = U1RXBUF;
}