单片机在IAR仿真的时候能从SPI读到ADI芯片的数据。但是外部上电后SPI中 MISO 的信号一直都是高电平。
//                         MSP430F21x2
//                       -----------------
//                   /||              XIN|-
//             | |                 |
//    -------------   --|RST          XOUT|-
//   |           CS|<---|P3.0             |
//   | DATAIN<<<--------|P3.1SIMO    
            DATAOUT|--->|P3.2/UCB0SOMI    |
// ~>|AIN+  I/O CLK|<---|P3.3/CLK     |
//   |             |    |           
//
void SPI (void)  {    WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer
  BCSCTL3|=LFXT1S1;   // P1DIR |= 0x01;                            // P1.0 output
  P3SEL |= 0x0E;                            // P3.2,3 USCI_B0 option select
  P3DIR |= 0x01;                            // P3.0 output direction
  UCB0CTL0 |= UCCKPL + UCMSB + UCMST + UCSYNC;       // 3-pin, 8-bit SPI mstr, MSB 1st
  UCB0CTL1 |= UCSSEL_2;                                         // SMCLK
  UCB0BR0 = 0x02;
  UCB0BR1 = 0;
  UCB0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**
 }   [ 本帖最后由 glasshart 于 2012-6-18 14:41 编辑 ] 此帖出自小平头技术问答