现在，用两块430单片机进行ＳＰＩ的通信，希望是从机发送数据，主机接收数据并返回。编写程序后发现主机没有主动产生时钟，现在用的是３线的ＳＰＩ，是否需要４线的才能实现？
//******************************************************************************
//作为主机，接收SPI数据，并转换后发送回去，然后上传串口
#include <msp430.h>
unsigned char MST_Data,SLV_Data;
void Serial_init()
{
P10SEL = 0x30; // P3.4,5 = USCI_A0 TXD/RXD
UCA3CTL1 |= UCSWRST; // **Put state machine in reset**
UCA3CTL1 |= UCSSEL_2; // SMCLK
UCA3BR0 = 6; // 1MHz 9600 (see User's Guide)
UCA3BR1 = 0; // 1MHz 9600
UCA3MCTL = UCBRS_0 + UCBRF_13 + UCOS16; // Modln UCBRSx=0, UCBRFx=0,
// over sampling
UCA3CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
//UCA3IE |= UCRXIE; // Enable USCI_A0 RX interrupt
}
int main(void)
{
WDTCTL = WDTPW+WDTHOLD; // Stop watchdog timer
Serial_init();
//P1OUT |= 0x02; // Set P1.0 for LED
// Set P1.1 for slave reset
// P1DIR |= 0x03; // Set P1.0-2 to output direction
P9SEL |= 0x0E; // P3.5,4,0 option select
UCB2CTL1 |= UCSWRST; // **Put state machine in reset**
UCB2CTL0 |= UCMST+UCSYNC+UCCKPL+UCMSB; // 3-pin, 8-bit SPI master
// Clock polarity high, MSB
UCB2CTL1 |= UCSSEL_2; // SMCLK
UCB2BR0 = 0x02; // /2
UCB2BR1 = 0; //
// UCA0MCTL = 0; // No modulation
UCB2CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
UCB2IE |= UCRXIE; // Enable USCI_A0 RX interrupt
//P1OUT &= ~0x02; // Now with SPI signals initialized,
// P1OUT |= 0x02; // reset slave
__delay_cycles(100); // Wait for slave to initialize
__bis_SR_register(GIE); // Enter LPM4, enable interrupts
while(1);
}
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_B2_VECTOR
__interrupt void USCI_B2_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_B2_VECTOR))) USCI_B2_ISR (void)
#else
#error Compiler not supported!
#endif
{
switch(__even_in_range(UCB2IV,4))
{
case 0:break; // Vector 0 - no interrupt
case 2: // Vector 2 - RXIFG
while (!(UCA3IFG&UCTXIFG)); // USCI_A0 TX buffer ready?
UCA3TXBUF = 0xff-UCB2RXBUF; // TX -> RXed character
while (!(UCB2IFG&UCTXIFG)); // USCI_A0 TX buffer ready?
UCB2TXBUF = 0xff-UCB2RXBUF; // TX -> RXed character
break;
case 4:break; // Vector 4 - TXIFG
default: break;
}
}
