大家好！我现在尝试用两块MSP430G2553 LaunchPad进行SPI通信，示例代码用的TI的官方代码：
Master：
#include "msp430g2553.h"
unsigned char MST_Data, SLV_Data;
void main(void)
{
volatile unsigned int i;
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
P1OUT = 0x00; // P1 setup for LED & reset output
P1DIR |= BIT0 + BIT5; //
P1SEL = BIT1 + BIT2 + BIT4;
P1SEL2 = BIT1 + BIT2 + BIT4;
UCA0CTL0 |= UCCKPL + UCMSB + UCMST + UCSYNC; // 3-pin, 8-bit SPI master
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 |= 0x02; // /2
UCA0BR1 = 0; //
UCA0MCTL = 0; // No modulation
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI0 RX interrupt
P1OUT &= ~BIT5; // Now with SPI signals initialized,
P1OUT |= BIT5; // reset slave
__delay_cycles(75); // Wait for slave to initialize
MST_Data = 0x01; // Initialize data values
SLV_Data = 0x00;
UCA0TXBUF = MST_Data; // Transmit first character
__bis_SR_register(LPM0_bits + GIE); // CPU off, enable interrupts
}
// Test for valid RX and TX character
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR(void)
{
volatile unsigned int i;
while (!(IFG2 & UCA0TXIFG)); // USCI_A0 TX buffer ready?
if (UCA0RXBUF == SLV_Data) // Test for correct character RX'd
P1OUT |= BIT0; // If correct, light LED
else
P1OUT &= ~BIT0; // If incorrect, clear LED
MST_Data++; // Increment master value
SLV_Data++; // Increment expected slave value
UCA0TXBUF = MST_Data; // Send next value
__delay_cycles(50); // Add time between transmissions to
} // make sure slave can keep up
Slaver:
#include "msp430g2553.h"
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
while (!(P1IN & BIT4)); // If clock sig from mstr stays low, // it is not yet in SPI mode
P1SEL = BIT1 + BIT2 + BIT4;
P1SEL2 = BIT1 + BIT2 + BIT4;
UCA0CTL1 = UCSWRST; // **Put state machine in reset**
UCA0CTL0 |= UCCKPL + UCMSB + UCSYNC; // 3-pin, 8-bit SPI master
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI0 RX interrupt
__bis_SR_register(LPM4_bits + GIE); // Enter LPM4, enable interrupts
}
// Echo character
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR (void)
{
while (!(IFG2 & UCA0TXIFG)); // USCI_A0 TX buffer ready?
UCA0TXBUF = UCA0RXBUF;
}
现在我碰到下面的问题：
（1）在master的SDO端口，可以看到发出的数据，但是只有7个时钟信号，而不是8个时钟信号。另外，数据发送完成后，数据线上没有STOP信号，而是保持高电平或低电平？
（2）在发送的两个相邻数据，可以看到数据为递增的，但是从Master代码可以看到，只有在进入到接收中断后。数据才进行累加，而我在SDI端口并没有看到数据。那是什么触发中断而对MST_Data++的。
（3）在Master的SDI端口没有数据输入，即slaver没有数据回报，只有杂波。我想问问上面的Master和Slaver代码这样配合能通信成功吗？如果不行，哪里需要注意或修改？
大家帮忙看看，谢谢了！
