芯片用的是msp430g2533，温度传感器用的tmp101，现在用官方例程，iic两路信号没有波形，把低功耗注释掉，波形正常，但是UCB0RXBUF寄存器的数据始终是0x80，求解答，谢谢，程序如下

这个是官方例程吗？

个人觉得逻辑上有错误，标注在你的代码中。

不妨在你中断函数设置断点，看看程序运行是否如我的推测。谢谢！

yao wang5 说：

#include <msp430.h>

unsigned int RxByteCtr;
unsigned int RxWord;

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= BIT0; // P1.0 output
P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = 0x4e; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0RXIE; // Enable RX interrupt
TACTL = TASSEL_2 + MC_2; // SMCLK, contmode

while (1)
{
RxByteCtr = 2; // Load RX byte counter  //每次运行到这里，这个变量都强行赋值为2 
UCB0CTL1 |= UCTXSTT; // I2C start condition
__bis_SR_register(CPUOFF + GIE); // Enter LPM0, enable interrupts

// 如果I2C接收到数据中断，其值应该只获取到1byte  程序继续往下运行。 你可以发现你获取的值应该就是一个BYTE  后又回到RxByteCtr = 2;这个代码

// Remain in LPM0 until all data
// is RX'd

if (RxWord < 0x1d00) // >28C?
P1OUT &= ~0x01; // No, P1.0 = 0
else
P1OUT |= 0x01; // Yes, P1.0 = 1

__disable_interrupt();  // 这个可以屏蔽 
TACCTL0 |= CCIE; // TACCR0 interrupt enabled  //这个定时还有其它配置没有
__bis_SR_register(CPUOFF + GIE); // Enter LPM0, enable interrupts
// Remain in LPM0 until TACCR0
// interrupt occurs
TACCTL0 &= ~CCIE; // TACCR0 interrupt disabled
}
}

#pragma vector = TIMER0_A0_VECTOR
__interrupt void TA0_ISR(void)
{
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}

// The USCIAB0TX_ISR is structured such that it can be used to receive any
// 2+ number of bytes by pre-loading RxByteCtr with the byte count.
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
RxByteCtr--; // Decrement RX byte counter

if (RxByteCtr)
{
RxWord = (unsigned int)UCB0RXBUF << 8; // Get received byte
if (RxByteCtr == 1) // Only one byte left?
UCB0CTL1 |= UCTXSTP; // Generate I2C stop condition
}
else
{
RxWord |= UCB0RXBUF; // Get final received byte,
// Combine MSB and LSB
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
}

现在按你说的操作，早中断函数设置断点，波形和寄存器都是对的，请问，程序该怎么改呢？谢谢

刚才设了断点运行正常，同样的程序，现在设置断点，程序不停止，也没有波形输出，是什么原因？ccs编译器的问题么？

改成这样测试一下，看看结果是否正确。Timer 配置不完整，你可以在这里换成一个比较长的延时看看，这个是等待I2C数据接收完成。

yao wang5 说：

#include <msp430.h>

unsigned int RxByteCtr;
unsigned int RxWord;

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= BIT0; // P1.0 output
P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = 0x4e; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation

RxByteCtr = 2; // Load RX byte counter

IE2 |= UCB0RXIE; // Enable RX interrupt
TACTL = TASSEL_2 + MC_2; // SMCLK, contmode

while (1)
{
//RxByteCtr = 2; // Load RX byte counter
UCB0CTL1 |= UCTXSTT; // I2C start condition
//__bis_SR_register(CPUOFF + GIE); // Enter LPM0, enable interrupts
// Remain in LPM0 until all data
// is RX'd

if (RxWord < 0x1d00) // >28C?
P1OUT &= ~0x01; // No, P1.0 = 0
else
P1OUT |= 0x01; // Yes, P1.0 = 1

//__disable_interrupt();
TACCTL0 |= CCIE; // TACCR0 interrupt enabled
__bis_SR_register(CPUOFF + GIE); // Enter LPM0, enable interrupts
// Remain in LPM0 until TACCR0
// interrupt occurs
TACCTL0 &= ~CCIE; // TACCR0 interrupt disabled
}
}

#pragma vector = TIMER0_A0_VECTOR
__interrupt void TA0_ISR(void)
{
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}

// The USCIAB0TX_ISR is structured such that it can be used to receive any
// 2+ number of bytes by pre-loading RxByteCtr with the byte count.
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
RxByteCtr--; // Decrement RX byte counter

if (RxByteCtr)
{
RxWord = (unsigned int)UCB0RXBUF << 8; // Get received byte
if (RxByteCtr == 1) // Only one byte left?
UCB0CTL1 |= UCTXSTP; // Generate I2C stop condition
}
else
{
RxWord |= UCB0RXBUF; // Get final received byte,
// Combine MSB and LSB
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0

RxByteCtr = 2; // Load RX byte counter
}
}

这个出了波形，凡是波形不正确，寄存器里的值还是0x80。用刚才测试的程序，没有波形了并且scl被拉低了，是这颗芯片msp430g2533的iic存在问题么？时好时坏？有没有这颗芯片不用中断的iic的例程呢？

在MSPWARE中有很多I2C例程，建议你还是跑一下例程先。如上图所示，CCS环境中。

你贴的好像是TI给官方例程，我刚刚检查一下逻辑，是没有问题的。如果波形出不来是因为进入低功耗的原因吗？

那我建议如下更改：

#include <msp430.h>

unsigned int RxByteCtr;
unsigned int RxWord;

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= BIT0; // P1.0 output
P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = 0x4e; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0RXIE; // Enable RX interrupt
TACTL = TASSEL_2 + MC_2; // SMCLK, contmode

while (1)
{
RxByteCtr = 2; // Load RX byte counter
UCB0CTL1 |= UCTXSTT; // I2C start condition
//__bis_SR_register(CPUOFF + GIE); // Enter LPM0, enable interrupts//不进入低功耗状态
// Remain in LPM0 until all data
// is RX'd

while(RxByteCtr); //等待数据接收完毕 两个字节 

if (RxWord < 0x1d00) // >28C?
P1OUT &= ~0x01; // No, P1.0 = 0
else
P1OUT |= 0x01; // Yes, P1.0 = 1

__disable_interrupt();
TACCTL0 |= CCIE; // TACCR0 interrupt enabled
__bis_SR_register(CPUOFF + GIE); // Enter LPM0, enable interrupts
// Remain in LPM0 until TACCR0
// interrupt occurs
TACCTL0 &= ~CCIE; // TACCR0 interrupt disabled
}
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = TIMER0_A0_VECTOR
__interrupt void TA0_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(TIMER0_A0_VECTOR))) TA0_ISR (void)
#else
#error Compiler not supported!
#endif
{
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}

// The USCIAB0TX_ISR is structured such that it can be used to receive any
// 2+ number of bytes by pre-loading RxByteCtr with the byte count.
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB0TX_VECTOR))) USCIAB0TX_ISR (void)
#else
#error Compiler not supported!
#endif
{
RxByteCtr--; // Decrement RX byte counter

if (RxByteCtr)
{
RxWord = (unsigned int)UCB0RXBUF << 8; // Get received byte
if (RxByteCtr == 1) // Only one byte left?
UCB0CTL1 |= UCTXSTP; // Generate I2C stop condition
}
else
{
RxWord |= UCB0RXBUF; // Get final received byte,
// Combine MSB and LSB
//__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
}

都还是老样子，没有波形，寄存器里的数值也不变，是不是芯片的iic硬件有问题？能不能提供一下用IO口模拟iic读取tmp101温度的例程，来测试下p1.6和p1.7是不是正常，谢谢

在中断函数中设置断点试试？程序运行停在什么地方？可以把后面定时器进入LPM0也屏蔽看看。

设置了断点程序不停，每次手动暂停程序都停在这里while(RxByteCtr); //等待数据接收完毕 两个字节

还是没有波形

那说明没有进入中断服务函数中，这个你需要检查一下你的外围电路是否存在异常。

把SCL SDA两者波形同时抓出来，第一看看主设备有没有指令发出，第二在确认从设备是否效应。

偶尔是对的，外围电路检查过没问题。

电路图如附件