[参考译文] LP-MSP430FR2476：I2C 仅在关闭同一端口 LED 时工作

https://e2e.ti.com/support/microcontrollers/msp-low-power-microcontrollers-group/msp430/f/msp-low-power-microcontroller-forum/1085621/lp-msp430fr2476-i2c-only-functions-if-same-port-led-is-turned-off

您好，

我一直在使用启动板连接到 I2C 设备，使用 TI 提供的修改版 I2C 库。

我发现，如果引脚1.0上的 LED 同时亮起，则端口1的引脚2和3上的 I2C 模块将无法工作。 我在主部件的不同部分打开它后，能够验证这一点。 您可以在此处查看相关部分

while(reg!=2)
{
    i2c_master_read(0x41, 0xe0, &reg, 1);
}
reg = 1;
i2c_master_write(0x41, 0xe0, &reg, 1);

P1OUT = BIT0;

while(reg != 65)
{
    i2c_master_read(0x41, 0xe0, &reg, 1);
}

无论我在哪里说，该程序都会停止，因为 I2C 装置不再工作，并且保持在 LPM0中。

我是否缺少任何内容，或者 LED 和低功耗模式是否有某种关联？ 如果 LED 亮起，则 I2C 工作所需的中断不会触发。

为此，您可以看到我正在使用的 i2c 库：

I2C_Mode i2c_master_read(uint8_t devAdd, uint8_t regAdd, uint8_t* readBuf, uint8_t count)
{
    rxComplete = 0;
    /* Initialize state machine */
    masterMode = TX_REG_ADDRESS_MODE;
    transmitRegAddr = regAdd;
    rxByteCtr = count;
    txByteCtr = 0;
    receiveIndex = 0;
    transmitIndex = 0;
    receiveBuffer = readBuf;

    /* Initialize slave address and interrupts */
    UCB0I2CSA = devAdd;
    UCB0IFG &= ~(UCTXIFG + UCRXIFG);       // Clear any pending interrupts
    UCB0IE &= ~UCRXIE;                       // Disable RX interrupt
    UCB0IE |= UCTXIE;                        // Enable TX interrupt

    UCB0CTLW0 |= UCTR + UCTXSTT;             // I2C TX, start condition

    __bis_SR_register(LPM0_bits + GIE);              // Enter LPM0 w/ interrupts

    return 0;

}

I2C_Mode i2c_master_write(uint8_t devAdd, uint8_t regAdd, const uint8_t* regData, uint8_t count)
{
    txComplete = 0;
    /* Initialize state machine */
    masterMode = TX_REG_ADDRESS_MODE;
    transmitRegAddr = regAdd;

    //Copy register data to TransmitBuffer
    transmitBuffer = regData;

    txByteCtr = count;
    rxByteCtr = 0;
    receiveIndex = 0;
    transmitIndex = 0;

    /* Initialize slave address and interrupts */
    UCB0I2CSA = devAdd;
    UCB0IFG &= ~(UCTXIFG + UCRXIFG);       // Clear any pending interrupts
    UCB0IE &= ~UCRXIE;                       // Disable RX interrupt
    UCB0IE |= UCTXIE;                        // Enable TX interrupt

    UCB0CTLW0 |= UCTR + UCTXSTT;             // I2C TX, start condition
    __bis_SR_register(LPM0_bits + GIE);              // Enter LPM0 w/ interrupts

    return 0;
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCI_B0_VECTOR
__interrupt void USCI_B0_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_B0_VECTOR))) USCI_B0_ISR (void)
#else
#error Compiler not supported!
#endif
{
  //Must read from UCB0RXBUF
  uint8_t rx_val = 0;
  switch(__even_in_range(UCB0IV, USCI_I2C_UCBIT9IFG))
  {
    case USCI_NONE:          break;         // Vector 0: No interrupts
    case USCI_I2C_UCALIFG:   break;         // Vector 2: ALIFG
    case USCI_I2C_UCNACKIFG:                // Vector 4: NACKIFG
      break;
    case USCI_I2C_UCSTTIFG:  break;         // Vector 6: STTIFG
    case USCI_I2C_UCSTPIFG:  break;         // Vector 8: STPIFG
    case USCI_I2C_UCRXIFG3:  break;         // Vector 10: RXIFG3
    case USCI_I2C_UCTXIFG3:  break;         // Vector 12: TXIFG3
    case USCI_I2C_UCRXIFG2:  break;         // Vector 14: RXIFG2
    case USCI_I2C_UCTXIFG2:  break;         // Vector 16: TXIFG2
    case USCI_I2C_UCRXIFG1:  break;         // Vector 18: RXIFG1
    case USCI_I2C_UCTXIFG1:  break;         // Vector 20: TXIFG1
    case USCI_I2C_UCRXIFG0:                 // Vector 22: RXIFG0
        rx_val = UCB0RXBUF;
        if (rxByteCtr)
        {
          receiveBuffer[receiveIndex++] = rx_val;
          rxByteCtr--;
        }

        if (rxByteCtr == 1)
        {
          UCB0CTLW0 |= UCTXSTP;
        }
        else if (rxByteCtr == 0)
        {
          UCB0IE &= ~UCRXIE;
          masterMode = IDLE_MODE;
          __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
          P5OUT |= BIT1;
          P4OUT &= ~BIT7;
//          rxComplete = 1;
        }
        break;
    case USCI_I2C_UCTXIFG0:                 // Vector 24: TXIFG0
        switch (masterMode)
        {
          case TX_REG_ADDRESS_MODE:
              UCB0TXBUF = transmitRegAddr;
              if (rxByteCtr)
                  masterMode = SWITCH_TO_RX_MODE;   // Need to start receiving now
              else
                  masterMode = TX_DATA_MODE;        // Continue to transmission with the data in Transmit Buffer
              break;

          case SWITCH_TO_RX_MODE:
              UCB0IE |= UCRXIE;              // Enable RX interrupt
              UCB0IE &= ~UCTXIE;             // Disable TX interrupt
              UCB0CTLW0 &= ~UCTR;            // Switch to receiver
              masterMode = RX_DATA_MODE;    // State state is to receive data
              UCB0CTLW0 |= UCTXSTT;          // Send repeated start
              if (rxByteCtr == 1)
              {
                  //Must send stop since this is the N-1 byte
                  while((UCB0CTLW0 & UCTXSTT));
                  UCB0CTLW0 |= UCTXSTP;      // Send stop condition
              }
              break;

          case TX_DATA_MODE:
              if (txByteCtr)
              {
                  UCB0TXBUF = transmitBuffer[transmitIndex++];
                  txByteCtr--;
              }
              else
              {
                  //Done with transmission
                  UCB0CTLW0 |= UCTXSTP;     // Send stop condition
                  masterMode = IDLE_MODE;
                  UCB0IE &= ~UCTXIE;                       // disable TX interrupt
                  __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
//                  txComplete = 1;
              }
              break;

          default:
              __no_operation();
              break;
        }
        break;
    default: break;
  }
}