MSP430FR2676: I2C Remapping issue

To use UCB1 with P4.3/4, you need to set SYSCFG3:USCIB1RMP=1 [Ref data sheet (SLASEO5C) Table 6-11 and User Guide (SLAU445I) Table 1-32]. Just add:

> SYSCFG3 |= USCIB1RMP; // Use P4 pins per data sheet Table 6-11

Hello All,

Thnak You for your suggestion and help

However, I had already made the respective changes and also verified it again as per your suggestions which is mentioned in i2c.c file which is attached in the last post,

But stil i am not able to solve the issue, I have also attached the code below,

void I2CInit(void)
{
    SYSCFG3|=USCIB1RMP;                       //Set the remapping source   

   // I2C pins
    P4SEL0 |= BIT4 | BIT3;
    P4SEL1 &= ~(BIT4 | BIT3);


    //Initialize Clock if required
    UCB1CTLW0 = UCSWRST;                      // Enable SW reset
    UCB1CTLW0 |= UCMODE_3 | UCMST | UCSSEL__SMCLK | UCSYNC; // I2C master mode, SMCLK
    UCB1BRW = 100;                            // fSCL = SMCLK/160 = ~100kHz
    UCB1I2CSA = SLAVE_ADDR;                   // Slave Address
    UCB1CTLW0 &= ~UCSWRST;                    // Clear SW reset, resume operation
    UCB1IE |= UCNACKIE;
}

I2C_Mode I2C_Master_ReadReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t count)
{
    /* Initialize state machine */
    MasterMode = TX_REG_ADDRESS_MODE;
    ui8TransmitRegAddr = reg_addr;
    ui8RXByteCounter = count;
    ui8TXByteCounter = 0;
    ui8ReceiveIndex = 0;
    ui8TransmitIndex = 0;

    /* Initialize slave address and interrupts */
    UCB1I2CSA = dev_addr;
    UCB1IFG &= ~(UCTXIFG + UCRXIFG);       // Clear any pending interrupts
    UCB1IE &= ~UCRXIE;                       // Disable RX interrupt
    UCB1IE |= UCTXIE;                        // Enable TX interrupt

    UCB1CTLW0 |= UCTR + UCTXSTT;             // I2C TX, start condition
    __bis_SR_register(LPM0_bits + GIE);              // Enter LPM0 w/ interrupts

    return MasterMode;

}

I2C_Mode I2C_Master_WriteReg(uint8_t dev_addr, uint8_t reg_addr, uint8_t *reg_data, uint8_t count)
{
    /* Initialize state machine */
    MasterMode = TX_REG_ADDRESS_MODE;
    ui8TransmitRegAddr = reg_addr;

    ui8TXByteCounter = count;
    ui8RXByteCounter = 0;
    ui8ReceiveIndex = 0;
    ui8TransmitIndex = 0;

    /* Initialize slave address and interrupts */
    UCB1I2CSA = dev_addr;
    UCB1IFG &= ~(UCTXIFG + UCRXIFG);       // Clear any pending interrupts
    UCB1IE &= ~UCRXIE;                       // Disable RX interrupt
    UCB1IE |= UCTXIE;                        // Enable TX interrupt

    UCB1CTLW0 |= UCTR + UCTXSTT;             // I2C TX, start condition
    __bis_SR_register(LPM0_bits + GIE);              // Enter LPM0 w/ interrupts

    return MasterMode;
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = USCI_B1_VECTOR
__interrupt void USCI_B1_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_B1_VECTOR))) USCI_B1_ISR (void)
#else
#error Compiler not supported!
#endif
{
  //Must read from UCB0RXBUF
  uint8_t rx_val = 0;
  switch(__even_in_range(UCB1IV, 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 = UCB1RXBUF;
        if (ui8RXByteCounter)
        {
          ui8ReceiveBuffer[ui8ReceiveIndex++] = rx_val;
          ui8Dummy[ui8dmyi++] = rx_val;
          ui8RXByteCounter--;
        }

        if (ui8RXByteCounter == 1)
        {
          UCB1CTLW0 |= UCTXSTP;
        }
        else if (ui8RXByteCounter == 0)
        {
          UCB1IE &= ~UCRXIE;
          MasterMode = IDLE_MODE;
          __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
        }
        break;
    case USCI_I2C_UCTXIFG0:                 // Vector 24: TXIFG0
        switch (MasterMode)
        {
          case TX_REG_ADDRESS_MODE:
              UCB1TXBUF = ui8TransmitRegAddr;
              if (ui8RXByteCounter)
                  MasterMode = SWITCH_TO_RX_MODE;   // Need to start receiving now
              else
                  MasterMode = TX_DATA_MODE;        // Continue to transmision with the data in Transmit Buffer
              break;

          case SWITCH_TO_RX_MODE:
              UCB1IE |= UCRXIE;              // Enable RX interrupt
              UCB1IE &= ~UCTXIE;             // Disable TX interrupt
              UCB1CTLW0 &= ~UCTR;            // Switch to receiver
              MasterMode = RX_DATA_MODE;    // State state is to receive data
              UCB1CTLW0 |= UCTXSTT;          // Send repeated start
              if (ui8RXByteCounter == 1)
              {
                  //Must send stop since this is the N-1 byte
                  while((UCB1CTLW0 & UCTXSTT));
                  UCB1CTLW0 |= UCTXSTP;      // Send stop condition
              }
              break;

          case TX_DATA_MODE:
              if (ui8TXByteCounter)
              {
                  UCB1TXBUF = ui8TransmitBuffer[ui8TransmitIndex++];
                  ui8TXByteCounter--;
              }
              else
              {
                  //Done with transmission
                  UCB1CTLW0 |= UCTXSTP;     // Send stop condition
                  MasterMode = IDLE_MODE;
                  UCB1IE &= ~UCTXIE;                       // disable TX interrupt
                  __bic_SR_register_on_exit(CPUOFF);      // Exit LPM0
              }
              break;

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

Please Help me with this at the earliest.

Thanks and Regards.

Utkarash

I just realized that I've been looking at the schematics for the CAPTIVATE-2633 (linked from the CAPTIVATE-2676 page (!)), which doesn't have UCB1 nor P4. I haven't been able to find the correct schematics, so as a result I'm kind of working blind.

Since you've apparently figured this out already, I have to ask you: How have you connected to UCB1/P4.3-4? I'm concerned in particular about the pullups which are supplied outbound (MSP_SDA/_SCL) -- are they connected to your circuit? If your I2C bus were lacking pullups, you would see this sort of symptom.

In many cases the internal pullups can suffice (if the wires are very short, and you don't run the bus too fast). A quick experiment might be to add:

> P4OUT |= (BIT3|BIT4); // Engage

> P4REN |= (BIT3|BIT4); //     internal pullups -- maybe they'll work

Since you've apparently figured this out already, I have to ask you: How have you connected to UCB1/P4.3-4? I'm concerned in particular about the pullups which are supplied outbound (MSP_SDA/_SCL) -- are they connected to your circuit? If your I2C bus were lacking pullups, you would see this sort of symptom.

-- I have connected 4.7 k Pullup register to SCL and SDA pins which were recommended in "msp430fr267x_eusci_i2c_standard_master.c" example code. 

Also when i interface the sensor on eUSCB0 pins of I2C (i.e., P1.2 and P1.3) i was able to communicate, however when i interfaced sensor on eUSCB1 pin of I2C (i.e., P4.3 and P4.4) i am not able to interface the same.

In many cases the internal pullups can suffice (if the wires are very short, and you don't run the bus too fast). A quick experiment might be to add:

-- I tried without pullup register, However still my issues remains the same.

Please help where i am missing out ?

Thanks and regards