I2C on MSP 430F5529

Other Parts Discussed in Thread: BQ24272, MSP430F2274, MSP430WARE

I need to do I2C with a Bq24272 chip.  I was able to do it with an arduino and read the required registers. I need to do the same using MSP 430 F5529. Is there a modular library available for the same? Since communicating between the MSP and the Bq chip would require a lot of sending and receiving using I2C, I tried to use the sample codes available on TI's website first. I used the sample code for Master_send and Slave_receive available on the website to try to communicate between two MSP4305529s. But when I put the oscilloscope on the SCL line, I did not get any pulses. My board did not have the UCSIB0 pins available so I had changed the codes to implement I2C using the UCSIB1 pins. Was the error caused by this?

The changed code is as follows:

Master as Transmitter:

#include <msp430.h>

unsigned char TXData;
unsigned char TXByteCtr;

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P4SEL |= 0x06; // Assign I2C pins to USCI_B0
UCB1CTL1 |= UCSWRST; // Enable SW reset
UCB1CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB1CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB1BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB1BR1 = 0;
UCB1I2CSA = 0x48; // Slave Address is 048h
UCB1CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB1IE |= UCTXIE; // Enable TX interrupt

TXData = 0x01; // Holds TX data

while (1)
{
TXByteCtr = 1; // Load TX byte counter

while (UCB1CTL1 & UCTXSTP); // Ensure stop condition got sent
UCB1CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition

__bis_SR_register(LPM0_bits + GIE); // Enter LPM0 w/ interrupts
__no_operation(); // Remain in LPM0 until all data
// is TX'd

TXData++; // Increment data byte
}
}

//------------------------------------------------------------------------------
// The USCIAB0_ISR is structured such that it can be used to transmit any
// number of bytes by pre-loading TXByteCtr with the byte count.
//------------------------------------------------------------------------------
#pragma vector = USCI_B1_VECTOR
__interrupt void USCI_B1_ISR(void)
{
switch(__even_in_range(UCB1IV,12))
{
case 0: break; // Vector 0: No interrupts
case 2: break; // Vector 2: ALIFG
case 4: break; // Vector 4: NACKIFG
case 6: break; // Vector 6: STTIFG
case 8: break; // Vector 8: STPIFG
case 10: break; // Vector 10: RXIFG
case 12: // Vector 12: TXIFG
if (TXByteCtr) // Check TX byte counter
{
UCB1TXBUF = TXData; // Load TX buffer
TXByteCtr--; // Decrement TX byte counter
}
else
{
UCB1CTL1 |= UCTXSTP; // I2C stop condition
UCB1IFG &= ~UCTXIFG; // Clear USCI_B0 TX int flag
__bic_SR_register_on_exit(LPM0_bits); // Exit LPM0
}
break;
default: break;
}
}

Slave as Receiver:

#include <msp430.h>

volatile unsigned char RXData;

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P4SEL |= 0x06; // Assign I2C pins to USCI_B0
UCB1CTL1 |= UCSWRST; // Enable SW reset
UCB1CTL0 = UCMODE_3 + UCSYNC; // I2C Slave, synchronous mode
UCB1I2COA = 0x48; // Own Address is 048h
UCB1CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB1IE |= UCRXIE; // Enable RX interrupt

while (1)
{
__bis_SR_register(LPM0_bits + GIE); // Enter LPM0, enable interrupts
__no_operation(); // Set breakpoint >>here<< and read
} // RXData
}

// USCI_B0 Data ISR
#pragma vector = USCI_B1_VECTOR
__interrupt void USCI_B1_ISR(void)
{
switch(__even_in_range(UCB1IV,12))
{
case 0: break; // Vector 0: No interrupts
case 2: break; // Vector 2: ALIFG
case 4: break; // Vector 4: NACKIFG
case 6: break; // Vector 6: STTIFG
case 8: break; // Vector 8: STPIFG
case 10: // Vector 10: RXIFG
RXData = UCB1RXBUF; // Get RX data
__bic_SR_register_on_exit(LPM0_bits); // Exit LPM0
break;
case 12: break; // Vector 12: TXIFG
default: break;
}
}