Hi,
I hope someone can help. I have been working with the MSP430F2274 and 38-pin dev board. I am trying to program the mcu to work with a sensor through i2c. I have had success using the example code which is posted below. My problem just started today. The sensor and mcu were communicating just fine through i2c and I did something that caused a permanent problem and the interrupts no longer seem to be working. I have created new projects and copied the original example files into the project and still the same error. Re-installed ccs. Changed out chips on the dev. board and no success.
Stepping through the code:
Within the while loop the debugger hangs after the __bis_SR_register(CPUOFF + GIE);, and sits at the following instruction. I assume the error has something to do with the low power mode. If I remove the CPUOFF in the above function, I can step through the code but still no interrupt occurs.
I believe that my problem originated from me changing the interrupt function from void to USHORT and compiling and debugging. Which I now know is a no no. Is there a global file that needs to be deleted to restore defaults?
Thank you,
The code below is identical to the example code for the i2c for the 2274.
#include "msp430x22x4.h"
unsigned int RxByteCtr;
unsigned int RxWord;
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= 0x01; // P1.0 output
P3SEL |= 0x06; // 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 = 0x40; // 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
// Remain in LPM0 until all data
// is RX'd
__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 = TIMERA0_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
}
}