I wrote the following code: #include /* * main.c */ signed char size; unsigned char *dataReceive; unsigned char *dataTransmit; unsigned char slaveAddr = 0x20; int main(void) { WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer P1SEL |= BIT7 + BIT6; // SET SDA + SCL Functions P1SEL2 |= BIT7 + BIT6; // SET SDA + SCL Functions UCB0CTL1 |= UCSWRST; //reset UCB0CTL0 |= UCMST + UCMODE_3 + UCSYNC; // I2C SYNC MASTER MODE UCB0BR0 = 0x08; UCB0BR1 = 0; UCB0I2CSA = slaveAddr; UCB0CTL1 |= UCSSEL_3 + UCSWRST; // SMCLK UCB0CTL1 &= ~UCSWRST; //resume operation UCB0I2CIE |= UCNACKIE; IE2 |= UCB0TXIE + UCB0RXIE; // Enable TX & RX interrupt dataTransmit = "Hello"; size = 5; while(UCB0STAT & UCBBUSY);//waiting for master stop being busy UCB0CTL1 |= UCTR + UCTXSTT; // set transmitter and start condition __bis_SR_register(GIE); while(1){ } return 0; } #pragma vector = USCIAB0RX_VECTOR __interrupt void USCIAB0RX_ISR(void) { if (UCB0STAT & UCNACKIFG){ // send STOP if slave sends NACK UCB0CTL1 |= UCTXSTP; UCB0STAT &= ~UCNACKIFG; } } #pragma vector = USCIAB0TX_VECTOR __interrupt void USCIAB0TX_ISR(void) { if (IFG2 & UCB0RXIFG){ if ( size == 0 ){ UCB0CTL1 |= UCTXSTP; // I2C stop condition *dataReceive = UCB0RXBUF; dataReceive++; } else { *dataReceive = UCB0RXBUF; dataReceive++; size--; } } else { if (size == 0){ UCB0CTL1 |= UCTXSTP; // I2C stop condition IFG2 &= ~UCB0TXIFG; // Clear USCI_B0 TX int flag } else { UCB0TXBUF = *dataTransmit; dataTransmit++; size--; } } } And i have those questions: 1.When i'm wiriting the lines: P1SEL |= BIT7 + BIT6; // SET SDA + SCL Functions P1SEL2 |= BIT7 + BIT6; // SET SDA + SCL Functions the code is stuck in this line: while(UCB0STAT & UCBBUSY); which means that the UCBBUSY bit is high. but when i omit one of the P1SEL lines the code doesn't stuck ( UCBBUSY bit is low) why this is happens? 2. after it passes the while "busy" loop it's running the interrupt event once which takes only one character and doesn't show it on the slave(lcd), i assume that the interrupt will run untill it get stop bit(UCTXSTP) and the flag is clear (UCB0TXIFG) but it doesn't 3. how to compute the smclk communication speed? i searched, but didn't find nothing. The slave address is the correct address. Thank you.
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