Problem setting UART interruption in MSP430FG4618

Do you globally enable interrupts at all? (e.g. with _EINT() or _bis_SR_register(GIE) or such)

If you enable itnerrupts globally, and enable RX interrupt, and do not have an ISR for it, the CPU will crash.

If you have the ISR, it should be called when a byte was received. However, it should read RSBUF or at least clear RXIFG befor exiting. Or it will be called over and over again, stopping main.

Thanks for answering. About the question, I have enabled the interruptions using _EINT() or _bis_SR_registers(GIE).

According to your comment, I have a ISR for it, which is the following:

#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR (void)
{
       while( IFG2 & UCA0RXIFG );
       {
             ......
       } 
       IFG2 &= ~UCA0RXIFG;
}

And even that it does not work.

More suggestion would be great, thanks in advance.

gus.

gchaconr said:

       while( IFG2 & UCA0RXIFG );
       {
             ......
       } 
       IFG2 &= ~UCA0RXIFG;

This is too much. When the while loop exits, UCA0RXIFG is clear. If you manually clerar it then, you best case do a NOP, but worst case clear teh signal that another byte has just arrived.
And if the RXIFG bti is not cleare dinside the while (w.g. by reading RXBUF), then the while will loop forever anyway.

However, the ISR should be called as soon as a byte arrived.

By the way, I am using "BSP_Init()" from Simpliciti at the beginning of the code to init the MSP430FG4618, and immediately after that I use this function:

void McuInit(void)
{
    _DINT();
    WDTCTL = WDTPW + WDTHOLD;               //Stop WDT
    FLL_CTL0 = (DCOPLUS | XCAP18PF);       //Enable Frequency Multiplier (DCO+) and XIN/XOUT caps to 18pF
    SCFI0 = (FLLD_2 | FN_8);               //Set Multiplier to 2, and DCO range to 8MHz nominal
    SCFQCTL = 121;                         //7.995392Mhz Operation with No Modulation
    
    UartInit();
    _EINT();
}

to make sure that the UART works as I expect. I am not sure if this could be problem, but when I comment the line "IE2 |= UCA0RXIE;" I do not have any problem in communication via using Simpliciti and via the UART port.

Thanks in advance for any suggestion.

gus

#include <msp430xg46x.h>

int main(void)
{
  volatile unsigned int i;

  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  P4SEL |= 0x03;                            // P4.1,0 = USART1 TXD/RXD
  FLL_CTL0 |= XCAP14PF;                     // Configure load caps

  do
  {
  IFG1 &= ~OFIFG;                           // Clear OSCFault flag
  for (i = 0x47FF; i > 0; i--);             // Time for flag to set
  }
  while ((IFG1 & OFIFG));                   // OSCFault flag still set?

  ME2 |= UTXE1 + URXE1;                     // Enable USART1 TXD/RXD
  U1CTL |= CHAR;                            // 8-bit character
  U1TCTL |= SSEL1 + SSEL0 + URXSE;          // UCLK = SMCLK, start edge detect
  U1BR0 = 0x37;                             // 1MHz 19200
  U1BR1 = 0x00;                             // 1MHz 19200
  U1MCTL = 0x6B;                            // 1MHz 19200 modulation
  U1CTL &= ~SWRST;                          // Initialize USART state machine
  IE2 |= URXIE1;                            // Enable USART1 RX interrupt

  for (;;)
  {
    while (!(U1TCTL & TXEPT));              // Confirm no TXing before --> LPM3
    _DINT();                                // Disable interrupts for flag test
    _NOP();
    if (!(U1TCTL & SSEL0))
     _BIS_SR(LPM0_bits + GIE);              // RX'ing char, LPM, int's active
    else
     _BIS_SR(LPM3_bits + GIE);              // Enter LPM3, int's active
  }
}

#pragma vector=USART1RX_VECTOR
__interrupt void usart1_rx (void)
{
  if ((IFG2 & URXIFG1))                     // Test URXIFG0
  {
    while (!(IFG2 & UTXIFG1));              // USART1 TX buffer ready?
    U1TXBUF = U1RXBUF;                      // RXBUF0 to TXBUF0
    _BIC_SR_IRQ(LPM3_bits);                 // Exit LPM3 after reti
    U1TCTL |= SSEL0;                        // SSEL0 = 1, no RX activity
  }
  else                                      // Start edge
  {
    U1TCTL &= ~URXSE;                       // Clear URXS signal
    U1TCTL |= URXSE;                        // Re-enable edge detect
    _BIC_SR_IRQ(SCG1 + SCG0);               // DCO reamins on after reti
    U1TCTL &= ~SSEL0;                       // SSEL0= 0, RX activity
  }
}
 

use this code this is verifed so set boad rate at 9600

vasant mangale

mit coe

alandi pune

Thanks for the code you posted, but it didn't work at all.

gchaconr said:

I am using "BSP_Init()" from Simpliciti at the beginning of the code to init the MSP430FG4618, and immediately after that I use this function:

I don't have any experience with SimpliciTI, so I cannot help you there.

Thanks for answering, but I have finally found the problem.

I changed the ISR as follows:

#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIA0RX_ISR (void)
{
       if( IFG2 & UCA0RXIFG )
       {
             ......

            IFG2 &= ~UCA0RXIFG;
       } 
}

and with that the interruption problem is solved, instead of using the previous code which will keep running a while loop forever in the ISR. I think someone made a comment before about that but I didn't realize it until now.