Compiler/MSP430F67641A: UART interrupt is not triggering

Hello Satish,

In the future, please post your code using the Syntax Highlighter icon below. Without it, the code is hard to read and there's probably a lower chance that our community members will look through it and provide recommendations. I went ahead and fixed your initial post above.

Regarding your question, I don't see where you enable global interrupts. Also, it looks like you're using ACLK, but I don't see any XT1 setup code. So, there could be an oscillator fault flag that doesn't get cleared.

satish sharma13 said:

my issue is my uart interrupt is not triggering  i have selected this pins as pheripheral  P2SEL|= BIT2 + BIT3; 

Where does the code halt? Are your UART connections correct? Initialize your pins before configuring the UART module.

satish sharma13 said:

suggest me the answer as soon as possible because i m running out of time on this project ..

I would highly recommend using one of our code examples as a reference. If it works, add your changes piece-by-piece until something doesn't work. Then, figure out why that change causes the issue. Preferably, you won't have any issues if all the changes are correct.

msp430f67641A_uscia0_uart_03.c

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 * for an API functional library-approach to peripheral configuration.
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//******************************************************************************
//   MSP430F67641A Demo - USCI_A0, Ultra-Low Power UART 9600 Echo ISR, 32kHz ACLK
//
//   Description: Echo a received character, RX ISR used. Normal mode is LPM3,
//   USCI_A0 RX interrupt triggers TX Echo.
//   ACLK = 32768Hz crystal, MCLK = SMCLK = DCO ~1.045MHz
//   Baud rate divider with 32768Hz XTAL @9600 = 32768Hz/9600 = 3.41
//   See User Guide for baud rate divider table
//
//
//               MSP430F67641A
//             -----------------
//        /|\ |              XIN|-
//         |  |                 | 32kHz
//         ---|RST          XOUT|-
//            |                 |
//            |     P1.3/UCA0TXD|------------>
//            |                 | 9600 - 8N1
//            |     P1.2/UCA0RXD|<------------
//
//  E. Chen
//  Texas Instruments Inc.
//  January 2015
//  Built with CCS Version: 5.5.0 and IAR Embedded Workbench Version: 5.52
//******************************************************************************
#include <msp430.h>

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;               // Stop WDT

    // Setup P1.2 UCA0RXD, P1.3 UCA0TXD
    P1SEL |= BIT2 | BIT3;                   // Set P1.2, P1.3 to non-IO
    P1DIR |= BIT2 | BIT3;                   // Enable UCA0RXD, UCA0TXD

    // Setup LFXT1
    UCSCTL6 &= ~(XT1OFF);                   // XT1 On
    UCSCTL6 |= XCAP_3;                      // Internal load cap
    // Loop until XT1 fault flag is cleared
    do
    {
        UCSCTL7 &= ~(XT2OFFG | XT1LFOFFG | DCOFFG);
        // Clear XT2,XT1,DCO fault flags
        SFRIFG1 &= ~OFIFG;                  // Clear fault flags
    } while (SFRIFG1 & OFIFG);              // Test oscillator fault flag

    // Setup eUSCI_A0
    UCA0CTLW0 |= UCSWRST;                   // **Put state machine in reset**
    UCA0CTLW0 |= UCSSEL_1;                  // CLK = ACLK
    UCA0BRW_L = 0x03;                       // 32kHz/9600=3.41 (see User's Guide)
    UCA0BRW_H = 0x00;                       //
    UCA0MCTLW = 0x5300;                     // Modulation UCBRSx=0x53, UCBRFx=0
    UCA0CTLW0 &= ~UCSWRST;                  // **Initialize USCI state machine**
    UCA0IE |= UCRXIE;                       // Enable USCI_A0 RX interrupt

    __bis_SR_register(LPM3_bits | GIE);     // Enter LPM3, interrupts enabled
    __no_operation();                       // For debugger
}

// USCI_A0 interrupt service routine
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_A0_VECTOR
__interrupt void USCI_A0_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_A0_VECTOR))) USCI_A0_ISR (void)
#else
#error Compiler not supported!
#endif
{
    switch (__even_in_range(UCA0IV, 4))
    {
        case USCI_NONE: break;              // No interrupt
        case USCI_UART_UCRXIFG:             // RXIFG
            while (!(UCA0IFG & UCTXIFG)) ;  // USCI_A0 TX buffer ready?
            UCA0TXBUF = UCA0RXBUF;          // TX -> RXed character
            break;
        case USCI_UART_UCTXIFG: break;      // TXIFG
        case USCI_UART_UCSTTIFG: break;     // TTIFG
        case USCI_UART_UCTXCPTIFG: break;   // TXCPTIFG
        default: break;
    }
}

Regards,

James

dear sir,

i am using uca2rxd module for reception of data ...which is pin number p2.2..

and i give some voltage which is 3.2v through a register to this pin it is going to zero means voltage accross this is zero..