Hello;
I am using XMS430F5438 for developing my new application. For validation od code, i am using MSP-EXP430F5438 development board. My program is as follows:
#include
volatile
volatile
void
WDTCTL = WDTPW | WDTHOLD;
// Stop WDT
P3SEL = 0x30;
// P3.4,5 = USCI_A0 TXD/RXD
UCA0CTL1 |= UCSWRST;
// **Put state machine in reset**
UCA0CTL1 |= UCSSEL_1;
// CLK = ACLK
UCA0BR0 = 0x03;
// 32kHz/9600=3.41 (see User's Guide)
UCA0BR1 = 0x00;
//
UCA0MCTL = UCBRS_3 | UCBRF_0;
// Modulation UCBRSx=3, UCBRFx=0
UCA0CTL1 &= ~UCSWRST;
// **Initialize USCI state machine**
UCA0IE |= UCRXIE;
// Enable USCI_A0 RX interrupt
UCA0IE |= UCTXIE;
// Enable USCI_A0 RX interrupt
for (i = 0; i <= 40; i++);
__bis_SR_register(LPM0_bits + GIE);
// Enter LPM0, interrupts enabled
__no_operation();
// For debugger
}
// Echo back RXed character, confirm TX buffer is ready first
#pragma
void USCI_A0_ISR(void)
{
switch (__even_in_range(UCA0IV,4))
{
case 0: break;
// Vector 0 - no interrupt
case 2:
// Vector 2 - RXIFG
// while (!(UCA0IFG & UCTXIFG)); // USCI_A0 TX buffer ready ? // while (!UCRXIFG); // USCI_A0 TX buffer ready ?
Rx_Data = UCA0RXBUF;
// TX -> RXed character
break;
case 4: UCA0TXBUF = 0x6A;
// TX -> 0x5A character
// while (!UCTXIFG); // USCI_A0 TX buffer ready ?
break;
// Vector 4 - TXIFG
default: break;
}
}
This program transmits character on UART. The program works as follows:
1. UART is configured to communicate at 9600 baud. UART works on ACLK = 32.768 Hz. 38768/9600 = 3.41.
2. After the UART is configured for communication at 9600 baud, an interrupt occurs. Hence an ISR is called by reading UCA0IV register through __interrupt intrinsic of CCSV4. In the ISR, condition 4 is satisfied and 0x6A is transmitted on UART only once. After the character transfer, the program control should come out of ISR and return to main () function. But this is not happening.
vector = USCI_A0_VECTOR__interrupt
RS232_UART (void){
unsigned int i;
unsigned int Rx_Data;"xms430f5438.h"
#include
"RS232_UART.h"
My problem is as follows:
1. The program control does not comes out of ISR. It loops inside the ISR indefinitely and does not return to main () function. I have checked following registers:
UCA0IV --- At the end of ISR UCA0IV = 0x0000
UCATXIFG --- At the end of ISR UCATXIFG = 0
After this the program control returns to __interrupt statement at the beginning of the program.
How to solve this problem, what is wrong in this program ?
Thanks in Advance...
--- Sunil
