底下為範例程式
UART中斷不用清除旗標嗎?
1.是只要讀取UCA0TXBUF或UCA0RXBUF，相對應旗標就會自動被清除嗎?
2.如果我沒開啟中斷，接收到字元的話UCRXIFG是否也會被立起來?
#include <msp430.h>
void Init_GPIO();
int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer
// Configure GPIO
Init_GPIO();
PM5CTL0 &= ~LOCKLPM5; // Disable the GPIO power-on default high-impedance mode
// to activate 1previously configured port settings
__bis_SR_register(SCG0); // disable FLL
CSCTL3 |= SELREF__REFOCLK; // Set REFO as FLL reference source
CSCTL0 = 0; // clear DCO and MOD registers
CSCTL1 &= ~(DCORSEL_7); // Clear DCO frequency select bits first
CSCTL1 |= DCORSEL_3; // Set DCO = 8MHz
CSCTL2 = FLLD_0 + 243; // DCODIV = 8MHz
__delay_cycles(3);
__bic_SR_register(SCG0); // enable FLL
while(CSCTL7 & (FLLUNLOCK0 | FLLUNLOCK1)); // Poll until FLL is locked
CSCTL4 = SELMS__DCOCLKDIV | SELA__REFOCLK; // set default REFO(~32768Hz) as ACLK source, ACLK = 32768Hz
// default DCODIV as MCLK and SMCLK source
// Configure UART pins
P1SEL0 |= BIT4 | BIT5; // set 2-UART pin as second function
// Configure UART
UCA0CTLW0 |= UCSWRST;
UCA0CTLW0 |= UCSSEL__SMCLK;
// Baud Rate calculation
// 8000000/(16*9600) = 52.083
// Fractional portion = 0.083
// User's Guide Table 14-4: UCBRSx = 0x49
// UCBRFx = int ( (52.083-52)*16) = 1
UCA0BR0 = 52; // 8000000/16/9600
UCA0BR1 = 0x00;
UCA0MCTLW = 0x4900 | UCOS16 | UCBRF_1;
UCA0CTLW0 &= ~UCSWRST; // Initialize eUSCI
UCA0IE |= UCRXIE; // Enable USCI_A0 RX interrupt
__bis_SR_register(LPM3_bits|GIE); // Enter LPM3, interrupts enabled
__no_operation(); // For debugger
}
#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,USCI_UART_UCTXCPTIFG))
{
case USCI_NONE: break;
case USCI_UART_UCRXIFG:
while(!(UCA0IFG&UCTXIFG));
UCA0TXBUF = UCA0RXBUF;
__no_operation();
break;
case USCI_UART_UCTXIFG: break;
case USCI_UART_UCSTTIFG: break;
case USCI_UART_UCTXCPTIFG: break;
default: break;
}
}
void Init_GPIO()
{
P1DIR = 0xFF; P2DIR = 0xFF; P3DIR = 0xFF;
P1REN = 0xFF; P2REN = 0xFF; P3REN = 0xFF;
P1OUT = 0x00; P2OUT = 0x00; P3OUT = 0x00;
}