[资料分享] MSP430 - G2553之串口操作

fish001 2017-9-15 22:48 楼主

#include

void delay1s(void)
{
  int t = 1000;
  while (t--)
__delay_cycles(1000);
}

#define UART_TXD 0x02                               // TXD on P1.1 (Timer0_A.OUT0)

#define UART_TBIT (1000000 / 9600)                   // 9600 Baud, SMCLK = 1MHz
                                                   // Globals for transmit UART communication
unsigned int txData;                                  // UART internal variable for TX

void TimerA_UART_tx(unsigned char byte);             // Function prototypes
void TimerA_UART_print(char *string);

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                         // Stop watchdog timer
  DCOCTL = 0x00;                                     // Set DCOCLK to 1MHz
  BCSCTL1 = CALBC1_1MHZ;
  DCOCTL = CALDCO_1MHZ;

  P1OUT = UART_TXD;                                  // Initialize P1.1
  P1SEL = UART_TXD;                                  // Timer function for TXD pin
  P1DIR = UART_TXD;                                  // Set TXD pin to output
                                                   // Timer_A for transmit UART operation
  TA0CCTL0 = OUT;                                     // Set TXD Idle as Mark = '1'
  TA0CCTL1 = SCS + CM1 + CAP;                         // Sync, Neg Edge, Capture
  TA0CTL = TASSEL_2 + MC_2;                         // SMCLK, start in continuous mode

  P2DIR |= (BIT3 | BIT4);                      //Set P1.0 and P1.6 to outputs

  _BIS_SR(GIE);                                     // Enable CPU interrupts

  while (1) {
TimerA_UART_print("G2553 TimerA UART\r\n");       // Send test message
TimerA_UART_print("READY.\r\n");
P2OUT ^= 0x18;
delay1s();
  }
}

void TimerA_UART_tx(unsigned char byte)             // Outputs one byte using the Timer_A UART
{
  while (TACCTL0 & CCIE);                            // Ensure last char got TX'd

  TA0CCR0 = TAR;                                     // Current state of TA counter
  TA0CCR0 += UART_TBIT;                               // One bit time till first bit
  txData = byte;                                     // Load transmit data, e.g. 'A'=01000001
  txData |= 0x100;                                  // Add mark stop bit, e.g. 101000001
  txData <<= 1;                                     // Add space start bit, e.g. 1010000010
  TA0CCTL0 = OUTMOD0 + CCIE;                         // Set TXD on, enable counter interrupt
}

void TimerA_UART_print(char *string) {                // Prints a string using the Timer_A UART
  while (*string)
TimerA_UART_tx(*string++);
}

#pragma vector = TIMER0_A0_VECTOR                   // Timer_A UART - Transmit ISR

__interrupt void Timer_A0_ISR(void) {
  static unsigned char txBitCnt = 10;
  TA0CCR0 += UART_TBIT;                               // Add Offset to CCRx

  if (txBitCnt == 0) {                               // All bits TXed?
TA0CCTL0 &= ~CCIE;                               // All bits TXed, disable interrupt
txBitCnt = 10;                                  // Re-load bit counter
  }
  else {
if (txData & 0x01)
   TA0CCTL0 &= ~OUTMOD2;                         // TX Mark '1'
else
   TA0CCTL0 |= OUTMOD2;                            // TX Space '0'
  }
  txData >>= 1;                                     // Shift right 1 bit (low bits TX'ed first)
  txBitCnt--;
}