msp430f5529 的UART模块485通讯问题

你好，我想问下我这程序有什么问题，为什么老是出错。我是想让程序每一秒发一组数据，receive_Data才4个数据，但是i==6才能发送出5个数据“0xf0 0xf1 0xf2 0xf3 0xfe”如果i==5的话又变成“0xf0 0xf1 0xf2 0xfe”了。。。用的MAX3485连接MPU，再转成RS232到电脑上的串口调试程序。如果我想接收和发送多个数据，我应该怎么配置寄存器？发送和接收多个数据是进一次中断还是进多个（数据的字节数）中断？

#include <msp430.h>
#include "UCA0_UART.h"
#include "TIMER_A0.h"

void main()
{
WDTCTL = WDTPW + WDTHOLD;
UCA0_Init();
TIMERA0_Init();
_EINT();

while(1);

}

#include <msp430.h>
#include "TIMER_A0.h"
#include "UCA0_UART.h"

/******************************
名 称：TIMERA0_Init
功 能：初始化TIMERA0寄存器操作
参 数：无
返 回：无
******************************/
void TIMERA0_Init(void)
{
P8DIR |= BIT0;
TA0CCR0 = 32768-1;
TA0CTL = TASSEL_1 + MC_1 + TACLR + TAIE; // ACLK, contmode, clear TAR
// enable interrupt
}

#pragma vector=TIMER0_A1_VECTOR
__interrupt void TIMER0_A1_ISR(void)
{
switch(__even_in_range(TA0IV,14))
{
case 0: break; // No interrupt
case 2: break; // CCR1 not used
case 4: break; // CCR2 not used
case 6: break; // reserved
case 8: break; // reserved
case 10: break; // reserved
case 12: break; // reserved
case 14: // overflow
P8OUT ^= BIT0;
RS485_T;
UCA0IE |= UCTXIE;
break;
default: break;
}
}

#include <msp430.h>
#include "UCA0_UART.h"

unsigned char receive_Data[4] = {0x00,0x00,0x00,0x00};
unsigned char transmit_Data[4] = {0xf0,0xf1,0xf2,0xf3};

unsigned char i = 0;

/******************************
名 称：UCA0_Init
功 能：初始化UCA0寄存器操作，波特率9600，奇偶校验位无，数据位8位，停止位1位，
参 数：无
返 回：无
******************************/
void UCA0_Init(void)
{
P3SEL = BIT3 + BIT4;
UCA0CTL1 |= UCSWRST;
UCA0CTL1 |= UCSSEL_2; // SMCLK = 1.048576MHz
UCA0BR0 = 6; // 1.048576MHz 9600 N = 1.048576/(16*9600 )= 6
UCA0BR1 = 0; // 1.048576MHz 9600
UCA0MCTL |= UCBRS_0 + UCBRF_13 + UCOS16; // Modulation UCBRSx=1, UCBRFx=0
// over sampling
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
UCA0IE |= UCRXIE; // Enable USCI_A0 RX interrupt


RS485_OUT;
RS485_R;

}

#pragma vector=USCI_A0_VECTOR
__interrupt void USCI_A0_ISR(void)
{
switch(__even_in_range(UCA0IV,4))
{
case 0:break;
case 2:
case 4:
while(UCA0IFG&UCTXIFG);

TA0CTL &=~ TAIE;
UCA0IE &=~ UCRXIE;
UCA0TXBUF = transmit_Data[i++];
if(i == 4)
{
i = 0;
UCA0IFG &=~ UCTXIFG;
UCA0IE &=~ UCTXIE;
TA0CTL |= TAIE;
RS485_R;
return;
}

break;
default: break;
}
}