msp430硬件IIC读写AT24C02，采用轮询方式

void delay(void)
{
    unsigned char i, j;
    for(i = 0; i < 255; i++)
        for(j = 0; j < 255; j++);
}

void i2c_init(void)
{
    WDTCTL = WDTPW + WDTHOLD; // Stop WDT
    P3SEL |= 0x06; // Assign I2C pins to USCI_B0
    UCB0CTL1 |= UCSWRST; // Enable SW reset
    UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
    UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
    UCB0BR0 = 11; // fSCL = SMCLK/11 = 95.3kHz
    UCB0BR1 = 0;
    UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
}

void wr_at24c02(unsigned char slave_addr, unsigned char addr, unsigned char *buf, unsigned char len)
{
    int i,j;

    UCB0I2CSA = slave_addr;
    UCB0CTL1 |= (UCTXSTT | UCTR);
    while(!(IFG2 & UCB0TXIFG));
    UCB0TXBUF = addr;
    while(UCB0CTL1 & UCTXSTT);
    while(!(IFG2 & UCB0TXIFG));


    for(i = 0; i < len; i++) {
        UCB0TXBUF=buf[i];
        if(i != len-1)
         while(!(IFG2 & UCB0TXIFG));
        if(i == len-2) {
            UCB0CTL1 |= UCTXSTP;
        }
    }

    delay();
}

void rd_at24c02(unsigned char slave_addr, unsigned char addr, unsigned char *buf, unsigned char len)
{
    int i,j;

    UCB0I2CSA = slave_addr;
    UCB0CTL1 |= (UCTXSTT | UCTR);

    while(!(IFG2 & UCB0TXIFG));
    UCB0TXBUF = addr;

    while(UCB0CTL1 & UCTXSTT);
    while(!(IFG2 & UCB0TXIFG));

    UCB0I2CSA = slave_addr;
    UCB0CTL1 &= ~UCTR;
    UCB0CTL1 |=UCTXSTT;
    while(UCB0CTL1 & UCTXSTT);
    for(i = 0; i < len; i++) {
        while(!(IFG2 & UCB0RXIFG));
        buf[i] = UCB0RXBUF;
        if(i == len-2) {
            UCB0CTL1 |= UCTXSTP;
        }
    }

    delay();
}

unsigned char a[8];
unsigned char b[8]={0,1,2,3,4,5,6,7};
int main()
{
     i2c_init();
     wr_at24c02(0x50, 0x00, b, 8);
     rd_at24c02(0x50, 0x00, a, 8);
     while(1);
}