ARM LPC2378 I2C与HMC5883L接口

Question

我试图将LPC2378 I2C0与HMC5883L连接。我写了以下代码：

main () {

    lcd_init();
    lcd_clear();

    PINSEL1 |= 0x01400000;
    I20CONCLR =0x6c; //Clear all flags
    I20CONSET=0X40;  //Enable the interface. 
    I20SCLH=I20SCLL=60; //100 KHz

    VICIntEnable |= 0x0000200; 
    VICVectPriority9 = 1;
    VICVectAddr9 = (unsigned long)ISR_I2C;

    I20CONSET=0X60; //to send Start bit
    while(1)
    {
        // Idle state. Waiting for interrupts.    
    }

}

__irq void ISR_I2C(void) {
    int status;
    status=I20STAT;
    if(status==0X08) 
    {
        I20DAT=0x3C; // Slave address + R/W bit
        lcd_print("Hello"); 
        I20CONCLR=0x28; //start, interrupt clear
    }
    if(status==0X18) 
    {
        I20DAT=0x02;    //Slave ACK, Send data byte
        lcd_print("ACK");
        I20CONCLR=0x08; // interrupt clear
    }
    if(status==0X20) 
    {
        lcd_print("NACK");
        I20CONCLR=0x08; // interrupt clear
    }

    VICVectAddr = 0;

} 

当我在模拟中运行时（在Keil中），我得到了NACK条件（由于没有从器件确认，这是预期的），但是当我连接到HMC5883L时，我在传输后没有达到ACK或NACK状态SLA + W字节。造成这个问题的原因是什么？