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MCU与bq76PL455之间的UART通信存在延迟

最近在学习使用455,,参考TI的例程编写455的初始化函数,代码如下:

void main(void)
{    
    INT8U nSent;

    PLL_Init();     
    IO_init();          
    delayms(5);
    WakeUpPL455();
    delayms(5);

    COMM_RESET();
    SCI_init();

    nSent = WriteCommand(0, 12, 0x40, 1, Broadcast_Write);    
    delayms(10);
    WakeUpPL455();
    delayms(10);

    //清除故障标志
    //                 ID, Register, Data, Length, Command
    nSent = WriteCommand(0, 107, 0x8000, 2, Broadcast_Write); //
    nSent = WriteCommand(0, 82, 0xFFC0, 2, Broadcast_Write); // clear all fault summary flags
    nSent = WriteCommand(0, 81, 0x38, 1, Broadcast_Write); //  clear fault flags in the system status register

    //设置455地址
    nSent = WriteCommand(0, 14, 0x19, 1, Broadcast_Write); // set auto-address mode on all boards
    nSent = WriteCommand(0, 12, 0x08, 1, Broadcast_Write); //  enter auto address mode on all boards, the next write to this ID will be its address
    nSent = WriteCommand(0, 10, 0, 1, Broadcast_Write); // 设置455的地址为0
        
    //清除故障标志
    nSent = WriteCommand(0, 82, 0xFFC0, 2, Broadcast_Write);    // clear all fault summary flags
    nSent = WriteCommand(0, 81, 0x38, 1, Broadcast_Write); //  clear fault flags in the system status register

    //设置通信
    nSent = WriteCommand(0, 16, 0x1080, 2, Single_Write); //使能UART发送和FAULT_N输出

    //清除故障标志
    nSent = WriteCommand(0, 82, 0xFFC0, 2, Broadcast_Write); // clear all fault summary flags
    nSent = WriteCommand(0, 81, 0x38, 1, Broadcast_Write); //  clear fault flags in the system status register

    while(1)
    {
        nSent = WriteCommand(0, 10, 0, 1, Single_Read); //读ID为0的455的地址
        delayms(500);

    }
}

主函数最后,我用while死循环连续读取455的地址,但是刚开始MCU发的几次读取地址的指令,455没有响应,一段时间后455才开始回信息,并且返回的信息是正确的,在示波器上显示如下:

想请教各位大神,为什么455刚开始没有向MCU回复信息?谁遇到过这种情况?