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求教：F28335 上电后XINTF有时读写不正常的问题

yanwei zhang
Prodigy 80 points


  使用F28335的XINTF连接了TL16C754来扩展串口，使用稳压电源给板子加电后，XINTF读写有时正常，有时不正常；不正常时XINTF数据位用示波器能量到比脉宽比正常时窄的波形信号，但不是正确的数据。

通过试验，发现两个规律：

1.初次上电时，正常概率很低，稳压电源下电后马上再次上电（稳定电源显示电压还未降到0），正常概率很高，下电后等待一段时间，正常概率很低；

2.连接JTAG仿真器后，上电正常的概率要低。（再次上电间隔时间需要更短才能正常）。

查了好几天了，始终没头绪，请大家帮忙分析一下，谢谢

  • 0
    Guru 56631 points

    我觉得应该是读写频率的问题吧

    连上JTAG是不是在RAM中   效率更高  了  

  • 0 回复 mangui zhang
    Prodigy 80 points

    “连上JTAG”仅仅是插上而已，看着似乎更像跟电源有关

  • 0
    TI__Mastermind 23997 points

    F28335 XINTF有一个勘误，可能会导致F28335上电运行不成功，需要外部加硬件看门狗，具体见F28335的勘误手册

    Advisory Memory: Possible Incorrect Operation of XINTF Module After Power Up
    Revision(s) Affected 0, A
    Details The XINTF module may not get reset properly upon power up. When this happens,
    accesses to XINTF addresses may cause the CPU to hang. This issue occurs only upon
    power up. It does not happen for other resets such as a reset initiated by the watchdog
    or an external (warm) reset using the XRS pin.
    Workaround(s) After coming out of reset, software should force a watchdog (WD) reset if WDFLAG = 0
    in the WDCR register. WDFLAG = 0 implies that an external reset occurred, for example,
    a power-on reset. After exiting the WD reset, WDFLAG will be 1. In this case, software
    should clear the WDFLAG bit before continuing normal code execution. This issue
    affects only the XINTF module.