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F2812的TRST引脚



您好,有一个F2812的产品,TRST引脚没有接2.2K的下拉电阻,发现其经常在上电后前两分钟不工作。查了芯片手册后接了2.2K的下拉电阻,故障不出现。但我们同事说如果不接2.2K电阻干扰大时是芯片进入了仿真模式,如果不对其上电或复位,芯片不应该在两分钟后又自动工作,是这样吗?怎么解释?谢谢

  • 楼主我认为这件事情其实没有必要进行解释。

    芯片的这一块是黑盒,TI没有文档进行说明。只要按照datasheet的要求对所有引脚进行配置,芯片就能正常运行。

    关于TRST的说明如下:

    JTAG test reset with internal pulldown. TRST,

    when driven high, gives the scan system

    control of the operations of the device. If this

    signal is not connected or driven low, the

    device operates in its functional mode, and the

    test reset signals are ignored.

    NOTE:Do not use pullup resistors on TRST; it

    has an internal pulldown device. TRST is an

    active-high test pin and must be maintained

    low at all times during normal device

    operation. In a low-noise environment, TRST

    may be left floating. In other instances, an

    external pulldown resistor is highly

    recommended. The value of this resistor

    should be based on drive strength of the

    debugger pods applicable to the design. A

    2.2-kΩ resistor generally offers adequate

    protection. Since this is application-specific, it

    is recommended that each target board be

    validated for proper operation of the debugger

    and the application.