TI中文支持网您好，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
Forrest：
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.
