DSP 连不上 JTAG， 'SC_ERR_PATH_BROKEN'， 关注EMU1 EMU0

早先设计28335的板子，有EMU0 EMU1两线和DSP上两个引脚对应。

这次做28069的原理图时，看到没有这两个对应引脚，网上查了一下EMU0 EMU1似乎也没什么用途，于是就把2条线省去。

板子焊出来后，发现JTAG连不上芯片。报错如下：

/*********************************************************************分割线****************************************************************************/

[Start: Texas Instruments XDS100v3 USB Emulator_0]


Execute the command:


%ccs_base%/common/uscif/dbgjtag -f %boarddatafile% -rv -o -F inform,logfile=yes -S pathlength -S integrity


[Result]




-----[Print the board config pathname(s)]------------------------------------


C:\Users\ADMINI~1\AppData\Local\TEXASI~1\
    CCS\CCS\0\0\BrdDat\testBoard.dat


-----[Print the reset-command software log-file]-----------------------------


This utility has selected a 100- or 510-class product.
This utility will load the adapter 'jioserdesusbv3.dll'.
The library build date was 'May 21 2014'.
The library build time was '17:19:59'.
The library package version is '5.1.507.0'.
The library component version is '35.34.40.0'.
The controller does not use a programmable FPGA.
The controller has a version number of '4' (0x00000004).
The controller has an insertion length of '0' (0x00000000).
This utility will attempt to reset the controller.
This utility has successfully reset the controller.


-----[Print the reset-command hardware log-file]-----------------------------


The scan-path will be reset by toggling the JTAG TRST signal.
The controller is the FTDI FT2232 with USB interface.
The link from controller to target is direct (without cable).
The software is configured for FTDI FT2232 features.
The controller cannot monitor the value on the EMU[0] pin.
The controller cannot monitor the value on the EMU[1] pin.
The controller cannot control the timing on output pins.
The controller cannot control the timing on input pins.
The scan-path link-delay has been set to exactly '0' (0x0000).


An error occurred while hard opening the controller.


-----[An error has occurred and this utility has aborted]--------------------


This error is generated by TI's USCIF driver or utilities.


The value is '-233' (0xffffff17).
The title is 'SC_ERR_PATH_BROKEN'.


The explanation is:
The JTAG IR and DR scan-paths cannot circulate bits, they may be broken.
An attempt to scan the JTAG scan-path has failed.
The target's JTAG scan-path appears to be broken
with a stuck-at-ones or stuck-at-zero fault.


[End: Texas Instruments XDS100v3 USB Emulator_0]

/*********************************************************************分割线****************************************************************************/

后对比别人的原理图，把EMU0 EMU1各用10K电阻上拉。成功连上芯片。