使用CCS调试自己设计的板卡，debug时显示连接不上：
Error connecting to the target: (Error -2131 @ 0x0) Unable to access device register. Reset the device, and retry the operation. If error persists, confirm configuration, power-cycle the board, and/or try more reliable JTAG settings (e.g. lower TCLK). (Emulation package 9.2.0.00002)
我操作的步骤是把launchxl上的TCK,TMS,TDI,TDO四根线接到我设计板卡上对应的引脚上，sop三个引脚全接低电平，请问是什么原因呢？
