参照DEC28335作的，第一次可以连接，烧写不成功，再连接不上，问题如下
Error connecting to the target: (Error -233 @ 0x0) 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. (Emulation package 5.1.232.0)