以前一直能用。试了好几块板子（6713和6747），都报JTAG错误。如下：SC_ERR_PATH_BROKEN <-233>
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 brokenwith a stuck-at-ones or stuck-at-zero fault.