本人使用RVSTAR MCU板子，从官网下载的例程可以打印helloworld，可以正常下载程序，当我将其改成点亮LED时，下载程序出现下面这种错误：
Info : clock speed 5000 kHz
Error: JTAG scan chain interrogation failed: all ones
Error: Check JTAG interface, timings, target power, etc.
Error: Trying to use configured scan chain anyway…
Error: riscv.cpu: IR capture error; saw 0x1f not 0x01
Warn : Bypassing JTAG setup events due to errors
Error: [riscv.cpu] Unsupported DTM version: 15
Warn : target riscv.cpu examination failed
Error: [riscv.cpu] Unsupported DTM version: 15
Error: [riscv.cpu] Unsupported DTM version: 15
Info : starting gdb server for riscv.cpu on 3333
Info : Listening on port 3333 for gdb connections
Error: Target not examined yet
Error: [riscv.cpu] Unsupported DTM version: 15
请问怎么解决？望各位大神解答