刚刚还下载正常突然就不行了，同样的程序下载进别的板子就可以，提示如下：

jlink的信息是这样的：
SEGGER J-Link Commander V4.90e ('?' for help)
Compiled Sep  8 2014 18:46:42
DLL version V4.91b, compiled Sep 15 2014 09:17:56
Firmware: J-Link ARM V8 compiled Jul 17 2014 12:31:18
Hardware: V8.00
S/N: 1631096674
Feature(s): RDI,FlashDL,FlashBP,JFlash,GDBFULL
VTarget = 0.731V
No devices found on JTAG chain. Trying to find device on SWD.
No device found on SWD.
Did not find any core.
Failed to identify target. Trying again with slow (4 kHz) speed.
No devices found on JTAG chain. Trying to find device on SWD.
No device found on SWD.
Did not find any core.
No device found at all. Selecting JTAG as default target interface.

SWD锁了？把BOOT0置高，再试下

现在好了，是因为我的排线不知道哪里坏了，谢谢解答