Error:Flash Download Failed-"Cortex-M3"出现一般情况：
SWD模式下，Debug菜单中，Reset菜单选项（Autodetect/HWreset/sysresetReq/Vectreset）默认是AutoDetect，改成SysResetReq即可。
Reset — HW RESET performs a hardware reset by asserting the hardware reset (HW RESET) signal.
Reset — SYSRESETREQ performs a software reset by setting the SYSRESETREQ bit. The Cortex-M core and on-chip peripherals are reset.
Reset — VECTRESET performs a software reset by setting the VECTRESET bit. Only the Cortex-M core is reset. The on-chip peripherals are not affected. For some Cortex-M devices, VECTRESET is the only way to reset the core. VECTRESET is not supported on Cortex-M0 and Cortex-M1 cores.
Reset — Autodetect selects one of the above reset methods based on the target device. The SYSRESETREQ method is used if an unknown device is detected.
src\user\main.c(9): warning: #1-D: last line of file ends without a newline
MAIN（）函数的“}”没有回车，在“}”后面回车几行，如果这时编译还有报错，那就是你回车后的最后一行里有空格，即相当于用了Tab键的效果，把那几个空格删除即可。
error: L6235E: More than one section matches selector - cannot all be FIRST/LAST
遇到这个问题时候，查看 中的文件属性，修改文件属性即可。