1、错误：

as   -o start.o start.s
start.s: Assembler messages:
start.s:21: 错误： no such instruction: `mrs r0,cpsr'
start.s:22: 错误： no such instruction: `bic r0,r0,'
start.s:23: 错误： no such instruction: `orr r0,r0,'
start.s:24: 错误： no such instruction: `msr cpsr,r0'
start.s:26: 错误： no such instruction: `ldr sp,=0X80200000'
start.s:27: 错误： no such instruction: `b main'
<builtin>: recipe for target 'start.o' failed
make: *** [start.o] Error 1

解决：修改MakeFile文件，两个‘S’保持一样的大小写

        2、错误：

arm-linux-gnueabihf-gcc -Wall -nostdlib -c -O2 -o start.o start.s
 make: *** No rule to make target 'mian.o', needed by 'ledc.bin'。 停止。

检查是否main.o拼写错误

3、arm-linux-gnueabihf-lds -Timx6u.lds -o ledc.elf start.o main.o 
make: arm-linux-gnueabihf-lds：命令未找到
Makefile:13: recipe for target 'ledc.bin' failed
make: *** [ledc.bin] Error 127

修改：链接文件

修改后：