使用Arduino Due调用FFT库函数时编译器报错

最近在用Arduino Due开发板调用库函数进行FFT运算，我选择的IDE为Arduino 1.8.9，安装的软件包为Arduino SAM boards（32-bits ARM Cortex-M3）by Arduino 版本1.6.12，但编译器始终不通过，错误如下：

Arduino:1.8.9 (Windows 10), 开发板："Arduino Due (Programming Port)"

构建选项已变更，全部重新构建
In file included from F:ArduinoEITEIT.ino:3:0:

C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12system/CMSIS/CMSIS/Include/arm_math.h:283:0: warning: "PI" redefined [enabled by default]

 #define PI     3.14159265358979f

 ^

In file included from C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12coresarduino/Arduino.h:44:0,

                 from sketchEIT.ino.cpp:1:

C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12coresarduino/wiring_constants.h:36:0: note: this is the location of the previous definition

 #define PI 3.1415926535897932384626433832795

 ^

sketchEIT.ino.cpp.o: In function `Impedance_Readout(double):

F:ArduinoEIT/EIT.ino:288: undefined reference to `arm_fill_f32

F:ArduinoEIT/EIT.ino:301: undefined reference to `arm_cfft_radix4_init_f32

F:ArduinoEIT/EIT.ino:303: undefined reference to `arm_cfft_radix4_f32

F:ArduinoEIT/EIT.ino:304: undefined reference to `arm_copy_f32

F:ArduinoEIT/EIT.ino:305: undefined reference to `arm_cmplx_mag_f32

collect2.exe: error: ld returned 1 exit status

exit status 1
为开发板 Arduino Due (Programming Port) 编译时出错。

在文件 -> 首选项开启
“编译过程中显示详细输出”选项
这份报告会包含更多信息。

编译器主要给出两个错误：

1. PI重定义了。
2. 库函数没法调用。

解决方法如下：

针对错误1，我把

C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12coresarduino

路径下的wiring_constants.h文件的第36行：

#define PI 3.1415926535897932384626433832795

注释掉。

针对错误2，我参考了 这个链接对应的帖子，具体修改如下：

1. 把目录： C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12systemCMSISCMSISLibGCC 下的libarm_cortexM3l_math.a文件复制到了目录： C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12variantsarduino_due_x 下
2. 打开目录： C:UsersLenovoAppDataLocalArduino15packagesarduinohardwaresam1.6.12 下的platform.txt文档，把第81行： recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" -mcpu={build.mcu} -mthumb {compiler.c.elf.flags} "-T{build.variant.path}/{build.ldscript}" "-Wl,-Map,{build.path}/{build.project_name}.map" {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" "-L{build.path}" -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--entry=Reset_Handler -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--start-group {compiler.combine.flags} {object_files} "{build.variant.path}/{build.variant_system_lib}" "{build.path}/{archive_file}" -Wl,--end-group -lm -lgcc 修改为：

recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" -mcpu={build.mcu} -mthumb {compiler.c.elf.flags} "-T{build.variant.path}/{build.ldscript}" "-Wl,-Map,{build.path}/{build.project_name}.map" {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" "-L{build.path}" -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--entry=Reset_Handler -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--start-group {compiler.combine.flags} {object_files} "{build.variant.path}/{build.variant_system_lib}" "{build.variant.path}/libarm_cortexM3l_math.a" "{build.path}/{archive_file}" -Wl,--end-group -lm -lgcc

在原来那行代码接近末尾的位置加上了"{build.variant.path}/libarm_cortexM3l_math.a"的编译选项。 解决了以上两个编译错误，代码就编译成功了，可以调用FFT函数库了~对了，要调用FFT对应的库函数，别忘了加上宏定义：

#define ARM_MATH_CM3
#include "arm_math.h"