2025 / 03 / 11
e2 studio开发环境下串口printf编译出错问题解决方案
原创:strongerHuang
最近看到有一些网友在讨论关于:瑞萨RA单片机在e2 studio环境下printf编译出错的问题。
这个问题我之前也遇到过,今天就来分享一下我得出的解决办法。
问题点:在 e2 studio 集成开发环境下,使用串口 printf 打印时,会类似出现一个这样的错误:
C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/../../../../arm-none-eabi/bin/ld.exe: C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/thumb/v8-m.main+dp/hard\libg_nano.a(libc_a-closer.o): in function `_close_r':closer.c:(.text._close_r+0xc): undefined reference to `_close'
C:/Renesas/RA/e2studio_-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/../../../../arm-none-eabi/bin/ld.exe: C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/thumb/v8-m.main+dp/hard\libg_nano.a(libc_a-lseekr.o): in function `_lseek_r':lseekr.c:(.text._lseek_r+0x10): undefined reference to `_lseek'
C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/../../../../arm-none-eabi/bin/ld.exe: C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/thumb/v8-m.main+dp/hard\libg_nano.a(libc_a-readr.o): in function `_read_r':readr.c:(.text._read_r+0x10): undefined reference to `_read'
C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/../../../../arm-none-eabi/bin/ld.exe: C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/thumb/v8-m.main+dp/hard\libg_nano.a(libc_a-fstatr.o): in function `_fstat_r':fstatr.c:(.text._fstat_r+0xe): undefined reference to `_fstat'
C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/../../../../arm-none-eabi/bin/ld.exe: C:/Renesas/RA/e2studio_v2024-10_fsp_v5.6.0/toolchains/gcc_arm/13.2.rel1/bin/../lib/gcc/arm-none-eabi/13.2.1/thumb/v8-m.main+dp/hard\libg_nano.a(libc_a-isattyr.o): in function `_isatty_r':isattyr.c:(.text._isatty_r+0xc): undefined reference to `_isatty'
collect2.exe: error: ld returned 1 exit status
make: *** [makefile:96: RA8D1_DEBUG.elf] Error 1
Build Failed. 6 errors, 0 warnings. (took 190ms)

项目 -> C/C++ Project Settings -> C/C++构建 -> 设置 -> GUU Arm Cross C Linker -> Miscellaneous
勾选【Use float with nano printf (-u _ printf float)】这个选项,并清空【Other linker flags】里面的内容。

但是,在 e2 studio V5版本(比如:V5.6.0)环境下,这个解决方法“失效”了,编译还是会出现【错误】。
在同样的路径下,勾选【Do not use syscalls (--specs=nosys.specs)】这个选项,如下图:

这样,确实能解决【编译出错】的问题,也能正常printf打印输出。

这个办法不会错误,也不会警告,也是我在用。那就是在同样的路径下,【Other linker flags】这里添加:

警告这样的配置之后,编译就会:0错误,0警告。

这里的配置,在e2 studio 以前的老版本是默认的,但这后面的版本,这里的配置默认是“空”了,我也搞不懂为啥。
https://community.renesas.com/mcu/ra/f/forum/32521/fsp5-0-0-cannot-print-data-to-uart-by-redirecting-printf
