How to make stm32duino support sprintf under Arduino frame?

kiraversace · November 26, 2020, 5:51am

I have tried add build flags but no effect?
build_flags =
-Wl,–undefined,_printf_float
-DENABLE_HWSERIALLP1
-DPIN_SERIALLP1_RX=PC0
-DPIN_SERIALLP1_TX=PC1

or how to enable it like this

could you help me?

pfeerick · November 26, 2020, 8:50am

Looking at the file boards.txt from which that menu is generated, it looks like you are after:

GenF1.menu.rtlib.nanofp=Newlib Nano + Float Printf
GenF1.menu.rtlib.nanofp.build.flags.ldspecs=--specs=nano.specs -u _printf_float

This gets used in platforms.txt in c.compiler.elf.flags

I just don’t know if you shove it in like build_flags = -Wl,--specs=nano.specs,-u _printf_float or something else… it looks about right given that example you gave for the Arduino Nano/atmega328.

maxgerhardt · November 26, 2020, 8:54am

The docs tell you exactly how to do it.

build_flags = -D PIO_FRAMEWORK_ARDUINO_NANOLIB_FLOAT_PRINTF

in the platformio.ini.

The python builder code will handle it then.

github.com

stm32duino/Arduino_Core_STM32/blob/caa8a28b281d14f91fbdda3744160fb5d40ca419/tools/platformio-build.py#L54-L60


      
          def process_standard_library_configuration(cpp_defines):
              if "PIO_FRAMEWORK_ARDUINO_STANDARD_LIB" in cpp_defines:
                  env["LINKFLAGS"].remove("--specs=nano.specs")
              if "PIO_FRAMEWORK_ARDUINO_NANOLIB_FLOAT_PRINTF" in cpp_defines:
                  env.Append(LINKFLAGS=["-u_printf_float"])
              if "PIO_FRAMEWORK_ARDUINO_NANOLIB_FLOAT_SCANF" in cpp_defines:
                  env.Append(LINKFLAGS=["-u_scanf_float"])

kiraversace · November 27, 2020, 5:50am

thank you for your help