problem with sprint/printf with freeRTOS on stm32f7 - embedded

Question

Since two days I am trying to make printf\sprintf working in my project...
MCU: STM32F722RETx
I tried to use newLib, heap3, heap4, etc, etc. nothing works. HardFault_Handler is run evry time.
Now I am trying to use simple implementation from this link and still the same problem. I suppose my device has some problem with double numbers, becouse program run HardFault_Handler from this line if (value != value) in _ftoa function.( what is strange because this stm32 support FPU)
Do you guys have any idea? (Now I am using heap_4.c)
My compiller options:
target_compile_options(${PROJ_NAME} PUBLIC
$<$<COMPILE_LANGUAGE:CXX>:
-std=c++14
>
-mcpu=cortex-m7
-mthumb
-mfpu=fpv5-d16
-mfloat-abi=hard
-Wall
-ffunction-sections
-fdata-sections
-O1 -g
-DLV_CONF_INCLUDE_SIMPLE
)
Linker options:
target_link_options(${PROJ_NAME} PUBLIC
${LINKER_OPTION} ${LINKER_SCRIPT}
-mcpu=cortex-m7
-mthumb
-mfloat-abi=hard
-mfpu=fpv5-sp-d16
-specs=nosys.specs
-specs=nano.specs
# -Wl,--wrap,malloc
# -Wl,--wrap,_malloc_r
-u_printf_float
-u_sprintf_float
)
Linker script:
/* Highest address of the user mode stack */
_estack = 0x20040000; /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x200; /* required amount of heap */
_Min_Stack_Size = 0x400; /* required amount of stack */
/* Specify the memory areas */
MEMORY
{
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 256K
FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 512K
}
UPDATE:
I don't think so it is stack problem, I have set configCHECK_FOR_STACK_OVERFLOW to 2, but hook function is never called. I found strange think: This soulution works:
float d = 23.5f;
char buffer[20];
sprintf(buffer, "temp %f", 23.5f);
but this solution not:
float d = 23.5f;
char buffer[20];
sprintf(buffer, "temp %f",d);
No idea why passing variable by copy, generate a HardFault_Handler...

Answer 1

You can implement a hard fault handler that at least will provide you with the SP location to where the issue is occurring. This should provide more insight.
https://www.freertos.org/Debugging-Hard-Faults-On-Cortex-M-Microcontrollers.html
It should let you know if your issue is due to a floating point error within the MCU or if it is due to a branching error possibly caused by some linking problem

Answer 2

I also had error with printf when using FreeRTOS for my SiFive HiFive Rev B.
To solve it, I rewrite _fstat and _write functions to change output function of printf
/*
* Retarget functions for printf()
*/
#include <errno.h>
#include <sys/stat.h>
int _fstat (int file, struct stat * st) {
errno = -ENOSYS;
return -1;
}
int _write (int file, char * ptr, int len) {
extern int uart_putc(int c);
int i;
/* Turn character to capital letter and output to UART port */
for (i = 0; i < len; i++) uart_putc((int)*ptr++);
return 0;
}
And create another uart_putc function for UART0 of SiFive HiFive Rev B hardware:
void uart_putc(int c)
{
#define uart0_txdata (*(volatile uint32_t*)(0x10013000)) // uart0 txdata register
#define UART_TXFULL (1 << 31) // uart0 txdata flag
while ((uart0_txdata & UART_TXFULL) != 0) { }
uart0_txdata = c;
}

Answer 3

The newlib C-runtime library (used in many embedded tool chains) internally uses it's own malloc-family routines. newlib maintains some internal buffers and requires some support for thread-safety:
http://www.nadler.com/embedded/newlibAndFreeRTOS.html
hard fault can caused by unaligned Memory Access:
https://www.keil.com/support/docs/3777.htm