Warning: pointer targets in passing argument 2 of 'HAL_UART_Receive' differ in signedness [-Wpointer-sign]

@MKork.2​ "because of i am new on stm. Why uint8_t ?"

It has nothing specifically to do with STM - this is standard C stuff:

• As the name suggests, uint8_t is unsigned;
• Whether plain char is signed or not is implementation-defined.

You are correct in using char for plain, printable ASCII text - that is what it's for.

However, HAL_UART_Receive() is not restricted to plain text; it handles any arbitrary byte values - hence it uses uint8_t.

You could suppress the warning by casting your char value; eg,

char my_char;
 
HAL_UART_Receive( &huart3, (uint8_t*)&my_char, 1, 10 );

Or you could just make it uint8_t (though you may then get the same warning from C standard string functions - which expect char, not uint8_t)

EDIT

https://en.cppreference.com/w/cpp/types/integer

https://en.wikipedia.org/wiki/C_data_types