The type_char conversion type character is used to specify the way the function argument will be treated.
The following conversion type characters are supported:
'i' - the function argument is a signed decimal integer;
'd' - the function argument is a signed decimal integer;
'u' - the function argument is an unsigned decimal integer;
'e' - the function argument is a float, that will be outputted using the [-]d.dddddd e[-]dd format
'E' - the function argument is a float, that will be outputted using the [-]d.dddddd E[-]dd format
'f' - the function argument is a float, that will be outputted using the [-]ddd.dddddd format
'x' - the function argument is an unsigned hexadecimal integer, that will be outputted with lowercase characters;
'X' - the function argument is an unsigned hexadecimal integer, that will be outputted with with uppercase characters;
'c' - the function argument is a single character;
's' - the function argument is a pointer to a null terminated char string located in SRAM;

'p' - the function argument is a pointer to a null terminated char string located in FLASH;
'%' - the '%' character will be outputted.