How to convert HEX to Float Mid-Little Endian (CDAB) in STM32CubeIDE?

data [3] = 0x6A; -Very similar to the uint8_t data [x] array. In this case, "0x6A" is a symbolic representation of the stored value in HEX format. In this case, it is enough to reverse the byte order, align the result at the address.

float ss(uint8_t* data){
union {float out; uint8_t in[4];}sse;
sse.in[3]=*(data++);sse.in[2]=*(data++);
sse.in[1]=*(data++);sse.in[0]=*(data++);
return sse.out;
}

However, if the data is written to a file with the NEX extension, then parsing is required. There, 2 bytes of character data in char format are spent for one byte of data, + additional information for each data line. And yet, there are several dozen "HEX" data storage / transmission formats. You need to decide what you are dealing with. The easiest way to do this is by opening the file in binary representation, because editors and IDEs automatically hide the file markup.