How to read hex values with read function on UART

I need some help with the serial port (UART) read function. I need to read in and display the hex value, but currently I'm reading in the ASCII values.

to send the hex over the UART I use

char data [] = {0xFF};
write(fd, data, sizeof(data));

which does the work well. But I have a problem with the reading in. I want to be able to read hex values and use the read values later.

Currently I'm reading with this function

read(fd, buffer, sizeof(buffer));

But as a result it displays me the ASCII values, I know I need to make some kind of conversion, but I have searched and was unsuccessful of finding how to do it.

Thanks in advance.

Copyright License：
Author:「Anders」,Reproduced under the CC 4.0 BY-SA copyright license with link to original source & disclaimer.
Link to：https://stackoverflow.com/questions/21911401/how-to-read-hex-values-with-read-function-on-uart