A while ago, I wrote a library NUM2STR for converting numbers to text in three main formats: decimal, hexadecimal, and binary. I have been using it for several years in another library to print debugging information. The library is designed for the ATtiny85 microcontrollers or similar, written in plain C, and the goal is to work with a minimum amount of memory for code and data.
Library size (approximately):
Program: 1074 bytes (13.1% Full) (.text + .data + .bootloader) Data: 12 bytes (2.3% Full) (.data + .bss + .noinit)
I’ve put all the information on this TinyAVRLib / NUM2STR page.