es-printf is an implementation of the standard C printf function targetted at small embedded systems with very restricted code and data space. It provides several advantages over the standard library function:

1. There are many fine-grained customisations which allow you to trim the size to absolute minimum so it will fit in limited code space. You can elect to have only hexadecimal output, full floating point support and any number of options in between. The smallest configuration typically uses less than 200 bytes of code space.

2. It does not use any static buffers so it is thread-safe and can safely be used within interrupts and in an RTOS environment.

3. You provide your own output function which can be to a serial port or to anything else convenient.

4. Because the source code is available it is easy to extend the formatter to provide custom specifiers for your particular needs.

Full documentation is provided in es-printf.html