AvrArdLogging

About

A simple logging library for Arduino and other AVR based projects that uses no code space if no log level is defined. Automatically stores log strings in PROGMEM.

Uses the Serial class on Arduino platforms and very simple, blocking USART access otherwise (room for improvement here).

Uses the AVR printf() libraries instead of Stream.write for portability and better readability of code using logging. Also, repeated use of Serial.print would also inflate code size quite a bit (same with streaming (<<) or cascadable print libraries), so printf() seemed more suitable for me - especially with today's memory sizes on AVR chips / Arduino boards.
For the printf() libraries to be usable with Serial/USART, stdout is redirected, so one can also just do a printf() anywhere in code to output to Serial/USART.

Homepage: https://github.com/felixstorm/AvrArdLogging

Usage

Add a single line with only LOG_GLOBALS on a global level in any one source file and initialize logging somewhere in code with LOG_INIT(baudRate); before you use it.

Define the desired log level in a global include file or individually in every source file before including this file:

#define LOG_LEVEL 5
#include "AvrArdLogging.h"

Log Levels are 0-5:

0 or undefined => off
1 => errors only (LOG_ERR)
2 => plus warnings (LOG_WARN)
3 => plus infos (LOG),
4 => plus verbose (LOG_VERB)
5 => plus debug (LOG_DBG)

Alternatively the log level symbol may be defined globally as a command line compiler option (e.g. in AtmelStudio 6 in Project Properties - Toolchain - AVR/GNU C and/or C++ Compiler - Symbols as LOG_LEVEL=5).

To log, use LOG_ERR(fmt, ...), LOG_WARN(fmt, ...), LOG(fmt, ...), LOG_VERB(fmt, ...), LOG_DBG(fmt, ...) in your code (syntax like printf(), CRLF will be appended automatically):

LOG_ERR("Error connecting to server, http status was %d", httpStatus);

Also, there are LOGB_ERR(fmt, ...), LOGC_ERR(fmt, ...), LOGE_ERR(fmt, ...) to _B_egin, _C_ontinue and _E_nd a log line (for the other levels respectively):

LOGB_VERB("Waiting for sensor readings");
pseudo code loop {
	LOGC_VERB(" - received %d", reading);
}
LOGE_VERB(" - done.");

Feel free to adjust my log event layouts to your taste ;-)

printf() Flavors

The AVR printf() libraries come in three flavors/code sizes: minimal (very basic integer and string conversion facilities only), default and with floating point support. For details and respective supported printf() format string options, see:
http://www.nongnu.org/avr-libc/user-manual/group__avr__stdio.html#gaa3b98c0d17b35642c0f3e4649092b9f1

• Without any specific linker options, the default printf() library will be used.

• To only use the minimal version, undef vfprintf and include the printf_min library in the linker options:
  -Wl,-u,vfprintf -lprintf_min
  in AtmelStudio: in Project Properties - Toolchain - AVR/GNU Linker - in General, check "Use vprintf library" and in Libraries add printf_min)

• To enable floating point support, also undef vfprintf and include printf_flt and m (math) libraries:
  -Wl,-u,vfprintf -lprintf_flt -lm
  see above for AtmelStudio (Arduino core library must be in library list before m, otherwise floating point usage will throw linker errors)

Resources, My Inspirations etc.

http://www.nongnu.org/avr-libc/user-manual/group__avr__stdio.html
http://playground.arduino.cc/Main/Printf
http://code.google.com/p/arduino-library-dbg
http://www.appelsiini.net/2011/simple-usart-with-avr-libc
http://homepage.hispeed.ch/peterfleury/group__pfleury__uart.html

License: GPL

http://www.gnu.org/licenses/gpl.html