log4Esp - Extendable logging library for ESP8266

log4Esp is a light-wight logging library for ESP8266. As the name suggest it’s inspired by other Apache logging services.

Features

• Support of different log levels (FATAL, ERROR, WARNING, VERBOSE, TRACE)
• Support of printf standards
• Support of formatted strings in flash memory / PROGMEM on ESP8266
• Support of multiple different log destination appenders
• Support of filter options for log events
• Support of adjustable output formats
• Easily extend to your own logging routines

Quick start

    Serial.begin(115200);
    while (!Serial && !Serial.available());      
    
    int d = 392;
    uint16_t u = 7235;
    uint16_t o = 10; // 12 octal
    uint16_t x = 15; // f
    uint16_t X = 15; // F
    float f = 392.65;
    float F = 392.65;
    float e = 3.9265e+2;
    float E = 3.9265e+2;
    float g = 392.65;
    float G = 392.65;
    String s = "sample";
    char c = 'a‘;
    
    // use of global LOG instance with default SerialAppender
    LOG.verbose("int = [%d]", d);                           // [V] int = [392]
    LOG.verbose("uint16_t = [%u]", u);                      // [V] uint16_t = [7235]
    LOG.verbose("octal = [%o]", o);                         // [V] octal = [12]
    LOG.verbose("hexadecimal = [%x]", x);                   // [V] hexadecimal = [f]
    LOG.verbose("hexadecimal uppercase = [%X]", X);         // [V] hexadecimal uppercase = [F]
    LOG.verbose("float (f) = [%f]", f);                     // [V] float (f) = [392.649994]
    LOG.verbose("float (F) = [%F]", F);                     // [V] float (F) = [3.92649994F+02]
    LOG.verbose("float (e) = [%e]", e);                     // [V] float (e) = [3.926500e+02]
    LOG.verbose("float (E) = [%E]", E);                     // [V] float (E) = [3.926500E+02]
    LOG.verbose("float (g) = [%g]", g);                     // [V] float (g) = [392.65]
    LOG.verbose("float (G) = [%G]", G);                     // [V] float (G) = [392.65]
    LOG.verbose("String = [%s]", s.c_str());                // [V] String = [sample]
    LOG.verbose("char = [%c]", c);                          // [V] char = [a]
    LOG.verbose(F("PROGMEM"));                              // [V] PROGMEM
    LOG.verbose("%%");                                      // [V] %
    LOG.verbose("%s(%s:%d)", __func__, __FILE__, __LINE__); // [V] foo(..<path>/foo.ino:123)

Samples

• AdvancedDemo - extends Formatter with Unix timestamp, time date, uptime & free RAM information
• BasicDemo - shows the basic usage
• RollingFileDemo - explains usage of a RollingFileAppender

Dependencies

This library depends solely on ESP8266 core for Arduino

Contribution

Feel encouraged to give feedback or send pull requests on Github.

License

log4Esp is open-source software licensed under the MIT license. For the full copyright and license information, please see the LICENSE file that was distributed with this source code.

Disclaimer

log4Esp is designed for the ESP8266 device only. Other MCU like Arduino, etc. are not supported.