# Logging and Debugging Messages The logging system is designed to make log messages clearer and improve their uniformity across the project. It makes it easier to see where a log message comes from and what its verbosity is. To use the logging system, include `log.h` in your source file, and use the following macros to print log messages: ```c LOG_DEBUG(TAG, fmt, ...) LOG_INFO(TAG, fmt, ...) LOG_WARN(TAG, fmt, ...) LOG_CRIT(TAG, fmt, ...) LOG_FATAL(TAG, fmt, ...) ``` The same format specifiers as in `printf` can be used. The `TAG` parameter is a string that identifies the source of the log message. It is recommended to use one tag for each source file / module, and to name the tag after the source file / module. See the example below. ## Global Log Level You can control the verbosity of the logging output by setting a global log level in `log.h`. This log level filters out messages with a lower priority. ## Custom Log Levels before you include `log.h`, you can define custom log levels by defining the following macros: ```c // All log messages will be printed #define LOGGER_LEVEL_ALL #include "log.h" ``` ```c // Info and higher priority messages will be printed #define LOGGER_LEVEL_INFO #include "log.h" ``` ```c // Only warnings and errors will be printed #define LOGGER_LEVEL_WARN #include "log.h" ``` ```c // Only log messages with level ERROR will be printed #define LOGGER_LEVEL_CRITICAL #include "log.h" ``` ```c // Only log messages with level ERROR will be printed #define LOGGER_LEVEL_FATAL #include "log.h" ``` ## Colorful Log Messages For improved readability, log messages can be printed in color by defining `LOGGER_USE_COLOR` in `log.h` or before you include `log.h`. \ Default is `0` ## Log Output Format Each log entry is formatted to include the following information: - Log level ([Debug], [Info], [Warn], [Critical], [Fatal]) - Timestamp (in milliseconds since boot) - Tag - The log message For instance, a log entry may look like this: `[Info] (2009) [LTDC]: This is a log message` ## Example ```c #define LOGGER_LEVEL_INFO #include "log.h" // Don't use a define for the tag, as the pointer to the tag is used static const char *TAG = "main"; int main(void) { LOG_DEBUG(TAG, "This message will not be printed"); LOG_INFO(TAG, "This message will be printed"); LOG_WARN(TAG, "This message will be printed"); LOG_CRIT(TAG, "This message will be printed"); LOG_FATAL(TAG, "This message will be printed"); for (int i = 0; i < 3; i++) { LOG_INFO(TAG, "Iteration %d of %d", i, 3); } return 0; } ``` Result: ``` [Info] (2009) [main]: This message will be printed [Warning] (2026) [main]: This message will be printed [CRITICAL] (2033) [main]: This message will be printed [FATAL] (2040) [main]: This message will be printed [Info] (2040) [main]: Iteration 0 of 3 [Info] (2047) [main]: Iteration 1 of 3 [Info] (2054) [main]: Iteration 2 of 3 ```