Additional attributes

As described in previous sections, certain log message attributes, such as a timestamp, are automatically added to all generated messages. The library also defines some attributes that can be used for application-specific needs:

  • code : arbitrary integer value (e.g. error code)
  • details : description string (e.g. error message)
// EXAMPLE - specifying additional attributes

SerialLogHandler logHandler;

int connect() {
    return ECONNREFUSED; // Return an error

void setup() {
    Log.info("Connecting to server");
    int error = connect();
    if (error) {
        // Get error message string
        const char *message = strerror(error);
        // Log message with additional attributes
        Log.code(error).details(message).error("Connection error");

void loop() {

The example application specifies code and details attributes for the error message, generating the following logging output:

0000000084 [app] INFO: Connecting to server
0000000087 [app] ERROR: Connection error [code = 111, details = Connection refused]