Logger

Loggers record data from a data signal and are represented by the MblMwDataLogger struct. Create an MblMwDataLogger object by calling mbl_mw_datasignal_log with the data signal you want to log. If successful, the callback function will be executed with a MblMwDataLogger* pointer and a null pointer if it failed.

#include "metawear/core/datasignal.h"
#include "metawear/core/logging_fwd.h"
#include "metawear/sensor/multichanneltemperature.h"

auto temp_signal = mbl_mw_multi_chnl_temp_get_temperature_data_signal(board, 0);
mbl_mw_datasignal_log(temp_signal, nullptr, [](void* context, MblMwDataLogger* logger) -> void {
    if (logger != nullptr) {
        printf("logger ready\n");
    } else {
        printf("Failed to create the logger\n");
    }
});

MblMwDataLogger objects only interact with the specific data signal, they do not control the logging features. Logging control functions are detailed in the Logging section.

ID

MblMwDataLogger objects are identified by a numerical id; you can retrieve the id by calling mbl_mw_logger_get_id. The id is used to retrieve existing loggers from the API with the mbl_mw_logger_lookup_id function.

Handling Data

Like a data signal, you can subscribe to an MblMwDataLogger to process the downloaded data. Call mbl_mw_logger_subscribe to attach a callback function to the MblMwDataLogger which handles all received data.

void logger_subscribe(MblMwDataLogger* temp_logger) {
    mbl_mw_logger_subscribe(temp_logger, context, [](void* context, const MblMwData* data) -> void {
        printf("temperature= %.3fC\n", *((float*) data->value));
    });
}

Removal

When you no longer want to log the values from a data signal, call mbl_mw_logger_remove to remove the logger.