.. highlight:: cpp Events ====== An event is an asynchronous notification from the MetaWear board represented in the C++ API by the `MblMwEvent `_ struct. Recording Commands ------------------ The board can be programmed to execute MetaWear commands in response to an event firing. An event can be many things such as a data filter (average the accelerometer signal), a disconnect (the board has disconnected from the Bluetooth link), or even a timer (10 seconds have passed). To start recording commands, call `mbl_mw_event_record_commands `_. While in a recording state, all MetaWear functions called will instead be recorded on the board and executed when the event is fired. To stop recording, call `mbl_mw_event_end_record `_. This function is asynchronous and will alert the caller when it is completed via a callback function. If recording events was successful, `MBL_MW_STATUS_OK `_ will be passed into the callback function, otherwise `MBL_MW_STATUS_ERROR_TIMEOUT `_ is used. In this example, when the board is disconnected, the led blinks blue: :: #include "metawear/core/event.h" #include "metawear/core/settings.h" void setup_dc_event(MblMwMetaWearBoard* board) { // Create the LED blue blink pattern MblMwLedPattern pattern; mbl_mw_led_load_preset_pattern(&pattern, MBL_MW_LED_PRESET_BLINK); pattern.repeat_count = 10; // Setup disconnect event to blink the blue led 10x when fired MblMwEvent* dc_event = mbl_mw_settings_get_disconnect_event(board); // Setup the event where the LED blinks blue when the board is disconnected mbl_mw_event_record_commands(dc_event); mbl_mw_led_write_pattern(board, &pattern, MBL_MW_LED_COLOR_BLUE); mbl_mw_led_play(board); mbl_mw_event_end_record(dc_event, [](MblMwEvent* event, int32_t status) -> void { if (!status) { cout << "Error recording commands, status= " << status << endl; } else { cout << "Commands recorded" << endl; } }); } Here is an example where we use the averager data processor to average 4 samples from the accelerometer data. After 4 sample are collected, the averager is reset (otherwise it would continue to accumulate data and average all the data in the processor buffer): :: static auto proc_created = [](MblMwDataProcessor* processor) -> void { printf("averager created\n"); }; // Get accelerometer data auto acc_signal = mbl_mw_acc_get_acceleration_data_signal(board); // Compute running average using the previous 4 samples of accelerometer data avg = mbl_mw_dataprocessor_average_create(acc_signal, 4, proc_created); // Setup event where the average is reset every 4 samples mbl_mw_event_record_commands(avg); mbl_mw_dataprocessor_average_reset(avg); mbl_mw_event_end_record(avg, [](MblMwEvent* event, int32_t status) -> void { if (!status) { cout << "Error recording commands, status= " << status << endl; } else { cout << "Commands recorded" << endl; } }); Here is where we used a timer event to read the temperature of the board: :: // Get the temperature signal tempSignal = MetaWear.mbl_mw_multi_chnl_temp_get_temperature_data_signal(board, 1); // Create a timer that indefinitely fires events every 500ms tempTimer = mbl_mw_timer_create_indefinite(board, 500, 0, timer_created); // Create event based on timer and record as a command mbl_mw_event_record_commands(tempTimer); mbl_mw_datasignal_read(tempSignal); mbl_mw_event_end_record(avg, [](MblMwEvent* event, int32_t status) -> void { if (!status) { cout << "Error recording commands, status= " << status << endl; } else { cout << "Commands recorded" << endl; } });