Overview

As the name would imply, device managers are responsible for "managing" devices used by the system. Each device type (input, output, etc.) has its own type-specific device manager.

A device manager serves two primary purposes:

• Initializing and starting each device registered to that manager
• Sending data to and receiving data from each device registered to that manager

This section will avoid low-level implementation details of the device managers and instead focus on the device manager APIs and the startup flow for the device managers. The device managers themselves are provided as a library binary file to, in part, help abstract the underlying implementation details and encourage developers to focus on the HAL devices being managed instead.

info

The device managers themselves are provided as a library binary file in the framework folder, while the APIs for each manager can be found in the framework/inc folder.

Initialization Flow

Before a device manager can properly manage devices, it must follow a specific startup process. The startup process for device managers is summarized as follows:

1. Initialize managers
2. Register each device to their respective manager
3. Start managers

This process is clearly demonstrated in the main function found in source/main.cpp

source/main.cpp

/*
 * @brief   Application entry point.
 */
int main(void)
{
    /* Init board hardware. */
    APP_BoardInit();
    LOGD("[MAIN]:Started");
    /* init the framework*/
    APP_InitFramework();

    /* register the hal devices*/
    APP_RegisterHalDevices();

    /* start the framework*/
    APP_StartFramework();

    // start
    vTaskStartScheduler();

    while (1)
    {
        LOGD("#");
    }

    return 0;
}

As part of a manager's start routine, the manager will call the init and start functions of each of its registered devices.

note

In general, developers should only be concerned with adding/removing devices from the APP_RegisterHalDevices() function as the Init and Start functions for each manager is already called by default inside the APP_InitFramework() and APP_StartFramework() functions in main().