HAL COMP How to Use

group COMP_How_To_Use

How to use the COMP (analog comparator) HAL module driver

HAL COMP driver usage

  • COMP configuration :

    • System configuration (out of HAL COMP driver).

      • RCC to provide COMP kernel clock.

      • GPIO to connect comparator inputs and output to device pins.

      • CPU Cortex NVIC to configure interrupts lines (if COMP usage with interrupt).

    • COMP peripheral configuration.

      • COMP peripheral is structured in subblocks with each a specific scope. HAL COMP follows this structure with a configuration structure and associated function for each subblock.

        • COMP instance subblock:

          • basic configuration (prefix HAL_COMP).

          • output blanking from signal of other peripheral (typically: timer) (optional).

        • COMP multi-instances subblocks:

          • window mode (prefix HAL_COMP_WINDOW): combine multiple COMP instances for voltage comparison to 2 thresholds.

      • COMP instances can belong to a COMP common instance, in this case they can share features (window mode, other shared features, …). HAL COMP driver provides a mechanism to link HAL COMP handles and manage shared features.

    • HAL COMP configuration steps:

      1. Configure system.

      2. Initialize HAL COMP handle using HAL_COMP_Init().

      3. Case of multiple COMP instances used: Link HAL COMP handles using HAL_COMP_WINDOW_SetHandle(). (for more details, refer to function description).

      4. Configure comparator using functions HAL_COMP_[WINDOW]_SetConfig{Features}() and optional features with unitary functions HAL_COMP_[WINDOW]_Set{Features}()

  • COMP operation

    • Activation and deactivation :

      • COMP peripheral requires a specific procedure for activation (internal analog circuitry control, delay for stabilization time). Note: From activation step, COMP internal analog hardware is enabled, inducing current consumption. Therefore, after COMP usage, COMP must be deactivated for power optimization.

    • COMP analog comparison management :

      • Comparisons can be performed using two programming models:

        • Background operation (for system wake up, asynchronous read of comparator output, comparator output on GPIO: using HAL_COMP_[WINDOW]_Start()

        • Interrupt mode: using HAL_COMP_[WINDOW]_StartConv_IT(), HAL_COMP_IRQHandler() and callback functions.

    • HAL COMP operation steps:

      1. Activate and start COMP comparison using functions HAL_COMP_[WINDOW]_Start…(). Optionally, lock comparator using function HAL_COMP_[WINDOW]_Lock(): for safety purpose, comparator configuration frozen until system reset.

      2. Process comparison using HAL_COMP_[WINDOW]_GetOutputLevel(), IRQ handler and callback functions

      3. Deactivate and stop COMP comparison using functions HAL_COMP_[WINDOW]_Stop…() (if not locked).

Callback registration

When the compilation flag USE_HAL_COMP_REGISTER_CALLBACKS is set to 1, functions HAL_COMP_Register…Callback() allow registering following callbacks:

When the compilation flag USE_HAL_COMP_REGISTER_CALLBACKS is set to 0 or not defined, the callback registration feature is not available and all callbacks are set to the corresponding weak functions.