Example Summary

This example uses the Comparator driver to detect a voltage threshold and toggle an LED.

Peripherals & Pin Assignments

When this project is built, the SysConfig tool will generate the TI-Driver configurations into the ti_drivers_config.c and ti_drivers_config.h files. Information on pins and resources used is present in both generated files. Note for this example the positive terminal is used as a reference. And the input voltage is on the negative terminal. The negative terminal is determined by the comparator module ID. Additionally, the System Configuration file (*.syscfg) present in the project may be opened with SysConfig’s graphical user interface to determine pins and resources used.

• CONFIG_GPIO_LED_0 - Indicates that the driver was initialized within mainThread().
• CONFIG_GPIO_BUTTON_0 - Configure LaunchPad Button BTN-1 in mainThread() to serve as input trigger to the comparator.
• CONFIG_COMPARATOR_0 - Defines the comparator peripheral, Positive Terminal, Negative Terminal, and Output Pin.

BoosterPacks, Board Resources & Jumper Settings

For board specific jumper settings, resources and BoosterPack modifications, refer to the Board.html file.

If you’re using an IDE such as Code Composer Studio (CCS) or IAR, please refer to Board.html in your project directory for resources used and board-specific jumper settings.

The Board.html can also be found in your SDK installation:

<SDK_INSTALL_DIR>/source/ti/boards/<BOARD>

Example Usage

• Connect a jumper between LaunchPad Button BTN-1 and Comparator Positive Input (A1).

• Run the example.

• Press BTN-1 (Left Button on the launch pad) to trigger a voltage level change. The example has been set up to toggle LED0, the red LED on the launchpad, upon detection of a falling edge.

Application Design Details

• This example shows how to initialize the Comparator driver, set up comparator interrupts, and read the current comparator output.

• The comparator’s internal voltage reference is set to be half the value of VDDs. In this example, the user-supplied input voltage is connected to the positive input of the comparator, and the internal voltage reference is connected to the negative comparator terminal.

• The comparator generates an interrupt when a rising or falling edge, which also crosses the internal voltage reference threshold, occurs on the comparator’s Positive Input Pin.

• The comparator interrupt reads the current output level of the comparator’s Positive Input Pin and toggles the CONFIG_GPIO_LED0 upon detection of a falling edge followed by a low voltage level measured by the comparator.

FreeRTOS:

• Please view the FreeRTOSConfig.h header file for example configuration information.