Example Summary

Example that uses the SYSTIM module to capture timestamps on UART and GPIO events. The example demonstrates how HW events on the device can be captured and how the timestamps for the events can be reported by use of UART. The device operates as a target activated by a specific message that must be input by a user in a terminal connected to a UART session.

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. 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 the UART2 driver was initialized within mainThread().
• CONFIG_GPIO_LED_1 - Indicates execution of the SYSTIM channel 1 capture event ISR.
• CONFIG_UART2_0 - Used to receive/send messages from/to the console of a serial session.
• CONFIG_GPIO_BUTTON_0 - Forces timestamp to be captured and displayed when pressed.

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:

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

Example Usage

• Open a serial session (e.g. PuTTY, etc.) to the appropriate COM port.
  • The COM port can be determined via Device Manager in Windows or via ls /dev/tty* in Linux.

The connection should have the following settings:

    Baud-rate:  115200
    Data bits:       8
    Stop bits:       1
    Parity:       None
    Flow Control: None

• Run the example. CONFIG_GPIO_LED_0 turns ON to indicate driver initialization is complete.

• The target transfers the following message to the serial session: Start listening for UART RX start bit!

• The target will wait for the user to type the following message in the serial session: RX_ID_0

• The target will respond with the following message containing the timestamp (0xNNNNNNNN) for the detection of the UART RX start bit of the message typed by the user: Captured UART RX start bit at timestamp: 0xNNNNNNNN The timestamp is the number of microseconds from target reset.

• The target will then output the following message containing the timestamp (0xNNNNNNNN) for the detection of the UART TX start bit of the previous message transferred by the target: Captured UART TX start bit at timestamp: 0xNNNNNNNN The timestamp is the number of microseconds from target reset.

• The target transfers the following message to the serial session: Start listening for GPIO event!

• When BUTTON_0 is pressed the target will output the following message containing the timestamp (0xNNNNNNNN) for the detection of CONFIG_GPIO_BUTTON_0 activation: Captured GPIO input event at timestamp: 0xNNNNNNNN The timestamp is the number of microseconds from target reset. The example will wait forever for BUTTON_0 to be pressed transferring the described message each time.

Application Design Details

• This example shows how to use the SYSTIM channel 1 capture functionality to register HW events like start of UART RX/TX operations and edges on GPIO pin. The HW events are registered with timestamps holding the number of micro seconds from target reset. The SYSTIM channel 1 can only operate with a 1 usec resolution. Note that the example does not allow the device to enter the Standby power mode as the SYSTIM module is not running during Standby.

FreeRTOS:

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