Table of Contents

Example Summary

Example that uses the UART driver to echo back to the console. It also demonstrates System Analyzer usage via a stop-mode logger.

Peripherals Exercised

• Board_LED0 - Indicates that the board was initialized within main()
• Board_UART0 - Used to echo characters from host serial session

Resources & Jumper Settings

Please refer to the development board’s specific Settings and Resources section in the Getting Started Guide. For convenience, a short summary is also shown below.

Fields left blank have no specific settings for this example.

Example Usage

• Run the example. Board_LED0 turns ON to indicate TI-RTOS driver initialization is complete.

• When the application is running, open a serial session (e.g. HyperTerminal, 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:    9600
    Data bits:       8
    Stop bits:       1
    Parity:       None
    Flow Control: None

• The target echoes back any character that is typed in the serial session.

• If the serial session is started before the target completes initialization, the following is displayed: Echoing characters:

• This example also demonstrates System Analyzer in CCS. This is accomplished via stop-mode reading of the logs on the target. Halt the target and open System Analyzer as described in the TI-RTOS User Guide’s Viewing the Logs.

The Live Session should have records like the following

   - "LS_cpuLoad: 0%"
   - "Wrote character 0xa"

Application Design Details

• This example shows how to initialize the UART driver in blocking read and write mode with no data processing and echo characters back to a console.

• A single task, echo, reads a character from Board_UART0 and writes it back.

• This example uses the default StopMode logger with LoggingSetup. Log records are stored in internal buffers. They are read by System Analyzer when the target is halted. If the target is not halted and the buffers are full, the old records are over-written.

• To help fill up the logs, the kernel is configured to generate Log records via the following from the .cfg file BIOS.logsEnabled = true;

• Additionally, the drivers instrumentation is turned on to demonstrate logging in the drivers. For this example, UART logs will show up in the Main logger. TIRTOS.libType = TIRTOS.LibType_Instrumented;

Most of the other examples do not use instrumented libraries to improve performance and minimize footprint.

• Using the UART DMA Driver

The CC3200 and TivaC platforms have DMA support for the UART driver. For these platforms, the uartecho example can be built with either the UART driver with DMA support, or the non-DMA UART driver. The default configuration for this example is to use the non-DMA UART driver. Since only one character at a time is sent to the UART, this example is not an efficient use of the DMA, but it still serves to illustrate use of the UART DMA driver. To use the DMA version of the UART driver, build this example with the compile flag:

--define=TI_DRIVERS_UART_DMA=1

The .c file includes either the UART driver with DMA support or the non-DMA UART driver, based on this compile flag.

For IAR users using any SensorTag(STK) Board, the XDS110 debugger must be selected with the 4-wire JTAG connection within your projects’ debugger configuration.

References

• For GNU and IAR users, please read the following website for details about enabling semi-hosting in order to view console output.