Example Summary

Example that uses the ADCBuf driver to make a number of samples and echo them via UART. This example shows how to initialize the ADCBuf driver in continuous mode.

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_ADCBUF_0 - ADCBuf instance.
• CONFIG_ADCBUF_0_CHANNEL_0 - ADC channel 0 of the CONFIG_ADCBUF_0 instance.

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 the ADC channel to a sampling source.
  • For quick testing, connect CONFIG_ADCBUF_0_CHANNEL_0 to GND or 3V3.
  • Note: Undefined values may be returned if the channel is not connected to a sampling source.

Important: Caution should be used when connecting the pins to analog inputs greater than 3VDC.

• 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 will have the following settings:

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

• Run the example.

Example snippet of outputs:

    Starting the ADCBufContinuous example
    Buffer 0 finished:
    Average: 3298384 uV
    Buffer 1 finished:
    Average: 3298384 uV
    Buffer 2 finished:
    Average: 3298384 uV
    ...

• The target will send packages of 50 samples and a header to the serial session. The buffer number and its average microvolt value is displayed on respective new lines.

• Note that many ADCBuf driver implementations use the DMA peripheral in a ping pong buffer configuration. Because of this setting breakpoints while active ADC conversions and DMA transactions are happening will result in unreliable behavior. It is recommended to not set breakpoints in this code example and instead read results via the UART terminal.

Application Design Details

• A single task sets up the UART connection to the serial console and starts a continuous conversion with the ADCBuf driver. After this is completed, the task sleeps forever.

• The ADCBuf driver performs 50 samples at 1000 Hz each.
  • The driver supports higher sampling rates; however, 1000 Hz was chosen for easily interpretable output. The maximum sampling rates are device specific.

• The callback function adcBufCallback is called whenever an ADC buffer is full. The contents of the buffer are first adjusted so that raw results are comparable between devices of the same make. The adjusted values are then converted into microvolts to be human-readable. Lastly, the buffer number and its average microvolt value is displayed via UART.

FreeRTOS:

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