Example Summary

Demonstrates how to use SPI driver in peripheral mode to communicate with another SimpleLink device. To run this example successfully, another SimpleLink device running the spicontroller example is required.

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_SPI_CONTROLLER - SPI peripheral assigned as a controller.
• CONFIG_SPI_CONTROLLER_READY - GPIO managed by controller to notify the peripheral CONFIG_SPI_CONTROLLER has been opened.
• CONFIG_SPI_PERIPHERAL_READY - GPIO to notify the controller the peripheral is ready for a transfer.
• CONFIG_GPIO_LED_0 - Indicator LED.
• CONFIG_GPIO_LED_1 - Indicator LED.

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>

Before running the example the following pins must be connected between controller & peripheral devices.

SPI Controller LaunchPad	SPI Peripheral LaunchPad
CONFIG_SPI_CONTROLLER_CLK	CONFIG_SPI_PERIPHERAL_CLK
CONFIG_SPI_CONTROLLER_PICO	CONFIG_SPI_PERIPHERAL_PICO
CONFIG_SPI_CONTROLLER_POCI	CONFIG_SPI_PERIPHERAL_POCI
CONFIG_SPI_CONTROLLER_CSN	CONFIG_SPI_PERIPHERAL_CS
CONFIG_SPI_CONTROLLER_READY	CONFIG_SPI_CONTROLLER_READY
CONFIG_SPI_PERIPHERAL_READY	CONFIG_SPI_PERIPHERAL_READY

• The SPI can be used in 4-pin or 3-pin modes (chip select is optional). When running this example SPI peripherals on both SimpleLink devices must align on chip select use. Users must verify before running the example.

• Although not in the table above, a ground jumper must also be connected between both boards.

Example Usage

• Example output is generated through use of Display driver APIs. Refer to the Display driver documentation.

• 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. CONFIG_GPIO_LED_0 turns ON to show the example is running.

• Once the controller is running, controller and peripheral devices will exchange messages in a loop. While the SPI transaction is taking place, CONFIG_GPIO_LED1 will toggle on/off indicating transfers are occurring. After a transfer is complete, the messages are printed via UART. The loop is repeated MAX_LOOP times.

Messages should appear as follows:

    Starting the SPI peripheral example
    This example requires external wires to be connected to the header pins. Please see the Board.html for details.

    Peripheral SPI initialized

    Peripheral received: Hello from controller, msg#: 0
    Peripheral received: Hello from controller, msg#: 1
    Peripheral received: Hello from controller, msg#: 2
    Peripheral received: Hello from controller, msg#: 3
    Peripheral received: Hello from controller, msg#: 4
    Peripheral received: Hello from controller, msg#: 5
    Peripheral received: Hello from controller, msg#: 6
    Peripheral received: Hello from controller, msg#: 7
    Peripheral received: Hello from controller, msg#: 8
    Peripheral received: Hello from controller, msg#: 9

    Done

Application Design Details

This application uses a single thread:

peripheralThread - waits for controller to open CONFIG_SPI_CONTROLLER, opens CONFIG_SPI_PERIPHERAL, creates the peripheral message and prepares a transfer. The CONFIG_SPI_PERIPHERAL_READY pin is pulled low to notify the controller it is ready. Once the transfer complete, peripheral pulls CONFIG_SPI_PERIPHERAL_READY high, prepares the next transaction and pulls CONFIG_SPI_PERIPHERAL_READY low again. A total of MAX_LOOP SPI transactions are performed in this manner.

The peripheralThread performs the following actions:

1. Before performing transfers, we must make sure both, spicontroller & spiperipheral applications are synchronized with each other. The peripheral will set CONFIG_SPI_PERIPHERAL_READY to 1 to notify the controller it is ready to synchronize. The peripheral will then wait for the controller to pull CONFIG_SPI_CONTROLLER_READY high in acknowledgment.

2. Waits until controller has opened CONFIG_SPI_CONTROLLER. Controller will pull CONFIG_SPI_CONTROLLER_READY low once it has opened its SPI peripheral.

3. Opens CONFIG_SPI_PERIPHERAL in callback mode.

4. Creates a SPI transaction structure and sets txBuffer to Hello from peripheral, msg# n, where n is the iteration number.

5. Toggles CONFIG_GPIO_LED_1.

6. Performs the SPI transfer in callback mode. If the transfer is successful, CONFIG_SPI_PERIPHERAL_READY is pulled low to notify the controller the peripheral is ready for a transfer and the peripheral waits until the transfer has completed. Otherwise, an error message is printed to the UART.

7. Once the transfer is completed, CONFIG_SPI_PERIPHERAL_READY is pulled high to notify controller peripheral is not ready for another transfer.

8. Repeats from step 4 for MAX_LOOP iterations.

9. Closes the SPI driver object and terminates execution.

FreeRTOS:

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