SimpleLink MCU SDK User's Guide

Introduction to SimpleLink™ MCU SDK

The SimpleLink™ MCU Software Development Kit (SDK) is a set of software development tools that enables engineers to develop applications on a range of micro-controller families from Texas Instruments. This powerful software toolkit provides a cohesive and consistent software experience by packaging essential software components and easy-to-use examples in one easy-to-use software package.

If you have not already installed the SDK and performed the initial setup steps, see the Quickstart Guide.

Documentation and Support

Links to documentation for the SDK and its components are provided in the Documentation Overview.

This SDK is supported on the TI E2E Community.

SDK Components

The SDK components are used together to build applications. The SDK components relate to each other as shown in the following diagram.

Starting from the bottom of this architecture diagram, the components are as follows:

• Hardware: The TI SimpleLink family:
  • MSP432: Low-power MCUs built around an ARM Cortex M4 core and optimized for Internet-of-Things sensor nodes.
  • CC32xx: ARM Cortex M4-based MCUs with integrated WiFi and security features.
  • CC26xx/CC13xx: Low-power wireless ARM Cortex M3-based MCUs for high performance RF applications. These devices support a range of wireless standards.
• Hardware Abstraction Layer (HAL): C functions that abstract writes to hardware registers. This is the layer the drivers and OS kernel use to access hardware features.
• OS/Kernel: The kernel provides services such as timing and scheduling of tasks. All TI SimpleLink SDKs come with the TI-RTOS Kernel. Some SDKs also support alternative RTOS kernels (such as FreeRTOS).
  • The Driver Porting Layer (DPL) abstracts driver interfaces. Drivers use RTOS features such as clocks, interrupts, mutexes, and semaphores. By abstracting this functionality, applications that use TI Drivers are not dependent on the TI-RTOS Kernel and can instead use the FreeRTOS kernel.
  • The POSIX layer abstracts the RTOS kernel functionality used by applications. The POSIX layer allows examples and user applications to be easily ported to use a different kernel. Using this layer is optional. (See "Choosing Whether to Use POSIX.")
• TI Drivers API: Exposes functionality of the hardware-specific drivers in the same way across all TI SimpleLink devices. Though the hardware implementation of the UART may be different on different chipsets, the TI Drivers API used to access its common functionality is the same.
• Middleware: Add functionality on top of drivers. Communications stacks and graphics libraries are examples of middleware.
• Examples: The SDK provides a wide range of examples. Their purpose is to make it easy to start writing applications. Each example comes with its own documentation and project files. Examples are provided that use the supported RTOS kernels. For certain SDKs, examples that do not use an RTOS are also provided.

Directory Structure

The SDK is installed in /ti or c:\ti by default. This is also the installation location for any plug-ins that are installed alongside the SDK. This is the top-level directory structure of the SDK installation:

• The "docs" directory contains all the documentation files for the various SDK components. The Documentation Overview links to these documents.
• The "examples" directory contains a number of example applications for each supported board.
• The "kernel" directory contains the files required to use the TI-RTOS Kernel and the FreeRTOS kernel. The kernels implement the DPL and POSIX layers, which allow an SDK application to switch between the supported kernels.
• The "source" directory contains source code, libraries, and linker files used when building applications. This includes files for drivers, boards, devices, middleware, and more. For example, the source code for all the TI Drivers is provided here. See the following figure for more about the contents of this directory tree.

Since the same directory structure is used across the different SDKs in the TI SimpleLink family, it is possible to move application code between the different devices without making significant changes to the file structure or include paths.

The following figure shows the contents of the "source" directory. Notice the key in the lower-left, which shows the colors used to indicate target-specific packages within the SDK.

The following figure similarly shows more detail about the contents of the "examples" directory using the same color code.

Tools and Utilities Not Included

The SDK does not contain an IDE or code generation tools such as a compiler and linker. You should have one of the supported code generation tool suites available. The supported suites are Code Composer Studio with TI's Code Generation Tools, IAR Workbench with its compilers, and the GNU Compiler Collection (gcc).

The SDK does not install FreeRTOS. You can download the FreeRTOS source files via the FreeRTOS website. The SDK does install the Driver Porting Layer (DPL) and POSIX abstractions to allow FreeRTOS to be used with the other SDK components.

The SDK does install XDCtools, which includes configuration tools for the TI-RTOS Kernel. The XDCtools component contains the underlying tools and modules used by TI-RTOS and its kernel. When you install the SDK, XDCtools is installed in a parallel directory at the same level as the SDK's installation directory.

Some versions of the SDK also offer functionality-specific tools, such as the BTool for interfacing with the TI Bluetooth Low Energy (BLE) stack from a PC.

Understanding a SimpleLink MCU SDK Application

The SimpleLink MCU SDK provides an example called demos\portable that serves as an introduction to creating your own applications using the SDK. The example uses the UART and I2C drivers and low-power states. It illustrates multi-tasking, I/O drivers, and low-power states. The code uses POSIX so that it is easy to run the example using either the TI-RTOS Kernel or the FreeRTOS kernel.

The application has the following functionality.

• Initializes the UART driver in blocking read and write mode.
• The consoleThread thread provides a simple console. When the UART is closed, the device can go into a lower-power state.
• The temperatureThread thread reads the temperature from a peripheral device via the I2C driver.

The "portable" example is located in the <SDK_INSTALL_DIR>\examples\rtos\<board>\demos\portable directory. It is available for all supported boards, RTOS kernels, toolchains, and IDEs.

Importing, Building, and Running the Example

Import the example as described in the Quickstart Guide. Separate instructions are provided there for the Code Composer Studio (CCS) IDE, IAR Embedded Workbench, makefiles using the GCC compiler, and other supported development environments. Follow the instructions in the "Execute your First Application" section of the Quickstart Guide for your development environment, but choose the "portable" example for your board, RTOS (TI-RTOS or FreeRTOS), and compiler.

Build the "portable" example as described in the same section of the Quickstart Guide.

A README.html file is included with the example files you imported. View this file and follow the instructions in the "Example Usage" section to run the example.

For boards other than CC3220, you'll need the Sensors BoosterPack, which contains a TMP007 temperature sensor.

For CC3220 boards using CCS, let the device “Free Run” instead of "Run."

Understanding the Example

This section examines the "portable" example's code to understand how it was created.

To see how the example supports multiple IDEs and RTOS kernels, it is best to look at the example files in the SDK installation. The process of importing an example removes files used to support other IDEs and RTOS kernels than the one you are using.

Go to your <SDK_INSTALL_DIR>\examples\rtos\<board>\demos\portable directory.

The example contains the following source files:

• main_tirtos.c and main_freertos.c: These files contain the main() function. They are located in subdirectories and use POSIX (pthread) calls to initialize drivers and create the threads that will run the consoleThread and the temperatureThread threads.
• console.c: This file contains the function run by the consoleThread thread along with the callback function for the GPIO interrupt run when the board BUTTON1 is pressed.
• temperature.c: This file contains the function run by the temperatureThread thread.
• <board>.c and <board>.h (where <board> is the name of your board): These file set up board-specific items, such as attribute structures for the various TI Drivers. For example, for the UART driver, properties such as the clock source and pins used are configured.
• Board.h: Maps board-specific constants to board-independent constants that can be used by the application so that the application code is portable.

The following sections examine these parts of the application in more detail. Open the code files as you read these sections to better understand how an application uses the SDK.

main_tirtos.c and main_freertos.c

The two versions of the main() function are mostly identical. Because POSIX Pthreads are used instead of direct calls to kernel APIs, only minor differences are needed to run the TI-RTOS Kernel or the FreeRTOS kernel.

Header Files

Both versions of the file #include the following files:

• stdint.h
• pthread.h
• ti/drivers/GPIO.h (this is a TI-RTOS package path, which locates the file within <SDK_INSTALL_DIR>/source)
• Board.h

The FreeRTOS version of the file also includes FreeRTOS.h and task.h.

The TI-RTOS version of the file also includes ti/sysbios/BIOS.h, which in this case locates the file within <SDK_INSTALL_DIR>/kernel/tirtos/packages/ti/sysbios.

The main() Function

1. The main() function begins by calling Board_initGeneral(), which the Board.h file defines to point to a board-specific function in the <board>.c file.
2. The function then sets various thread attributes in the pAttrs structure:
   • It calls pthread_attr_setdetachstate() with the PTHREAD_CREATE_DETACHED state to cause the threads created to be in the detached state, since the threads used by this application will never need to join with another thread.
   • It calls pthread_attr_setschedparam() to set the default scheduling priority for the threads to 1 (the minimum priority).
   • It calls pthread_attr_setstacksize() to set the size of the thread's stack to the value defined for the THREADSTACKSIZE constant, which is defined as a size in bytes earlier in the same file.
3. The main() function then calls pthread_create() twice.
   • The first time it creates a thread that will run the consoleThread() function. This thread runs at the default priority (1, which is the minimum). (See the console.c file for actions performed by this thread.)
   • The second time it creates a thread that will run the temperatureThread() function. This thread is set to a higher priority (2) than consoleThread. As a result, if both threads are ready to run, the temperatureThread runs first. The console thread runs when the temperature thread is sleeping or waiting for data from the I2C transfer. (See the temperature.c file for actions performed by this thread.)
   For example:

    priParam.sched_priority = 2;
    pthread_attr_setschedparam(&pAttrs, &priParam);

    retc = pthread_create(&thread, &pAttrs, temperatureThread, NULL);
    if (retc != 0) {
        /* pthread_create() failed */
        while (1);
    }

See the "SYS/BIOS POSIX Thread (pthread) Support" wiki topic for details about which POSIX APIs are supported by the SDK.

If you chose to have your application use the TI-RTOS Kernel directly instead of using POSIX, it would call the Task_create() API instead of the pthread_create() API as follows:

    Task_Params_init(&taskParams);
    taskParams.priority = 2;
    taskParams.stackSize = 768;

    temperatureTaskHandle = Task_create(temperatureThread, &taskParams, &eb);

See the TI-RTOS Kernel User's Guide for more about the TI-RTOS Kernel APIs.

4. The main() function then creates a mutex that will be used to protect the temperature variables from unsafe updates by the consoleThread() and temperatureThread().
   
5. Next the main() function called GPIO_init() to initialize the GPIO driver. This initialization is performed in main() because both threads will use the GPIO driver.
6. At this point, the two versions of the main() function diverge.
   • The TI-RTOS Kernel version simply calls BIOS_start() to start the scheduler. BIOS_start() does not return.
   • The FreeRTOS version calls vTaskStartScheduler() to start the FreeRTOS scheduler. vTaskStartScheduler() does not return.

console.c

This file is identical for all boards, RTOS kernels, and development environments. Remember to see the README.html file for information about how to open a serial session to run the example's console.

The consoleThread() function runs when the RTOS scheduler starts. First it performs some setup tasks. Later it drops into a while loop that runs until the application is halted.

Within the setup portion of the function, the consoleThread() function performs these actions:

1. Enables the Power Manager for CC3220 boards, because power management is disabled by default on the CC3220 for easier debugging.
2. Configures Board_GPIO_BUTTON1 to run the gpioButtonFxn() to wake the board in response to a button press.
3. Calls the POSIX function sem_init() to initialize an unnamed semaphore. The button press posts the semaphore and the while loop later in the consoleThread() function waits on the semaphore.
4. Initializes the parameters for the UART communication.

Within the while loop, the consoleThread() function performs these actions:

1. If uartEnabled is false (which happens when the console is closed), waits on the semaphore until the button is pressed.
2. Opens a UART for the console in blocking read and write mode by setting parameters and then calling UART_open().
3. Runs the simpleConsole() function, which uses UART_write() and UART_read() to manage the console's user interface, which accepts the following commands:

Valid Commands
--------------
h: help
q: quit and shutdown UART
c: clear the screen
t: display current temperature

4. If the "t" command is used, the values of both the temperatureC and temperatureF external variables provided by the temperatureThread are stored locally. A mutex is used to protect these operations. Without the mutex, the temperature thread, which has a higher priority, could interrupt the reading of the variables by the console thread. The result could be that the console thread printed a Celsius value that did not match the Fahrenheit value.
5. The static itoa() function is used to convert the integer temperature values to strings, and UART_write() is used to output the values to the console.
6. If the "q" command is used, the simpleConsole() function returns and the UART_close() is called. The Power Manager automatically goes to a lower-power state when the UART is closed. See the TI-RTOS Power Management User's Guide for more about power states.

temperature.c

This file is identical for all boards, RTOS kernels, and development environments.

The temperatureThread() function runs when the RTOS scheduler starts. First it performs some setup tasks. Later it drops into a while loop that runs until the application is halted.

Within the setup portion of the function, the temperatureThread() function performs these actions:

1. Initializes the I2C driver and opens the driver for use.
2. Initializes the I2C_transaction structure that will be used in the I2C_transfer().

Within the while loop, the temperatureThread() function performs these actions:

1. If an I2C transfer succeeds, a mutex is locked to make the operations that follow thread safe.
2. The temperature is extracted from the received data. (For CC3200 boards, the default is to read the TMP_DIE_TEMP register on the onboard TMP006 sensor. For all other boards, the example reads from the TMP_OBJ_TEMP register on the TMP007 sensor on the Sensors BoosterPack.)
3. The temperature is scaled to be accurate in Celsius degrees and is also converted to Fahrenheit. Both values are stored for output.
4. The mutex lock is released.
5. If the temperature is higher than 30 C, an alert message is written using GPIO_write(). Otherwise, any previous alert message is cleared.
6. The while loop sleeps for a second. If the UART is closed, this provides enough time for the device to transition to a lower-power state under the control of the Power Manager.

Note: For details about achieving better power savings on the MSP432 by using the Watchdog timer, see the TI-RTOS MSP432 Timer wiki topic.

<board>.c and <board>.h

(Where <board> is the name of your board.) These files are responsible for setting up the board specific items for the board. For example, the GPIO section configures the GPIO input pins, output pins, and LEDs. It creates an array of callback functions for the input pins and sets them to NULL. For each driver, it declares a configuration structure and sets the defaults for the attribute fields in the structure.

The <board>.c file also configures the structures used by the TI Drivers. These structures are similar for most TI Drivers. For example, a configuration data structure called <Driver>_Config is defined in <board>.c. Each driver's configuration includes a pointer to a function table, a pointer to an object, and a pointer to a set of hardware attribute settings. For more about the driver configuration structures, see the detailed reference information for the TI Driver APIs.

Board.h

This file maps board-specific constants and functions to board-independent constants and functions. The board-independent names should be used by the application so that the application code is portable.

Files for CCS, GCC, and IA

For each supported RTOS, the example contains files that are used to set up a project for the example when you import the example into a development environment. Projects for Code Composer Studio (CCS), IAR Embedded Workbench, and the GNU Compiler Collection (GCC) can be created.

Making Choices for Your Application

When using the SDK to create your own application, you should begin by making the following choices:

• Choosing which hardware target to use? See the list in SDK Components.
• Choosing which development environment to use? See Choosing a Development Environment.
• Choosing which RTOS to use? See Choosing an RTOS.
• Choosing whether to use POSIX APIs? See Choosing Whether to Use POSIX.
• Choosing which driver access method to use? See Choosing a Driver Access Method.

Choosing a Development Environment

Choose your preferred development environment. The SimpleLink MCU SDK supports all of the following development environments equally well:

• TI's Code Composer Studio (CCS)
• IAR Embedded Workbench
• GNU Compiler Collection (gcc)
• Keil (for some MCUs)

The SDK examples can be imported into any of these environments as described in the Quickstart Guide.

Choosing an RTOS

You may use either the TI-RTOS Kernel or FreeRTOS with SDK applications that use the TI Drivers.

The TI-RTOS Kernel is a scalable real-time kernel. It is designed to be used by applications that require real-time scheduling and synchronization or real-time instrumentation. It provides preemptive multi-threading, hardware abstraction, real-time analysis, and configuration tools. The Kernel is designed to minimize memory and CPU requirements on the target. The TI-RTOS Kernel was previously called SYS/BIOS. It is described in the TI-RTOS Kernel User's Guide. The Texas Instruments Wiki also links to training videos and more.

FreeRTOS is an open-source, real-time operating system kernel for embedded devices. It implements a minimalist set of functions, basic task handling and memory management. If you want to use the native FreeRTOS routines without the abstractions provided by the SDK, see the FreeRTOS website.

Choosing Whether to Use POSIX

To enable re-use of code across the TI-RTOS and FreeRTOS kernels, the SDK provides a POSIX layer.

All of the kernel-based driver examples in the SDK are POSIX-based. This allows the same code to be shared by the applications using the TI-RTOS and FreeRTOS kernels. If you want your applications to have this type of portability across kernels, we recommend that you use POSIX.

However, not all kernel features are available in the POSIX interface. If you need any OS-specific feature that is not available in the POSIX implementation, you can use a direct OS call during part of the application or the entire application.

See the "SYS/BIOS POSIX Thread (pthread) Support" wiki topic for details about which POSIX APIs are supported.

Choosing a Driver Access Method

You can choose a driver access method to fit the needs of that application. Factors that can be used to determine which method to use include:

• Does the application use TI-RTOS or FreeRTOS? Both kernels enable the use of TI Drivers.
• Do you want portability across MCUs? We recommend using the TI Drivers in this case.
• Would you like the method to provide resource allocation and abstracted power management? TI Drivers provides these features.
• Do you need to access device-specific features? Driverlib is recommended for device-specific programming. The Driverlib APIS are well-tested and are often available in ROM. They also provide an easy abstraction model for device-specific programming.
• If access to a desired feature is not available in Driverlib, or if you want full control over the registers, we recommend using the Register Access method.

You can use a combination of access methods. For example, you can use TI Drivers and Driverlib together. However, be aware that power management and resource allocation differ between access methods. For this reason, resource conflicts can arise. As long as you remain aware of the issues when using multiple access methods, it is possible to use the best features of each one.

TI Drivers

The TI Drivers provide an API interface that is compatible across the supported MCUs. Your applications can use this API with either the TI-RTOS or FreeRTOS kernel.

In order to provide a cross-MCU compatible set of APIs, some device-specific features are not available in the TI Drivers. Instead, the focus is on ease of migration. The TI Drivers abstract the common features rather than providing feature-completeness.

Driverlib

Driverlib provides device-specific APIs that abstract register and peripheral details. The goal is to provide most (if not all) of the features of the device or peripheral at an abstracted API level. Since APIs and features are closely tied to the hardware, it may not be easy to migrate the application code from one MCU to another.

This API interface provides an abstracted way to configure hardware registers. This access method acts as a translation layer for setting/resetting a register bit or set of register bits.

Register Access

This access method configures hardware registers directly by setting/resetting specific bit combinations. This method provides 100% feature coverage with no abstraction at all.

When using this method, refer to the Device Family Technical Reference Manual and the Device Datasheet. Set and reset specific bits in the registers using the definitions in the device header files included with the SDK.

TI Drivers

The SDK includes drivers for a number of peripherals. These drivers are provided in the <SDK_INSTALL_DIR>/source/ti/drivers directory. The driver examples show how to use these drivers.

Some of the drivers are available only for certain target families. Some examples of drivers supported on several target families include GPIO, I2C, Power, SPI, UART, and Watchdog. There are many more. See the detailed reference information for the complete list of TI Drivers for your target family along with full information about the APIs and configuration structures.

Driver Framework

TI drivers have a common framework for configuration and a set of APIs that all drivers implement. Applications interface with a TI driver using a top-level driver interface. This interface is configured via a set of data structures that specify one or more specific lower-level driver implementations.

TI drivers all implement the following APIs (with a few exceptions).

• Void Driver_init(Void) — Initializes the driver. This function must be called only once and before any calls to the other driver APIs. Generally, this is done before the TI-RTOS Kernel is started.
• Void Driver_Params_init(Driver_Params *params) — Initializes the driver’s parameter structure to default values. All drivers, with the exception of GPIO, implement the Params structure. The Params structure is empty for some drivers.
• Driver_Handle Driver_open(UInt index, Driver_Params *params) — Opens the driver instance specified by the index with the params provided. If the params field is NULL, the driver uses default values. This function returns a handle that will be used by other driver APIs and should be saved. If there is an error opening the driver or the driver has already been opened, Driver_open() returns NULL.
• Void Driver_close(Driver_Handle handle) — Closes the driver instance that was opened, specified by the driver handle returned during open. This function closes the driver immediately, without checking to see if the driver is currently in use. It is up to the application to determine when to call Driver_close() and to ensure it doesn’t disrupt on-going driver activity.

Drivers Porting Layer (DPL)

The Drivers Porting Layer allows the TI drivers to work with either the TI-RTOS or FreeRTOS kernel.

The TI Drivers use DPL APIs provided by the TI-RTOS and FreeRTOS Kernels for clock, interrupt, mutex, semaphore, and other services. However, the DPL abstracts the RTOS kernel functionality used by the drivers so that the application is not dependent on the TI-RTOS Kernel and can instead make use of the FreeRTOS kernel.

Board Files

TI Driver examples contain a board-specific C file (and its companion header file). The filenames are board.c and board.h, where board is the name of the board. All the TI Driver examples for a specific board use the same board files. These files are considered part of the example application, and you can modify them as needed.

The board files perform board-specific configuration of the drivers provided by the SDK. For example, they typically configure the GPIO ports and pins and configure use of the board LEDs.

Debugging Output

The Display middle-ware driver is the recommended strategy for providing “printf” style debugging. It is RTOS independent. The Display module supports sending debug output by different methods (for example, UART, IDE Console, and LCD). Application writers can also provide their own custom Display implementation.

Many of the TI Driver examples use the Display module to send debugging information out a UART or LCD. The main API is the Display_printf() functions. This function is very similar to the standard printf() function. The configuration for the Display module is in the <board>.c file. For details about the Display module functionality, refer to the reference documentation .

Note: The default printf() API is not recommended for use with SDK applications due to the impact on real-time performance and code footprint size.

Note: The System module in the TI-RTOS Kernel is available for applications that use the TI-RTOS native APIs (instead of the POSIX APIs). The System module functionality is unchanged from previous versions and will continue to be supported. The TI-RTOS "release" configuration uses SysCallback as the System support proxy to minimize footprint and performance impacts. The TI-RTOS "debug" configuration uses SysMin as the System support proxy, which slightly impacts footprint and performance but allows viewing of the System_printf debug output in the RTOS Object Viewer (ROV). Refer to the Configuration with TI-RTOS section for more details about the release and debug versions.

TI-RTOS Kernel

The SDK includes the TI-RTOS Kernel.

TI-RTOS provides a rich set of system-level embedded software, including multi-tasking, power management, device drivers, and instrumentation. TI-RTOS includes support for the TI-RTOS Kernel and FreeRTOS. Through the use of industry-standard POSIX pthread APIs, TI-RTOS enables other kernels (schedulers) to be integrated. TI-RTOS is delivered in the SDK in a consistent manner across the various SimpleLink SDKs.

The TI-RTOS Kernel is a scalable real-time kernel. The kernel is designed to be used by applications that require real-time scheduling and synchronization or real-time instrumentation. It provides preemptive multi-threading, hardware abstraction, real-time analysis, and configuration tools. The Kernel is designed to minimize memory and CPU requirements on the target. This kernel was previously called SYS/BIOS.

The TI-RTOS Kernel is described in the TI-RTOS Kernel User's Guide. Additionally, detailed reference information is provided for all the TI-RTOS Kernel APIs. The Texas Instruments Wiki links to training videos and more for the TI-RTOS Kernel.

Organization of TI-RTOS Kernel Moduless

The TI-RTOS Kernel and the XDCtools underlying tooling it uses are organized into sets of "packages," each of which delivers a subset of the product's functionality. The package names reflect the physical layout of the package within the SDK installation. For example, the ti.sysbios.knl package files can be found in the <SDK_INSTALL_DIR>/kernel/tirtos/packages/ti/sysbios/knl directory.

Each package provides one or more modules. Each module, in turn, provides APIs for working with that module. APIs have function names of the form Module_actionDescription(). For example, Task_setPri() sets the priority of a Task thread.

Using TI-RTOS Kernel Modules

In order to use a module, your application must include the standard SYS/BIOS header files and the header file for that particular module. For example, include these header files to enable use of the Task module APIs:

#include <xdc/std.h> /* initializes XDCtools */
#include <ti/sysbios/BIOS.h> /* initializes SYS/BIOS */
#include <ti/sysbios/knl/Task.h> /* initializes Task module */

Configuration with TI-RTOS

All TI-RTOS applications need a TI-RTOS configuration file (.cfg file). This file specifies how the kernel will be built. There are two methods for including the configuration in the application.

1. Part of the same project: The .cfg file can be part of the application project. When the application is built, the .cfg file is also “built” and the generated files (source and linker file) are included in the application automatically. This method allows for fine tuning of the kernel for a specific application. Examples that use this method are in the examples\rtos\<board>\sysbios directory.
2. Part of a separate shared project: The application can point to a “shared” configuration project. The SDK provides the following two configurations in the kernel\tirtos\builds\<board> directory:
   1. release: A non-instrumented version of the TI-RTOS kernel. The main features are present in this version of the kernel--for example, Tasking, Mailboxes, Semaphores, and Clock. This version has a small footprint and better performance than the debug version. This version is not the absolute minimum footprint because your application may not use all the RTOS kernel features.
   2. debug: An instrumented version of the kernel. This version enables asserts, logging, enhanced exception handling, and more. This version has the same RTOS feature set as the release version. This version is intended to be used during development. The separate configuration project method allows a configuration to be used by multiple applications. The build time for the application is faster, since it does not need to rebuild the kernel. The examples in the examples\rtos\<board> directory tree use this method.

Note: We recommend that you do not change the release.cfg and debug.cfg files. Instead refer to the following section if you want to create a new configuration.

For CCS users, when you import an example that uses Method 2, the separate configuration project specified by the example is also automatically imported.

Changing the TI-RTOS Configuration

The steps are different depending on whether the .cfg file is stored within your application project or in a separate project referenced by your application project.

Application Project Contains the .cfg File

You can simply edit the configuration file (via a text editor or the xGCONF tool in CCS). When the application is built, the kernel will be rebuilt also. This method applies for CCS, IAR and command line builds.

Application Project Does Not Contain the .cfg File

The steps are different depending on whether you are using CCS or IAR.

CCS Project

CCS projects can point to a separate configuration project in the Project Properties dialog in the Build->Dependencies tab.

Note: Don't confuse the "RTOS configuration" with the "CCS Build Configuration". The RTOS configuration does not need to correspond to the CCS Build Configuration (often also called Debug or Release).

By default, all TI driver examples use the "release" TI-RTOS configuration for both CCS Build Configurations.

To select a different configuration, import the desired configuration into CCS. To do this, follow these steps:

1. Choose Project->Import CCS Project from the CCS menus.
2. Next to Select search-directory, click Browse.
3. Navigate to <SDK_INSTALL_DIR>\kernel\tirtos\builds\<board> directory and then either debug or release. Then click OK.
4. Check the box for the development environment you will use to build your application (CCS or GCC), and click Finish.

5. Choose Project->Properties and select the Build category and the Dependencies tab.
6. Select the old RTOS configuration and click Remove.
7. Click Add and select the project you imported. Then click OK.

When the application is rebuilt, the new kernel will be build and included.

IAR and Makefile

The IAR and command line example projects point to a specific shared configuration using a line similar to the following in the makefile:

KERNEL_BUILD :=  $(SIMPLELINK_CC32XX_SDK_INSTALL_DIR)/kernel/tirtos/builds/<board>/release

To use the debug version of the kernel, simply change “release” to “debug” and rebuild. If you created your own custom configuration (see below), adjust the path accordingly.

Creating Your Own TI-RTOS Configuration

Some users may want to create a custom TI-RTOS configuration. Common reasons for creating a custom configuration are to:

• Reduce the code footprint. For example, you might lower the number of task priorities or omit the Events module.
• Create a hybrid configuration. For example, you might add only Assert checking to the release configuration.
• Add advanced kernel features. For example, you might write your own Error handler.

Once a new configuration is created and built, it can be used as described in the Changing TI-RTOS configuration section.

Creating a Custom TI-RTOS Configuration with CCS

A custom shared TI-RTOS configuration file can be created by following these steps:

1. Import either a debug or release configuration file project into CCS (for example, <SDK_INSTALL_DIR>\kernel\tirtos\builds\<board>\debug\ccs). Pick the one (debug vs. release) that is closer to the custom configuration you want. You can simply do a text diff of the files to see the differences. Note: When importing the TI-RTOS configuration project, all files are copied into the project. Any changes you make have no impact on the project files stored as part of the SDK product.
2. Rename the project to something meaningful for you (for example, tirtos_builds_CC3220S_LAUNCHXL_widget_ccs).
3. We recommend that you also rename the .cfg file. This makes it easier to recognize when the file is open in the editor. (for example, widget.cfg)
4. Edit the .cfg as desired:
   1. For text editing, right-click on the .cfg file and choose Open With->XDCscript editor (or Text editor) or use your favorite text editor.
   2. For graphical editing, right-click on the .cfg file and choose Open With->XGCONF. See Chapter 2 of the TI-RTOS Kernel User's Guide for information about using the XGCONF editor.
5. Rebuild the project using CCS.

Creating a Custom TI-RTOS Configuration with IAR and the Command Line

A custom shared TI-RTOS configuration file can be created by following these steps:

1. Copy either the debug or release directory (whichever one is closer to the custom configuration you want) to a desired location. For example, copy <SDK_INSTALL_DIR>\kernel\tirtos\builds\<board>\debug to c:\widgetconfig. Do not use spaces in the destination path.
2. We recommend that you also rename the .cfg file. This makes it easier to recognize when the file is open in the editor. (for example, widget.cfg)
3. In the makefile of the desired toolchain (for example, c:\widgetconfig\ccs\makefile) make the following changes:
   1. Define SIMPLELINK_<target>_SDK_INSTALL_DIR to point to your <SDK_INSTALL_DIR> location. For example: SIMPLELINK_MSP432_SDK_INSTALL_DIR ?= c:\ti\simplelink_msp432_sdk_1_10_00_76 (Your location will differ.)
   2. Change the name of the configuration file. The file must end with .cfg and not contain spaces. For example in <SDK_INSTALL_DIR>\kernel\tirtos\builds\<board>\debug\ccs\makefile, change “debug.cfg” or “release.cfg” to "widget.cfg".

CFG_FILE   ?= ../widget.cfg

4. Edit the .cfg as desired in your favorite text editor.
5. Build the project using a command similar to the following:

C:\widgetconfig\ccs>c:\ti\xdctools_3_32_01_22_core\gmake

FreeRTOS Kernel

FreeRTOS is an open-source, real-time operating system kernel for embedded devices. It implements a minimalist set of functions, basic task handling and memory management.

The FreeRTOS kernel has the following characteristics:

• Preemptive tasks
• Small footprint
• Written in C and compiled with various C compilers
• Unlimited number of tasks can run at the same time
• Implements queues, binary and counting semaphores, and mutexes
• Inter-task communication is accomplished using queues

The SDK provides support for FreeRTOS but does not install FreeRTOS. You can download the FreeRTOS source files via the FreeRTOS website. The SDK does install the Driver Porting Layer (DPL) and POSIX abstractions to allow FreeRTOS to be used with the other SDK components.

FreeRTOS does not provide a network communication stack, drivers for external hardware, or access to a file system. Those capabilities are covered by the TI Driver layer.

In the SDK, all FreeRTOS application routines are abstracted using the following:

• A POSIX layer, which was designed for use with this SDK
• A Driver Porting Layer (DPL) for use by the TI Drivers

If you want to use the native FreeRTOS routines without the abstractions provided by the SDK, documentation is provided on the www.freertos.org website.

You can find example projects in the examples/rtos/ folder for all supported IDEs. No native FreeRTOS examples are provided in this SDK.

Using FreeRTOS with CCS

In order to use FreeRTOS within CCS, you must specify the location of the FreeRTOS installation. To do this, follow these steps:

1. In CCS, choose Window->Preferences from the menus.
2. Select the General->Workspace->Linked Resource category.
3. Click New and add a link with the following settings:
   • Name: FREERTOS_INSTALL_DIR
   • Value: the location of you FreeRTOS installation

These steps only need to be performed once per CCS workspace that you use.

Configuration with FreeRTOS

The FreeRTOS configuration file (FreeRTOSConfig.h) is in the <SDK_INSTALL_DIR>\kernel\freertos\builds\<board>\release directory. The library can be built with the supported compiler tools.

Note: We recommend that you do not change the FreeRTOSConfig.h file. Instead refer to the below section on how to create a new configuration.

Creating a Custom FreeRTOS Configuration

For FreeRTOS, only a "release" RTOS configuration project is provided. Some users may want to create a custom FreeRTOS configuration. Common reasons for creating a custom configuration are to:

• Reduce the code footprint. For example, you might lower the number of task priorities.
• Add advanced kernel features. For example, you might want a different implementation of configASSERT().

Once a new configuration is created and built, it can be used as described in the Changing FreeRTOS configuration section.

Creating a Custom FreeRTOS Configuration with CCS

A custom shared FreeRTOS configuration file can be created by following these steps:

1. Import the release configuration file project into CCS (for example, <SDK_INSTALL_DIR>\kernel\freertos\builds\<board>\release\ccs). Note: When importing the FreeRTOS configuration project, all files are copied into the project. Any changes you make have no impact on the project files stored as part of the SDK product.
2. Rename the project to something meaningful for you (for example, freertos_builds_CC3220S_LAUNCHXL_widget_ccs).
3. Edit the FreeRTOSConfig.h file as desired.
4. Rebuild the project using CCS.

Creating a Custom FreeRTOS Configuration with IAR and the Command Line

A custom shared FreeRTOS configuration file can be created by following these steps:

1. Copy the release directory to a desired location. For example copy <SDK_INSTALL_DIR>\kernel\freertos\builds\<board>\release to c:\widgetconfig. Do not use spaces in the path.
2. In the makefile of the desired toolchain (for example, c:\widgetconfig\ccs\makefile) change the definition of SIMPLELINK_<target>_SDK_INSTALL_DIR to point to your <SDK_INSTALL_DIR>. For example, SIMPLELINK_MSP432_SDK_INSTALL_DIR ?= c:\ti\ simplelink_msp432_sdk_1_10_00_76 (Your location will differ.)
3. Edit the FreeRTOSConfig.h file as desired.
4. Rebuild the project using a command similar to the following:

C:\widgetconfig\ccs>c:\ti\xdctools_3_32_01_22_core\gmake

Changing the FreeRTOS Configuration

After you create a custom configuration, you can cause your application to use that configuration. The steps are different depending on whether you are using CCS or IAR.

CCS Project

CCS projects can point to a separate configuration project in the Project Properties dialog in the Build->Dependencies tab.

Note: Don't confuse the "RTOS configuration" with the "CCS Build Configuration". The RTOS configuration does not need to correspond to the CCS Build Configuration (often called Debug or Release).

To select a different configuration, import the desired configuration into CCS. To do this, follow these steps:

1. Choose Project->Import CCS Project from the CCS menus.
2. Next to Select search-directory, click Browse.
3. Navigate to the directory where you created your custom configuration. Then click OK.
4. Check the box for the development environment you will use to build your application (CCS or GCC), and click Finish.

5. Choose Project->Properties and select the Build category and the Dependencies tab.
6. Select the old configuration and click Remove.
7. Click Add and select the project you imported. Then click OK.

When the application is rebuilt, the new kernel will be build and included.

IAR and Makefile

The IAR and command line example projects point to a specific shared configuration using a line similar to the following in the makefile:

KERNEL_BUILD :=  $(SIMPLELINK_CC32XX_SDK_INSTALL_DIR)/kernel/freertos/builds/<board>/release

To use a different version of the kernel, simply change “release” to your custom configuration path and name. Then rebuild.

Third-Party Components

The following third-party components can be used with the SDK.

CMSIS

The Cortex Microcontroller Software Interface Standard (CMSIS) is a common hardware abstraction layer for the Cortex-M processor series. It defines generic tool interfaces.

The CMSIS provides consistent device support and simple software interfaces to the processor and the peripherals. This simplifies software re-use, reducing the learning curve for microcontroller developers, and reducing the time to market for new devices. The CMSIS was created to enable software components from multiple middleware vendors to be combined.

There are several components in the CMSIS specifications, many of which are supported by the SDK and its tools infrastructure. Detailed information on these CMSIS components can be found at http://www.keil.com/pack/doc/CMSIS/General/html/index.html

The ARMCLANG and CMSIS-SVD components are not part of the SDK. They are shipped by Keil.

The benefits of the CMSIS-Core and CMSIS include:

• CMSIS reduces the learning curve, development costs, and time-to-market. Developers can write software more quickly using a variety of easy-to-use, standardized software interfaces.
• Consistent software interfaces improve software portability and re-usability. Generic software libraries and interfaces provide a consistent software framework.
• CMSIS provides a compiler-independent layer. This allows you to use different compilers. CMSIS is supported by all mainstream compilers (ARMCC, IAR, and GNU).

CMSIS Header Files

The SDK includes specific releases of CMSIS core files that have been tested and validated with the components the SDK. The CMSIS files include the following:

• The CMSIS-Core header files are specific releases from https://github.com/ARM-software/CMSIS/tree/master/CMSIS/Include
• The cmsis_ccs.h file is shipped as part of Texas Instruments' Code Composer Studio
• The cmsis_iar.h file is shipped as part of IAR

FatFs

FatFs is an open-source FAT file system module intended for use in embedded systems. The API used by your applications is generic to all FatFs implementations, and is described and documented at http://elm-chan.org/fsw/ff/00index_e.html. Details about the FatFs API are not discussed here. Instead, this section gives a high-level explanation about how it is integrated with the TI Drivers.

In order to use FatFs in SDK applications, use the files in the <SDK Install>\source\third_party\fatfs directory.

The FatFs drivers provided by the SDK enable you to store data on removable storage media, such as Secure Digital (SD) cards. Such storage may be a convenient way to transfer data between embedded devices and conventional PC workstations.

FatFs and TI Drivers

The SDK provides a FatFS module and extends this module by supplying "FatFs" drivers that link into the FatFs implementation. The FatFS drivers are aware of the multi-threaded environment and protect themselves with OS primitives.

From the start of this data flow to the end, the components involved behave as follows:

• Application. The top application layer calls the basic open, close, read, and write functions. Users who are familiar with FatFs can easily use the FatFs API, which is documented at the module’s download site. Alternatively, the application can also connect the C input/output (C I/O) runtime support library in TI’s Code Generation Tools to FatFs. You can call familiar functions such as fopen(), fclose(), fread(), and fwrite(). Functionally, the C I/O interface and the FatFs APIs perform the same operations (with a few exceptions described in the following section).

• FatFS module. The next layer, the source/third_party/FatFS module, is provided as part of the SDK. This module handles the details needed to manage and use the FAT file system, including the media’s boot sector, FAT tables, root directories, and data regions. It also protects its functions in a multi-threaded environment. Internally, the FatFS module makes low-level data transfer requests to the Disk IO functions described on the FatFs product web page. Implementations of this set of functions are called "FatFs drivers" in this document.

• diskIO Function table. To allow products to provide multiple FatFs drivers, the FatFS module contains a simple driver table. You can use this to register multiple FatFs drivers at runtime. Based on the drive number passed by FatFs, the driver table routes FatFs calls to a particular FatFs driver.

• FatFs drivers. The last layer in the figure above is the FatFs drivers. The SDK comes with pre-built FatFs drivers that plug into the FatFS module. A FatFs driver has no knowledge of the internal workings of FatFs. Its only task is to perform disk-specific operations such as initialization, reading, and writing. The FatFs driver performs read and write operations in data block units called sectors (commonly 512 bytes). Details about writing data to the device are left to the particular FatFs driver, which typically accesses a peripheral’s hardware registers or uses a driver library.

Using FatFs

The subsections that follow show how to configure FatFs, how to prepare the FatFs drivers for use in your application, and how to open files. For details about performing other file-based actions once you have opened a file, see the FatFs APIs described on http://elm-chan.org/fsw/ff/00index_e.html in the "Application Interface" section or the standard C I/O functions.

The FatSD and FatSDraw examples use FatFs with the SDSPI driver.

Defining Drive Numbers

Calls to the open() functions of individual FatFs drivers—for example, SDSPI_open()—require a drive number argument. Calls to the C I/O fopen() function and the FatFs APIs also use the drive number in the string that specifies the file path. The following C code defines driver numbers to be used in such functions:

/* Drive number used for FatFs */
#define SD_DRIVE_NUM 0
#define USB_DRIVE_NUM 1

Here are some statements from the FatSD USB Copy example that use these drive number definitions. Note that STR(SD_DRIVE_NUM) uses a MACRO that expands SD_DRIVE_NUM to 0.

SDSPI_Handle sdspiHandle;
SDSPI_Params sdspiParams;
FILE *src;
const Char inputfilesd[] = "fat:"STR(SD_DRIVE_NUM)":input.txt";

/* Mount and register the SD Card */
SDSPI_Params_init(&sdspiParams);
sdspiHandle = SDSPI_open(Board_SDSPI0, SD_DRIVE_NUM, &sdspiParams);

/* Open the source file */
src = fopen(inputfilesd, "r");

Preparing FatFs Drivers

In order to use a FatFs driver in an application, you must do the following:

• Include the header file for the driver. For example:

    #include <ti/drivers/SDSPI.h>

• Run the initialization function for the driver. All drivers have init() functions—for example, SDSPI_init()—that need to be run in order to set up the hardware used by the driver. Typically, these functions are run from main(). In the examples, a board-specific initialization function for the driver is run instead of running the driver’s initialization function directly. For example:

    SDSPI_init();

• Open the driver. The application must open the driver before the FatFs can access the drive and its FAT file system. Similarly, once the drive has been closed, no other FatFs calls shall be made. All drivers have open() functions—for example, SDSPI_open()—that require a drive number to be passed in as an argument. For example:

    sdspiHandle = SDSPI_open(Board_SDSPI0, SD_DRIVE_NUM, NULL);

See the SDSPI Driver for details about the FatFs driver APIs.

Opening Files Using FatFs APIs

Details on the FatFs APIs can be found at http://elm-chan.org/fsw/ff/00index_e.html in the "Application Interface" section.

The drive number needs to be included as a prefix in the filename string when you call f_open() to open a file. The drive number used in this string needs to match the drive number used to open the FatFs driver. For example:

res = f_open(&fsrc, “SD_DRIVE_NUM:source.dat”, FA_OPEN_EXISTING | FA_READ);

res = f_open(&fdst, “USB_DRIVE_NUM:destination.dat”, FA_CREATE_ALWAYS | FA_WRITE);

A number of other FatFs APIs require a path string that should include the drive number. For example, f_opendir(), f_mkdir(), f_unlink(), and f_chmod().

Although FatFs supports up to 10 (0-9) drive numbers, the diskIO function table supports only up to 4 (0-3) drives. You can modify this default by changing the definition of _VOLUMES in the ffconf.h file in the FatFS module. You will then need to rebuild the TI Drivers and FatFS modules.

It is important to use either the FatFs APIs or the C I/O APIs for file operations. Mixing the APIs in the same application can have unforeseen consequences.

Opening Files Using C I/O APIs

The C input/output runtime implementation for FatFs works similarly to the FatFs API. However, you must add the file name prefix configured for the FatFS module ("fat" by default) and the logical drive number as prefixes to the filename. The file name prefix is extracted from the filename before it gets passed to the FatFs API.

In this example, the default file name prefix is used and the drive number is 0:

fopen(“fat:0:input.txt”, "r");

It is important to use either the FatFs APIs or the C I/O APIs for file operations. Mixing the APIs in the same application can have unforeseen consequences.

Cautionary Notes

Number of Volumes Mounted: The FatFS implementation allows up to four unique volumes (or drives) to be registered and mounted.

FatFs actions and Low-priority Tasks: FatFs drivers perform data block transfers to and from physical media. Depending on the FatFs driver, writing to and reading from the disk could prevent lower-priority tasks from running during that time. If the FatFs driver blocks for the entire transfer time, only higher-priority SYS/BIOS Tasks, Swis or Hwis can interrupt the Task making FatFs calls. In such cases, the application developer should consider how often and how much data needs to be read from or written to the media.

Buffering: RAM Usage vs. Disk Operations: By default the FatFS module keeps a complete sector buffered for each opened file. While this requires additional RAM, it helps mitigate frequent disk operations when operating on more than one file simultaneously.

Use of long file names or XFAT: The FatFS libraries are configured for use without Long File Name (VFAT) or XFAT support. If you chose to reconfigure and build FatFS to include these features, you may be required to license the appropriate patents from Microsoft. For more information, refer to: http://elm-chan.org/fsw/ff/en/appnote.html