FreeRTOS on the EK-TM4C123GXL LaunchPad Board

Getting latest FreeRTOS working in CCS under ubuntu, and the GNU GCC compiler that ships with CCS, on a EK-TM4C123GXL Launchpad from ground zero. This getting started guide demonstrates the use of FreeRTOS on the EK-TM4C123GXL LaunchPad Board.

FreeRTOS Demo Application

The application blinks the user-selected LED at a user-selected frequency.

To select the LED press the left button
To select the frequency press the right button.
The UART outputs the application status at 115,200 baud, 8-n-1 mode.

This application utilizes FreeRTOS to perform the tasks in a concurrent fashion.
The following tasks are created:

An LED task, which blinks the user-selected on-board LED at a user-selected rate (changed via the buttons).
A Switch task, which monitors the buttons pressed and passes the information to LED task.

In addition to the tasks, this application also uses the following FreeRTOS resources:

A Queue to enable information transfer between tasks.
A Semaphore to guard the resource, UART, from access by multiple tasks at the same time.
A non-blocking FreeRTOS Delay to put the tasks in blocked state when they have nothing to do.

FreeRTOS_ON_TM4C

► Install Code Composer Studio and Tivaware for C Series (Skip this step if you have working CCS6.2.x.x OR CCS7.x.x.x & Tivaware for C Series Installed)

► Fetch FreeRTOS Source

► Create FreeRTOS CCS Demo Project

With the project created, we are now going to import FreeRTOS Source first.

► Right-click on the project (freertos_on_tm4c123) in the "Project Explorer", and make a New folder, Call it "FreeRTOS".

Now we'll import the necessary FreeRTOS (source/header) files into this folder:

► Import FreeRTOS Source Files

Next, we will import the FreeRTOS example program, drivers and uartstdio files from Tivaware Examples.

► Import Tivaware FreeRTOS Demo Source Files

► Create Path/Build variable CCS

With FreeRTOS and tivaware in our project, we need to make sure the C/C++ compiler is configured properly to search the include and portable folders since FreeRTOS (and our project) depend on it.

► Configure FreeRTOS Demo Project Include Search Path

There are few GCC options we're going to tune.

► Configure FreeRTOS Demo Project GCC Options

FreeRTOS requires the use of several hardware interrupts/peripherals to function, notably the SysTick feature for its RTOS tick and the software interrupt calls SVCall and PendSV for its internal operation. Let's configure these interrupt handlers.

► Configure FreeRTOS Demo Project Interrupt Handlers

► Link the TivaWare libdriver.a file to FreeRTOS Demo Project

To get FreeRTOS into a state where we can compile it, a FreeRTOSConfig.h file is required and it looks for it. Add this file inside the FreeRTOS/include folder since we have that folder in our include path already:

After inluding FreeRTOS/include/FreeRTOSConfig.h, let's try to build our project:

► Build FreeRTOS Demo Project

Now let's make FreeRTOS actually run.

► FreeRTOS Demo Project Debug Configuration

► Load, Debug, Run - FreeRTOS Demo Project