Texas Instruments EK-TM4C123GXL User manual

Copyright © 2012-2016
Texas Instruments Incorporated
SW-EK-TM4C123GXL-UG-2.1.3.156
USER’S GUIDE
EK-TM4C123GXL Firmware Development
Package

Copyright
Copyright © 2012-2016 Texas Instruments Incorporated. All rights reserved. Tiva and TivaWare are trademarks of Texas Instruments Instruments. ARM
and Thumb are registered trademarks and Cortex is a trademark of ARM Limited. Other names and brands may be claimed as the property of others.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semicon-
ductor products and disclaimers thereto appears at the end of this document.
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Austin, TX 78746
www.ti.com/tiva-c
Revision Information
This is version 2.1.3.156 of this document, last updated on July 25, 2016.
2 July 25, 2016

Table of Contents
Table of Contents
Copyright ..................................................... 2
Revision Information ............................................... 2
1 Introduction ................................................. 5
2 Example Applications ........................................... 7
2.1 Bit-Banding (bitband) ............................................ 7
2.2 Blinky (blinky) ................................................ 7
2.3 FreeRTOS Example (freertos_demo) ................................... 7
2.4 GPIO JTAG Recovery (gpio_jtag) ..................................... 8
2.5 Hello World (hello) .............................................. 8
2.6 Interrupts (interrupts) ............................................ 8
2.7 MPU (mpu_fault) ............................................... 8
2.8 Project Zero (project0) ............................................ 9
2.9 EK-TM4C123GXL Quickstart Application (qs-rgb) ............................ 9
2.10 Timer (timers) ................................................ 9
2.11 UART Echo (uart_echo) ........................................... 10
2.12 uDMA (udma_demo) ............................................ 10
2.13 USB Generic Bulk Device (usb_dev_bulk) ................................. 10
2.14 USB HID Gamepad Device (usb_dev_gamepad) ............................. 10
2.15 USB Serial Device (usb_dev_serial) .................................... 11
3 Buttons Driver ............................................... 13
3.1 Introduction .................................................. 13
3.2 API Functions ................................................ 13
3.3 Programming Example ........................................... 14
4 RGB LED Driver .............................................. 15
4.1 Introduction .................................................. 15
4.2 API Functions ................................................ 15
4.3 Programming Example ........................................... 19
IMPORTANT NOTICE ............................................... 20
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Table of Contents
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Introduction
1 Introduction
The Texas Instruments® Tiva™ C Series EK-TM4C123GXL evaluation board is a low cost platform
that can be used for software development and to prototype a hardware design. It contains a
Tiva C Series ARM® Cortex™-M4F-based microcontroller, a USB device port, two push buttons,
and a RGB LED that can be used to exercise the peripherals on the microcontroller. Additionally,
most of the microcontroller’s pins are brought to headers, allowing for easy connection to other
hardware for the purposes of prototyping. The outer rows of header pins are compatible with the
MSP430™ Launchpad.
This document describes the example applications that are provided for this evaluation board.
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Introduction
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Example Applications
2 Example Applications
The example applications show how to use features of the Cortex-M4F microprocessor, the periph-
erals on the Tiva C Series microcontroller, and the drivers provided by the peripheral driver library.
These applications are intended for demonstration and as a starting point for new applications.
There is an IAR workspace file (ek-tm4c123gxl.eww) that contains the peripheral driver li-
brary project, USB library project, and all of the board example projects, in a single, easy to use
workspace for use with Embedded Workbench version 6.
There is a Keil multi-project workspace file (ek-tm4c123gxl.mpw) that contains the peripheral
driver library project, USB library project, and all of the board example projects, in a single, easy to
use workspace for use with uVision.
All of these examples reside in the examples/boards/ek-tm4c123gxl subdirectory of the
firmware development package source distribution.
2.1 Bit-Banding (bitband)
This example application demonstrates the use of the bit-banding capabilities of the Cortex-M4F
microprocessor. All of SRAM and all of the peripherals reside within bit-band regions, meaning that
bit-banding operations can be applied to any of them. In this example, a variable in SRAM is set to
a particular value one bit at a time using bit-banding operations (it would be more efficient to do a
single non-bit-banded write; this simply demonstrates the operation of bit-banding).
2.2 Blinky (blinky)
A very simple example that blinks the on-board LED using direct register access.
2.3 FreeRTOS Example (freertos_demo)
This application demonstrates the use of FreeRTOS on Launchpad.
The application blinks the user-selected LED at a user-selected frequency. To select the LED press
the left button and 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.
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Example Applications
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.
For additional details on FreeRTOS, refer to the FreeRTOS web page at:
http://www.freertos.org/
2.4 GPIO JTAG Recovery (gpio_jtag)
This example demonstrates changing the JTAG pins into GPIOs, aint32_t with a mechanism to
revert them to JTAG pins. When first run, the pins remain in JTAG mode. Pressing the left button
will toggle the pins between JTAG mode and GPIO mode. Because there is no debouncing of the
push button (either in hardware or software), a button press will occasionally result in more than
one mode change.
In this example, four pins (PC0, PC1, PC2, and PC3) are switched.
UART0, connected to the ICDI virtual COM port and running at 115,200, 8-N-1, is used to display
messages from this application.
2.5 Hello World (hello)
A very simple “hello world” example. It simply displays “Hello World!” on the UART and is a starting
point for more complicated applications.
UART0, connected to the Virtual Serial Port and running at 115,200, 8-N-1, is used to display
messages from this application.
2.6 Interrupts (interrupts)
This example application demonstrates the interrupt preemption and tail-chaining capabilities of
Cortex-M4 microprocessor and NVIC. Nested interrupts are synthesized when the interrupts have
the same priority, increasing priorities, and decreasing priorities. With increasing priorities, pre-
emption will occur; in the other two cases tail-chaining will occur. The currently pending interrupts
and the currently executing interrupt will be displayed on the display; GPIO pins E1, E2 and E3 will
be asserted upon interrupt handler entry and de-asserted before interrupt handler exit so that the
off-to-on time can be observed with a scope or logic analyzer to see the speed of tail-chaining (for
the two cases where tail-chaining is occurring).
2.7 MPU (mpu_fault)
This example application demonstrates the use of the MPU to protect a region of memory from
access, and to generate a memory management fault when there is an access violation.
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Example Applications
UART0, connected to the virtual serial port and running at 115,200, 8-N-1, is used to display mes-
sages from this application.
2.8 Project Zero (project0)
This example demonstrates the use of TivaWare to setup the clocks and toggle GPIO pins to make
the LED’s blink. This is a good place to start understanding your launchpad and the tools that can
be used to program it.
2.9 EK-TM4C123GXL Quickstart Application (qs-rgb)
A demonstration of the Tiva C Series LaunchPad (EK-TM4C123GXL) capabilities.
Press and/or hold the left button to traverse towards the red end of the ROYGBIV color spectrum.
Press and/or hold the right button to traverse toward the violet end of the ROYGBIV color spectrum.
If no input is received for 5 seconds, the application will start automatically changing the color
displayed.
Press and hold both left and right buttons for 3 seconds to enter hibernation. During hibernation,
the last color displayed will blink for 0.5 seconds every 3 seconds.
The system can also be controlled via a command line provided via the UART. Configure your host
terminal emulator for 115200, 8-N-1 to access this feature.
Command ’help’ generates a list of commands and helpful information.
Command ’hib’ will place the device into hibernation mode.
Command ’rand’ will initiate the pseudo-random color sequence.
Command ’intensity’ followed by a number between 0 and 100 will set the brightness of the
LED as a percentage of maximum brightness.
Command ’rgb’ followed by a six character hex value will set the color. For example ’rgb
FF0000’ will produce a red color.
2.10 Timer (timers)
This example application demonstrates the use of the timers to generate periodic interrupts. One
timer is set up to interrupt once per second and the other to interrupt twice per second; each
interrupt handler will toggle its own indicator on the display.
UART0, connected to the Virtual Serial Port and running at 115,200, 8-N-1, is used to display
messages from this application.
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Example Applications
2.11 UART Echo (uart_echo)
This example application utilizes the UART to echo text. The first UART (connected to the USB
debug virtual serial port on the evaluation board) will be configured in 115,200 baud, 8-n-1 mode.
All characters received on the UART are transmitted back to the UART.
2.12 uDMA (udma_demo)
This example application demonstrates the use of the uDMA controller to transfer data between
memory buffers, and to transfer data to and from a UART. The test runs for 10 seconds before
exiting.
UART0, connected to the FTDI virtual COM port and running at 115,200, 8-N-1, is used to display
messages from this application.
2.13 USB Generic Bulk Device (usb_dev_bulk)
This example provides a generic USB device offering simple bulk data transfer to and from the host.
The device uses a vendor-specific class ID and supports a single bulk IN endpoint and a single bulk
OUT endpoint. Data received from the host is assumed to be ASCII text and it is echoed back with
the case of all alphabetic characters swapped.
A Windows INF file for the device is provided on the installation CD and in the C:/ti/TivaWare-for-
C-Series/windows_drivers directory of TivaWare C series releases. This INF contains information
required to install the WinUSB subsystem on Windowi16XP and Vista PCs. WinUSB is a Win-
dows subsystem allowing user mode applications to access the USB device without the need for a
vendor-specific kernel mode driver.
A sample Windows command-line application, usb_bulk_example, illustrating how to connect to
and communicate with the bulk device is also provided. The application binary is installed as
part of the ”Windows-side examples for USB kits” package (SW-USB-win) on the installation CD
or via download from http://www.ti.com/tivaware . Project files are included to allow the
examples to be built using Microsoft VisualStudio 2008. Source code for this application can be
found in directory TivaWare-for-C-Series/tools/usb_bulk_example.
2.14 USB HID Gamepad Device (usb_dev_gamepad)
This example application turns the evaluation board into USB game pad device using the Human
Interface Device gamepad class. The buttons on the board are reported as buttons 1 and 2. The
X, Y, and Z coordinates are reported using the ADC input on GPIO port E pins 1, 2, and 3. The X
input is on PE3, the Y input is on PE2 and the Z input is on PE1. These are not connected to any
real input so the values simply read whatever is on the pins. To get valid values the pins should
have voltage that range from VDDA(3V) to 0V. The blue LED on PF5 is used to indicate gamepad
activity to the host and blinks when there is USB bus activity.
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