Texas Instruments Stellaris LM3S1968 User manual

EK-LM3S1968-03 Copyright © 2007–2010 Texas Instruments
User’s Manual
Stellaris® LM3S1968 Evaluation Board

2January 6, 2010
Copyright
Copyright © 2007–2010 Texas Instruments, Inc. All rights reserved. Stellaris and StellarisWare are registered trademarks of Texas 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.
Texas Instruments
108 Wild Basin, Suite 350
Austin, TX 78746
http://www.ti.com/stellaris

Stellaris® LM3S1968 Evaluation Board
January 6, 2010 3
Table of Contents
Chapter 1: Stellaris® LM3S1968 Evaluation Board .......................................................................................7
Features..............................................................................................................................................................8
Block Diagram ....................................................................................................................................................8
Evaluation Kit Contents ......................................................................................................................................9
Evaluation Board Specifications .....................................................................................................................9
Features of the LM3S1968 Microcontroller.........................................................................................................9
Chapter 2: Hardware Description..................................................................................................................11
LM3S1968 Evaluation Board............................................................................................................................11
LM3S1968 Microcontroller Overview............................................................................................................11
Hibernation Module.......................................................................................................................................11
Clocking........................................................................................................................................................11
Reset.............................................................................................................................................................11
Power Supplies.............................................................................................................................................12
Debugging.....................................................................................................................................................12
USB Device Controller Functions .....................................................................................................................13
USB Overview...............................................................................................................................................13
USB to JTAG/SWD.......................................................................................................................................13
Virtual COM Port...........................................................................................................................................13
Serial Wire Out..............................................................................................................................................14
Organic LED Display ........................................................................................................................................14
Virt(ual CO)-5.8(M Port)-78.1(.)-5.8(...)-5.8(...(...)-5.8(...)-5.8(....)-5.8(...)-5.8()-5.7(...)3-34...)-5.8(....)-5.8(...)-5.8(...)-Design Guidelin............................................................

4January 6, 2010
List of Tables
Table 2-1. Stellaris LM3S1968 Evaluation Board Hardware Debugging Configurations................................12
Table 2-2. Isolating On-Board Hardware........................................................................................................15
Table B-1. I/O Breakout Pads.........................................................................................................................27
Table B-2. Recommended Connectors...........................................................................................................28
Table B-3. 20-Pin JTAG/SWD Configuration..................................................................................................28

Stellaris® LM3S1968 Evaluation Board
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List of Figures
Figure 1-1. Stellaris LM3S1968 Evaluation Board Layout.................................................................................7
Figure 1-2. LM3S1968 Evaluation Board Block Diagram ..................................................................................8
Figure 2-1. ICD Interface Mode .......................................................................................................................16
Figure B-1. Component Locations ...................................................................................................................25
Figure B-2. LM3S1968 Evaluation Board Dimensions.....................................................................................26

6January 6, 2010

January 6, 2010 7
Stellaris® LM3S1968 Evaluation Board
The Stellaris® LM3S1968 Evaluation Board is a compact and versatile evaluation platform for the
Stellaris LM3S1968 ARM® Cortex™-M3-based microcontroller. The evaluation kit design
highlights the LM3S1968 microcontroller's peripherals and its Hibernation module.
A 3V lithium battery, included in the kit, supplies power to the Hibernation module and maintains
data and real-time clock information for about two years in the absence of USB power.
You can use the EVB either as an evaluation platform or as a low-cost in-circuit debug interface
(ICDI). In debug interface mode, the on-board microcontroller is disabled, allowing connection of
the debug signals to an external Stellaris microcontroller target. The kit is also compatible with
high-performance external JTAG debuggers.
This evaluation kit enables quick evaluation, prototype development, and creation of
application-specific designs using the LM3S1968's broad range of peripherals. The kit also
includes extensive source-code examples, allowing you to start building C code applications
quickly.
Figure 1-1. Stellaris LM3S1968 Evaluation Board Layout
USB Device
Interface
Lithium coin cell
66 pin I/O break-out
header
Navigation
Switches
Select switch
Status LEDs
Speaker
Reset switch
Power LED
OLED Graphics
Display
JTAG/SWD input and output
Stellaris
TM
LM3S1968
Microcontroller
In-circuit Debug
Interface
Hibernate LED

Stellaris® LM3S1968 Evaluation Board
8January 6, 2010
Features
The Stellaris LM3S1968 Evaluation Kit includes the following features:
Stellaris LM3S1968 microcontroller
Simple setup; USB cable provides serial communication, debugging, and power
OLED graphics display with 128 x 96 pixel resolution
User LED, navigation switches, and select pushbuttons
8Ωmagnetic speaker with class D amplifier
Internal 3 V battery and support for on-chip hibernation module
USB interface for debugging and power supply
Standard ARM® 20-pin JTAG debug connector with input and output modes
LM3S1968 I/O available on labeled break-out pads
Block Diagram
Figure 1-2. LM3S1968 Evaluation Board Block Diagram
USB
Stellaris
LM3S1968
Microcontroller

Stellaris® LM3S1968 Evaluation Board
January 6, 2010 9
Evaluation Kit Contents
The evaluation kit contains everything needed to develop and run applications for Stellaris
microcontrollers including:
LM3S1968 evaluation board (EVB)
USB cable
20-pin JTAG/SWD target cable
CD containing:
–A supported version of one of the following (including a toolchain-specific Quickstart
guide):
• Keil™ RealView® Microcontroller Development Kit (MDK-ARM)
• IAR Embedded Workbench
• Code Sourcery GCC development tools
• Code Red Technologies development tools
• Texas Instruments’ Code Composer Studio™ IDE
–Complete documentation
–Quickstart application source code
–Stellaris® Firmware Development Package with example source code
Evaluation Board Specifications
Board supply voltage: 4.37–5.25 Vdc from USB connector


Stellaris® LM3S1968 Evaluation Board
10 January 6, 2010
Eight 10-bit ADC channels (inputs) when used as single-ended inputs
Three independent integrated analog comparators
Two I2C modules
Three PWM generator blocks
–One 16-bit counter
–Two comparators
–Produces two independent PWM signals
–One dead-band generator
Two QEI modules with position integrator for tracking encoder position
5 to 52 GPIOs, depending on user configuration
On-chip low drop-out (LDO) voltage regulator
Hibernation module

January 6, 2010 11
Hardware Description
In addition to a microcontroller, the Stellaris LM3S1968 evaluation board includes a range of useful
peripherals and an integrated in-circuit debug interface (ICDI). This chapter describes how these
peripherals operate and interface to the microcontroller.
LM3S1968 Evaluation Board
LM3S1968 Microcontroller Overview
The heart of the EVB is a Stellaris LM3S1968 ARM Cortex-M3-based microcontroller. The
LM3S1968 offers 256-KB Flash memory, 50-MHz operation, and a wide range of peripherals.
Refer to the LM3S1968 data sheet (order number DS-LM3S1968) for complete device details.
The LM3S1968 microcontroller is factory programmed with a quickstart demo program. The
quickstart program resides in the LM3S1968 on-chip Flash memory and runs each time power is
applied unless the quickstart has been replaced with a user program.
Hibernation Module
The Hibernation Module manages removal and restoration of power to the microcontroller and
peripherals while maintaining a real-time clock (RTC) and non-volatile memory. The EVB includes
a 3 V Lithium battery to maintain Hibernate module power when USB power is unavailable.

Hardware Description
12 January 6, 2010
Internal debug mode—By the USB device controller (U5 FT2232) when instructed by
debugger
The LM3S1968 microcontroller has an internal power-on reset, so the external circuits used in the
EVB are not required in typical applications.
Power Supplies
In normal operating mode, the LM3S1968 is powered from a +3.3-V supply. A low drop-out (LDO)
regulator converts +5-V power from the USB cable to +3.3-V. +3.3-V power is available for
powering external circuits.
If +5-V is removed, the Hibernation module will remain powered by the 3-V lithium battery. Other
microcontroller and board functions will not function until power is restored.

Hardware Description
14 January 6, 2010
Serial Wire Out
The evaluation board supports the Cortex-M3 serial-wire output (SWO) trace capabilities. Under
debugger control, the CPLD can route the SWO datastream to the virtual communication port
(VCP) transmit channel. The debugger can then decode and interpret the trace information
received from the VCP. The normal VCP connection to UART0 is interrupted when using SWO. Not
all debuggers support SWO. Refer to the Stellaris LM3S3748 data sheet for additional information
on the trace port interface unit (TPIU).
Organic LED Display
The EVB features an Organic LED (OLED) graphics display with 128 x 96 pixel resolution. OLED
is a new technology that offers many advantages over LCD display technology. The display is
protected during shipping by a thin, protective plastic film. The film can be removed using a pair of
tweezers.
Features
RiT Display P14201 series display
128 columns by 96 rows
High-contrast (typ. 500:1)
Excellent brightness (120 cd/m2)
Fast 10 us response
Control Interface
The OLED display has a built-in controller IC with synchronous serial and parallel interfaces.
Synchronous serial (SSI) is used on the EVB as it requires fewer microcontroller pins. Data cannot
be read from the OLED controller; only one data line is necessary. The Stellaris® Firmware
Development Package (included on the Documentation and Software CD) contains complete
drivers with source-code for the OLED display.
Power Supply
A +15-V supply is needed to bias the OLED display. A FAN5331 device from Fairchild combines
with a few external components to complete a boost converter. A GPIO (PH3/FAULT) is assigned
to turn on and off the controller as necessary for power rail sequencing. When the OLED display is
operating, a small amount of power can be drawn from the +15-V supply to power other devices.
Design Guidelines
The OLED display has a lifetime of about 13,000 hours. It is also prone to degradation due to
burn-in, similar to CRT and plasma displays. The quickstart application includes both a screen
saver and a power-down mode to extend display life. These factors should be considered when
developing EVB applications that use the OLED display.
Further Reference
For additional information on the RiT OLED display, visit www.ritekdisplay.com.

Stellaris® LM3S1968 Evaluation Board
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Other Peripherals
Speaker
The LM3S1968 evaluation board's speaker circuit can be used in either tone or waveform mode.
The quick-start application uses tone mode.
In tone mode, the LM3S1968 microcontroller's PWM module directly generates tones within the
audible frequency range. The width of the pulses determines the volume. If only one PWM signal
(PWM2 or PWM3) is used, the non-PWM signal should be configured as a general-purpose
output. For increased speaker volume, PWM2 and PWM3 can be configured as complementary
drive signals. In tone mode, be careful to avoid large DC currents in the speaker.
Waveform mode uses two high-frequency PWM signals to drive a MOSFET H-bridge with an
output filter. This circuit is essentially a Class-D amplifier. The symmetrical 2nd order low-pass L-C
filter has a cut-off frequency of approximately 33 kHz. The microcontroller's PWM module should
be configured with a PWM frequency of at least 100 kHz. Using 500 kHz improves audio quality

Hardware Description
16 January 6, 2010
Interfacing to the EVB
An array of accessible I/O signals makes it easy to interface the EVB to external circuits. All
LM3S1968 I/O lines (except those with both JTAG and SWD functions) are brought out to 0.1”
pitch pads. For quick reference, silk-screened labels on the PCB show primary pin functions.
Table B-2 on page 28 has a complete list of I/O signals as well as recommended connectors.
Most LM3S1968 I/O signals are +5-V tolerant. Refer to the LM3S1968 data sheet for detailed
electrical specifications.
Using the In-Circuit Debugger Interface
The Stellaris LM3S1968 Evaluation Kit can operate as an In-Circuit Debugger Interface (ICDI).
ICDI acts as a USB to the JTAG/SWD adaptor, allowing debugging of any external target board
that uses a Stellaris microcontroller. See “Debugging Modes” on page 12 for a description of how
to enter Debug Out mode.
Figure 2-1. ICD Interface Mode
Pin 29 PA3/SSI0FSS OLED display chip select JP5
Pin 37 PG6/PHA1 Right switch JP6
Pin 36 PG7/PHB1 Select switch JP7
Pin 40 PG5 Left switch JP8
Pin 41 PG4 Down switch JP9
Pin 31 PA5/SSI0TX OLED display data in JP10
Pin 28 PA2/SSI0CLK OLED display clock JP11
Pin 34 PA6/I2C1SCL OLED display data/control select JP12
Pin 27 PA1/U0TX Virtual COM port transmit JP13
Pin 86 PH0/PWM2 Sound+ JP14
Pin 85 PH1/PWM3 Sound- JP15
Table 2-2. Isolating On-Board Hardware (Continued)
Microcontroller Pin Microcontroller Assignment To Isolate, Remove...
Evaluation Board Target
Board
Stellaris
MCU
Target
Cable
`

Stellaris® LM3S1968 Evaluation Board
January 6, 2010 17
The debug interface operates in either serial-wire debug (SWD) or full JTAG mode, depending on
the configuration in the debugger IDE.
The IDE/debugger does not distinguish between the on-EVB Stellaris microcontroller and an
external Stellaris microcontroller. The only requirement is that the correct Stellaris device is
selected in the project configuration.

Hardware Description
18 January 6, 2010

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Schematics
This section contains the schematics for the LM3S1968 Evaluation Board:
LM3S1968 Microcontroller on page 20
OLED Display, Switches and Audio on page 21
USB and Debugger Interfaces on page 22
USB, Debugger Interfaces and Power on page 23
JTAG Logic with Auto Mode Detect and Hibernate on page 24
APPENDIX A

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A A
Document Number:
RevSheetDate: of
3/4/2008 1 4
Drawing Title:
Page Title:
Size
Stellaris LM3S1968 Evaluation Board
LM3S1968 Microcontroller
B
B
EK-LM3S1968
Revision Date Description
0 8/9/07 Final prototype release
History
INT_TCK
TMS/SWDIO
PC2/TDI
PC3/TDO/SWO
ADC3
ADC2
ADC1
ADC0