LM3S9B81 Datasheet, PDF (201/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Stellaris® LM3S9B81 Microcontroller
7.2.2.2
7.2.2.3
ROM checks address 0x000.0004 to see if the Flash memory has a valid reset vector. If the data
at address 0x0000.0004 is 0xFFFF.FFFF, then it is assumed that the Flash memory has not yet
been programmed, and the core executes the ROM Boot Loader.
The boot loader uses a simple packet interface to provide synchronous communication with the
device. The speed of the boot loader is determined by the internal oscillator (PIOSC) frequency as
it does not enable the PLL. The following serial interfaces can be used:
■ UART0
■ SSI0
■ I²C0
■ Ethernet
For simplicity, both the data format and communication protocol are identical for all serial interfaces.
Note: The Flash-memory-resident version of the Boot Loader also supports CAN and USB.
See the Stellaris® Boot Loader User's Guide for information on the boot loader software.
Stellaris^® Peripheral Driver Library
The Stellaris^® Peripheral Driver Library contains a file called driverlib/rom.h that assists with
calling the peripheral driver library functions in the ROM. The detailed description of each function
is available in the Stellaris® ROM User’s Guide. See the "Using the ROM" chapter of the Stellaris®
Peripheral Driver Library User's Guide for more details on calling the ROM functions and using
driverlib/rom.h.
A table at the beginning of the ROM points to the entry points for the APIs that are provided in the
ROM. Accessing the API through these tables provides scalability; while the API locations may
change in future versions of the ROM, the API tables will not. The tables are split into two levels;
the main table contains one pointer per peripheral which points to a secondary table that contains
one pointer per API that is associated with that peripheral. The main table is located at 0x0100.0010,
right after the Cortex-M3 vector table in the ROM.
DriverLib functions are described in detail in the Stellaris® Peripheral Driver Library User's Guide.
Additional APIs are available for graphics and USB functions, but are not preloaded into ROM. The
Stellaris^® Graphics Library provides a set of graphics primitives and a widget set for creating graphical
user interfaces on Stellaris^® microcontroller-based boards that have a graphical display (for more
information, see the Stellaris® Graphics Library User's Guide). The Stellaris^® USB Library is a set
of data types and functions for creating USB Device, Host or On-The-Go (OTG) applications on
Stellaris microcontroller-based boards (for more information, see the Stellaris® USB Library User's
Guide).
Advanced Encryption Standard (AES) Cryptography Tables
AES is a strong encryption method with reasonable performance and size. AES is fast in both
hardware and software, is fairly easy to implement, and requires little memory. AES is ideal for
applications that can use pre-arranged keys, such as setup during manufacturing or configuration.
Four data tables used by the XySSL AES implementation are provided in the ROM. The first is the
forward S-box substitution table, the second is the reverse S-box substitution table, the third is the
forward polynomial table, and the final is the reverse polynomial table. See the Stellaris® ROM
User’s Guide for more information on AES.
June 29, 2010
201
Texas Instruments-Advance Information