January 6, 2010
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Hardware Description
In addition to a microcontroller, the Stellaris LM3S6965 evaluation board includes a range of useful
peripherals and an integrated ICDI. This chapter describes how these peripherals operate and
interface to the MCU.
LM3S6965 Microcontroller
Device Overview
The heart of the EVB is a Stellaris LM3S6965 ARM Cortex-M3-based microcontroller. The
LM3S6965 offers 256 KB Flash memory, 50-MHz operation, an Ethernet controller, and a wide
range of peripherals. Refer to the LM3S6965 data sheet (order number DS-LM3S6965) for
complete device details.
The LM3S6965 microcontroller is factory programmed with a quickstart demo program. The
quickstart program resides in the LM3S6965 on-chip Flash memory and runs each time power is
applied, unless the quickstart has been replaced with a user program.
Ethernet
A key feature of the LM3S6965 microcontroller is its fully integrated Ethernet controller. Only a
RJ45 jack with integrated magnetics and a few passive components are needed to complete the
10/100baseT interface. The RJ45 jack incorporates LEDs that indicate traffic and link status.
These are automatically managed by on-chip microcontroller hardware. Alternatively, the LEDs
can be software controlled by configuring those pins as general-purpose outputs.
The LM3S6965 supports automatic MDI/MDI-X so the EVB can connect directly to a network or to
another Ethernet device without requiring a cross-over cable.
Clocking
The LM3S6965 microcontroller has four on-chip oscillators, three are implemented on the EVB. A
8.0-MHz crystal completes the LM3S6965’s main internal clock circuit. An internal PLL, configured
in software, multiples this clock to 50-MHz for core and peripheral timing.
A small, 25-MHz crystal is used by the LM3S6965 microcontroller for Ethernet physical layer
timing and is independent of the main oscillator.
Reset
The LM3S6965 microcontroller shares its external reset input with the OLED display. In the EVB,
reset sources are gated through the CPLD, though in a typical application a simple wired-OR
arrangement is sufficient.
Reset is asserted (active low) under any one of three conditions:
Power-on reset
Reset push switch SW1 held down
Internal debug mode—By the USB device controller (U4 FT2232) when instructed by
debugger
C H A P T E R 2
Summary of Contents for Stellaris LM3S6965
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