Datasheet
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.
+15-V power is available when the OLED display power supply is active. The speaker and OLED
display boost-converter operate directly from the +5-V power.
Debugging
Stellaris microcontrollers support programming and debugging using either JTAG or SWD. JTAG
uses the signals TCK, TMS, TDI, and TDO. SWD requires fewer signals (SWCLK, SWDIO, and,
optionally, SWO, for trace). The debugger determines which debug protocol is used. For example,
Keil RealView tools support only JTAG debugging.
The JTAG TRST
signal is not required for debugging and is not connected to the 20-pin JTAG/
SWD header. TRST
may be asserted by the CPLD in debug Mode 2.
Debugging Modes
The LM3S1968 evaluation board supports a range of hardware debugging configurations.
Table 2-1 summarizes these configurations.
Modes 2 and 3 automatically detect the presence of an external debug cable. When the
debugger software connected to the EVB's USB controller the EVB automatically selects Mode 2
and illuminates the red Debug Out LED.
Table 2-1. Stellaris LM3S1968 Evaluation Board Hardware Debugging Configurations
Mode Debug Function Use Selected by
1 Internal ICDI Debug on-board LM3S1968
microcontroller over USB
interface.
Default mode
2 ICDI out to JTAG/SWD
header
The EVB is used as a USB to
SWD/JTAG interface to an
external target.
Connecting to an external
target and starting debug
software.
The red Debug Out LED will
be ON.
3 In from JTAG/SWD header For users who prefer an
external debug interface
(ULINK, JLINK, etc.) with the
EVB.
Connecting an external
debugger to the JTAG/SWD
header