Hardware Description
August 29, 2012
13
Connectors J1 and J2 of the Stellaris® LM4F120 LaunchPad BoosterPack XL Interface provide
compatibility with MSP430™ LaunchPad BoosterPacks. Highlighted functions in Table 2-3, "J1
Connector" on page 11 and Table 2-4, "J2 Connector" on page 11 indicate configuration for
compatibility with the MSP430 LaunchPad.
A complete list of Stellaris® BoosterPacks and Stellaris LaunchPad-compatible MSP430
BoosterPacks is available at
www.ti.com/stellaris-launchpad
.
Power Management (Schematic on page 19)
Power Supplies
The Stellaris® LaunchPad can be powered from one of two power sources:
On-board Stellaris® In-Circuit Debug Interface (ICDI) USB cable (Debug, Default)
USB Device cable (Device)
The POWER SELECT switch (SW3) is used to select one of the two power sources. Select only
one source at a time.
Hibernate
The Stellaris® LaunchPad provides an external 32.768 kHz crystal (Y1) as the clock source for the
LM4F120H5QR’s Hibernation module clock source. The current draw while in Hibernate mode can
be measured by making some minor adjustments to the Stellaris® LaunchPad. This is explained in
more detail later in this section.
The conditions that can generate a wake signal to the Hibernate module on the Stellaris®
LaunchPad are waking on a Real-time Clock (RTC) match and/or waking on assertion of the
WAKE
pin.
1
The second user switch (SW2) is connected to the
WAKE
pin on the microcontroller. The
WAKE
pin, as well as the V
DD
and HIB pins, are easily accessible through breakout pads on the
Stellaris® LaunchPad. See Appendix A, “Schematics” on page 22 for details.
There is no external battery source on the Stellaris® LaunchPad Hibernation module, which
means the VDD3ON power control mechanism should be used. This mechanism uses internal
switches to remove power from the Cortex-M4F processor as well as to most analog and digital
functions while retaining I/O pin power.
To measure the Hibernation mode current or the Run mode current, the V
DD
jumper that connects
the 3.3 V pin and the MCU_PWR pin must be removed. See Appendix A, “Schematics” on
page 17 for details on these pins and component locations. An ammeter should then be placed
between the 3.3 V pin and the MCU_PWR pin to measure I
DD
(or I
HIB_VDD3ON
). The
LM4F120H5QR microcontroller uses V
DD
as its power source during V
DD3ON
Hibernation mode,
so I
DD
is the Hibernation mode (VDD3ON mode) current. This measurement can also be taken
during Run mode, which measures I
DD
the microcontroller running current.
Clocking
The Stellaris® LaunchPad uses a 16.0-MHz crystal (Y2) to complete the LM4F120H5QR
microcontroller's main internal clock circuit. An internal PLL, configured in software, multiples this
clock to higher frequencies for core and peripheral timing.
The Hibernation module is clocked from an external 32.768 kHz crystal (Y1).
1. If the board does not turn on when you connect it to a power source, the microcontroller might be in Hibernate mode (depending
on the programmed application). You must satisfy one of the programmed wake conditions and connect the power to bring the
microcontroller out of Hibernate mode and turn on the board.