Hardware
14
SLAU678A – March 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
MSP430FR5994 LaunchPad™ Development Kit (MSP
‑
EXP430FR5994)
2.3.3.3
Disabling the Super Cap
The super cap can be completely decoupled from the board by removing the J8 jumper. Hang this jumper
off only one pin to prevent losing the jumper.
2.4
Measure MSP430 Current Draw
To measure the current draw of the MSP430FR5994 using a multimeter, use the 3V3 jumper on the J101
jumper isolation block. The current measured includes the target device and any current drawn through
the BoosterPack plug-in module headers.
To measure ultra-low power, follow these steps:
•
Remove the 3V3 jumper in the J101 isolation block, and attach an ammeter across this jumper.
•
Consider the effect that the backchannel UART and any circuitry attached to the MSP430FR5994 may
have on current draw. Consider disconnecting these at the isolation jumper block, or at least consider
their current sinking and sourcing capability in the final measurement.
•
Make sure there are no floating inputs or outputs (I/Os) on the MSP430FR5994. These cause
unnecessary extra current draw. Every I/O should either be driven out or, if it is an input, should be
pulled or driven to a high or low level.
•
Begin target execution.
•
Measure the current. Keep in mind that if the current levels are fluctuating, it may be difficult to get a
stable measurement. It is easier to measure quiescent states.
Alternatively, Ener+ technology can be used to measure the same current, and see energy
profiles through integrated GUI in CCS and IAR. EnergyTrace allows you to compare various current
profiles and better optimize the energy performance.
2.5
Clocking
The MSP-EXP430FR5994 provides external clocks in addition to the internal clocks in the device.
•
Q1: 32-kHz Epson crystal (FC-135R)
•
Q2: DNP high-frequency crystal footprint
The 32-kHz crystal allows for lower LPM3 sleep currents than do the other low-frequency clock sources.
Therefore, the presence of the crystal allows the full range of low-power modes to be used.
The high-frequency crystal is not populated by default, but the footprint for a crystal is provided. Populate
a high-frequency crystal for applications that need more precise high-frequency clock sources than the
internal DCO.
The internal clocks in the device default to the following configuration:
•
MCLK: DCO 1 MHz
•
SMCLK: DCO 1 MHz
•
ACLK: REFO 32.768 kHz
For more information about configuring internal clocks and using the external oscillators, see the
MSP430FR58xx, MSP430FR59xx, MSP430FR68xx, and MSP430FR69xx Family User's Guide
2.6
Using the eZ-FET Debug Probe With a Different Target
The eZ-FET debug probe on the LaunchPad development kit can interface to most MSP430 derivative
devices, not just the onboard MSP430FR5994 target device.
To do this, disconnect every jumper in the isolation jumper block. This is necessary, because the debug
probe cannot connect to more than one target at a time over the Spy-Bi-Wire (SBW) connection.
Next, make sure the target board has proper connections for SBW. Note that to be compatible with SBW,
the capacitor on RST/SBWTDIO cannot be greater than 2.2 nF. The documentation for designing MSP430
JTAG interface circuitry is the
MSP430 Hardware Tools User's Guide
Finally, wire together these signals from the debug probe side of the isolation jumper block to the target
hardware:
