Hardware
11
SLAU678A – March 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
MSP430FR5994 LaunchPad™ Development Kit (MSP
‑
EXP430FR5994)
The backchannel UART is the
MSP Application UART1 (COM13)
port. In this case,
shows
COM13, but this port can vary from one host PC to the next. Identify the correct COM port and configure it
in the host application according to its documentation. Then open the port and begin communication to it
from the host.
On the target MSP430FR5994 side, the backchannel is connected to the eUSCI_A0 module. The eZ-FET
has a configurable baud rate; therefore, it is important that the PC application configures the baud rate to
be the same as what is configured on the eUSCI_A0.
2.2.5
Special Features
2.2.5.1
microSD Card
The MSP430FR5994 LaunchPad development kit features an onboard microSD card. With an SD card,
there is another method of cheap data logging available for users. The Out-Of-Box experience comes with
an SD Card Library that helps users interface the MSP430FR5994 with the SD Card. The library lets users
store data in files with a name of their choice, so that the data can be used later in conjunction with a PC.
The slot can detect if a card is present. If a card is inserted while the MSP430FR5994 is on, an interrupt
for the MCU is generated.
lists the SD Card Detect pin and the rest of the pin assignments that
are used to communicate with the SD card.
Table 3. microSD Card to MSP Connections
microSD Card Function
MSP430FR5994 Pin
SD Card Detect
P7.2
SD SPI MOSI
P1.6
SD SPI MISO
P1.7
SD SPI CS
P4.0
SD SPI CLK
P2.2
R7 on the MSP430FR5994 LaunchPad development kit is not populated on the board to ensure accurate
LPM current measurements. Use the internal MSP pullup resistor in software, or populate R7.
R5 is also not populated. In the SD Card library, the SPI CS line is driven high or low. Often why a pullup
resistor like R5 is included is for during system startup. Before the MSP430FR5994 fully starts and outputs
a high signal on the CS line, it is possible that CS may be floating, and the SD card may interpret other
floating SPI lines as communication. It is a good practice to populate this resistor in an application where
the exact startup conditions are not controlled. For the LaunchPad development kit, this resistor is
removed for precise current measurements when all GPIO are set low.
2.2.5.2
220-mF Super Capacitor
A 220-mF (0.22-F) capacitor is mounted onboard and allows powering the system without any external
power. The super cap can be used in the following ways: charging, using (direct connection to 3V3 rail),
and disconnected. For more details on these use modes and how to use them, see
