Main Board
www.ti.com
2.3 Target Circuit
This section describes the parts in the target circuit that is used for application development on
MSP430FR6989.
2.3.1 LED
LED1 and LED2 are connected to PJ.2 and PJ.3 of the MSP430FR6989 respectively. Turn on the LED by
output low to the corresponding pin.
Those two pins can be released as GPIOs by removing the jumpers on JP13 and JP14
2.3.2 LCD
A LCD screen is connected to the MSP430FR6989 for displaying information. The LCD is a 160-segment
display using 40 segment pins and 4 MUX pins. On this EVM board, the LCD uses S0 to S21 and S26 to
S43 of the MSP430FR6989. By default, the board uses a capacitor charge pump to provide the LCD
voltage. For lower power consumption, it is also possible to use an external resistor ladder by replacing
the charge pump capacitor.
Table 4. LCD Voltage Generator Configuration
Charge Pump (Default) External Resistor Ladder
VR1, R11, R12, R13 Not used R11, R12, R13 330K
C33 4.7 µF, 10 V For contrast adjustment
VR1 (for example, 200K)
C33 Not used
2.3.3 Oscillator Circuit
The MSP430FR6989 consists of an internal DCO and a low-frequency oscillator to provide clock for the
MCU. The clock can also be provided by low-frequency clock or high-frequency clock externally. X1 is for
a low-frequency oscillator, typically a 32.768-kHz crystal. X2 is for a high-frequency oscillator with a
maximum frequency of 16 MHz. C10 and C11 are the load capacitors for X1, and C12 and C13 are the
load capacitors for X2. The capacitor value depends on the characteristic of the crystals.
The oscillator pins of the MSP430FR6989 are Port J (PJ.4 and PJ.5 for LFXTL, PJ.6 and PJ.7 for HFXTL)
and disconnected to the GPIO pool by default. If oscillators are not used, those four pins can be released
for general use by shorting R59 and R60 (LFXTL) or R61 and R62 (HFXTL).
2.3.4 4-Way With Select Navigation Switch
The board provides a 4-way with select navigation switch. The switch is connected to the ADC input pin
(P1.2/A2) of the MSP430FR6989. The switch is connected using a resistor ladder. The internal ADC and
VREF are used to determine in which direction the button is pressed. To save power, the ADC is not
always on. When it is idle, the pin is set as GPIO and waits for falling edge interrupt. The resistor values of
the resistor ladder are calculated such that each direction of the switch triggers the falling edge interrupt of
the pin. Then the pin is set as ADC and measures the voltage to determine which direction is pressed.
The voltage reference for the ADC is set at 1.2 V by VREF.
2.3.5 RF Connector
The board provides an RF connector for wireless communication. The connector is compatible with TI’s
wireless EM modules. Refer to specific EM modules for device-specific information. The SPI of the EM
module utilizes UCA1 of the MSP430FR6989 while the UART and the alternate SPI utilizes UCA0.
Table 5 shows the pin mapping. Note that not all of the GPIOs are connected. All of the GPIO pins and
communication ports of the RF connectors are connected to the MSP430FR6989 using resistors, and they
can be released for general use by removing the corresponding resistors.
10 EVM430-FR6989 Evaluation Kit SLAU611–January 2015
Submit Documentation Feedback
Copyright © 2015, Texas Instruments Incorporated
