Texas Instruments BoosterPack BOOSTXL-RS232 User manual

BOOSTXL-RS232 BoosterPack™ Hardware
User's Guide
Literature Number: SLLU250
November 2016

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Table of Contents
Contents
1 Trademarks......................................................................................................................... 4
2 Introduction......................................................................................................................... 4
2.1 Overview .................................................................................................................. 4
3 Hardware Description........................................................................................................... 5
3.1 Top and Bottom View.................................................................................................... 5
3.2 Board Overview .......................................................................................................... 5
3.3 Block Diagram............................................................................................................ 6
3.4 DB9 Connector ........................................................................................................... 7
3.5 Header Descriptions..................................................................................................... 8
3.6 LED Description......................................................................................................... 10
4 Functional Modes............................................................................................................... 11
4.1 Auto-Powerdown Plus.................................................................................................. 11
4.2 Forced On ............................................................................................................... 11
4.3 Forced Off ............................................................................................................... 11
4.4 Invalid .................................................................................................................... 12
5 Interfacing with External Hardware....................................................................................... 13
6 Additional Information ........................................................................................................ 14
6.1 Design Files ............................................................................................................. 14
6.2 Hardware Change Log................................................................................................. 14
6.3 Schematic................................................................................................................ 14
6.4 PCB Layout.............................................................................................................. 15

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List of Figures
List of Figures
1 BOOSTXL-RS232 ........................................................................................................... 4
2 Top View of BOOSTXL-RS232 ............................................................................................ 5
3 Bottom View of BOOSTXL-RS232 ........................................................................................ 5
4 BOOSTXL-RS232 Overview ............................................................................................... 5
5 BOOSTXL-RS232 Block Diagram......................................................................................... 6
6 DB9 Pinout.................................................................................................................... 7
7 GPIO Headers................................................................................................................ 8
8 Header J9..................................................................................................................... 9
9 Supply Select................................................................................................................. 9
10 RS232 LEDs ................................................................................................................ 10
11 Interfacing With LaunchPad............................................................................................... 13
12 BOOSTXL-RS232 Schematic (Zoom for Higher Resolution)......................................................... 14
13 Top Layer Routing ......................................................................................................... 15
14 Bottom Layer Routing...................................................................................................... 15
List of Tables
1 RS-232 Female DB9 Connector Pin Summary.......................................................................... 7
2 Driver Functions............................................................................................................ 11
3 Receiver Functions......................................................................................................... 11
4 INVALID Status............................................................................................................. 12
5 Description of Hardware Changes ....................................................................................... 14

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BOOSTXL-RS232 BoosterPack™ Hardware
User's Guide
SLLU250–November 2016
BOOSTXL-RS232 BoosterPack™ Hardware
1 Trademarks
BoosterPack, LaunchPad are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
2 Introduction
2.1 Overview
The RS232 BoosterPack provides the opportunity to communicate to and from a TI LaunchPad™ using
the RS232 serial protocol. This opens new capabilities for the microcontrollers to interface with industrial
equipment for debugging, for accessing memory directly for backup recovery, and for simplified data
transfer between systems with proprietary code.
The featured product is the TRS3122E, an ultra-low power, high-speed dual RS232 transceiver. It
supports data [RX, TX] channels as well as flow control [RTS, CTS] channels that can be easily assigned
to 1 of 10 general purpose input/output (GPIO) pins. These channels on the TRS3122E can be configured
to be either one set of data channels and one set of control channels for flow control or to be two sets of
data channels. However, this BoosterPack is configured for one set of data channels [RX, TX] and one set
of control channels [RTS, CTS]. With its unique doubler and tripler charge pump architecture, the
TRS3122E can operate at a VCC as low as 1.8 V while maintaining compatibility with 3.3-V and 5-V
supplies. This BoosterPack allows for operating voltages of 1.8 V or 3.3 V.
This device features a shutdown mode that reduces supply current as low as 0.5 µA. This can be done
manually or by setting the TRS3122E into its Auto-Powerdown Plus mode. See Section 4 for more
information on the modes of operation of the TRS3122E along with how to set up the BoosterPack for
these modes.
2.1.1 What Is Included?
• 1× RS232 BoosterPack
• 7× Shunt Jumper
Figure 1 is a photo of the BOOSTXL-RS232 board.
Figure 1. BOOSTXL-RS232

Female DB9 Connector
Green/Red
LEDs for RX1 &
RTS1
Green/Red
LEDs for TX1
& CTS1
TRS3122E
RS232
Transceiver
LP2985-18 LDO
& J12 Header for
VCC Select
J9 Header for
FORCEON,
FORCEOFF, &
INVALID Selects
J1, J3 Standard BoosterPack
Headers
J7, J8 GPIO Select Headers
J4, J2 Standard BoosterPack
Headers
J5, J6 GPIO Select Headers
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BOOSTXL-RS232 BoosterPack™ Hardware
3 Hardware Description
3.1 Top and Bottom View
Figure 2 is a top view of the BOOSTXL-RS232 and Figure 3 is a bottom view of the BOOSTXL-RS232.
Figure 2. Top View of BOOSTXL-RS232 Figure 3. Bottom View of BOOSTXL-RS232
3.2 Board Overview
Figure 4 shows an overview of the BOOSTXL-RS232 BoosterPack. The main features such as devices,
connectors, headers, and LEDs are highlighted.
See Section 3.4,Section 3.5, and Section 3.6 for additional details regarding each portion of the board.
Figure 4. BOOSTXL-RS232 Overview

40-Pin
BoosterPackTM
Interface
LP2985-18
GND GND
3-Pin Vcc
Select
2 × 30-Pin GPIO
Select
GND
6-Pin Functional
Mode/Invalid
Select
LaunchPadTM BOOSTXL-RS232
3V3
1V8
Vcc
RX1
RTS1
TX1
CTS1
GPIO
GPIO
GPIO
GPIO
FORCEON
FORCEOFF
INVALID
LaunchPad TRS3122E
GPIO
GPIO
GPIO
Female
DB9
GND
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BOOSTXL-RS232 BoosterPack™ Hardware
3.3 Block Diagram
Figure 5 details a block diagram of the BOOSTXL-RS232 BoosterPack. The 40-pin BoosterPack header
allows the BoosterPack to be easily interfaced with LaunchPads. A 3-pin header is available to change
VCC/VLbetween 3.3 V and 1.8 V. This allows the BoosterPack to communicate with LaunchPads either at
3.3-V or 1.8-V logic levels. See Section 3.5.4 for more details. The two 30-pin GPIO headers allow for the
selection of GPIO pins on the LaunchPad to be connected to the TRS3122E. See Section 3.5.1 for more
information. A 6-pin header is available to allow for the FORCEON, FORCEOFF, and INVALID pins on the
TRS3122E to be connected to LaunchPad GPIO pins for more control. See Section 3.5.2 and
Section 3.5.3 for more information.
Figure 5. BOOSTXL-RS232 Block Diagram

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BOOSTXL-RS232 BoosterPack™ Hardware
3.4 DB9 Connector
The BoosterPack includes a female data circuit-terminating equipment (DCE) DB9 port. Female DCE
ports are designed to connect with the male data terminal equipment (DTE) port of the computer. The
labeling for Figure 6 is from the perspective of the computer with the DTE port. Therefore, RX1 is actually
an output from the BoosterPack to the connected device through the RS232 interface, while TX1 is an
input from the connected device to the BoosterPack through the RS232 interface. The same applies to the
RTS1 (input) and CTS1 (output) ports. The RX2, TX2, CTS2, and RTS2 ports are used to interface with
the microcontroller through 0-V to 3.3-V (or 1.8-V) TTL signals. See Table 1 for information on how the
DB9 connector is routed on the BOOSTXL-RS232 BoosterPack.
Figure 6. DB9 Pinout
Table 1. RS-232 Female DB9 Connector Pin Summary
Pin Function
1 NC
2 UART Receive 1 (RX1)
3 UART Transmit 1 (TX1)
4 Shorted to pin 6 (unused flow control line)
5 GND
6 Shorted to pin 4 (unused flow control line)
7 Request to Send 1 (RTS1)
8 Clear to Send 1 (CTS1)
9 NC

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3.5 Header Descriptions
3.5.1 Using J5, J6 and J7, J8 GPIO Headers
The J5, J6 and J7, J8 10 × 3 headers are for assigning the TRS3122E UART Drivers or Receivers
(labeled as CTS2, RX2, RTS2, and TX2 on the BoosterPack) to various LaunchPad GPIOs. The default
jumper setup has TX2, RX2, RTS2, and CTS2 assigned to LaunchPad GPIO pins GP3, GP4, GP5, and
GP8, respectively. TI recommends tying TX2 and RX2 to GP3 and GP4, respectively, since GP3 and GP4
are typically the UART transmit and receive ports on TI LaunchPads, this is not required but should be
kept in mind. RTS2 and CTS2 can be connected to any desired GPIO pin.
Each pin of the middle column of the 10 × 3 headers correlates to a particular GPIO pin. The pin it is
connected to is labeled in between the J5, J6 and J7, J8 header groups, this is seen in Figure 7. The
columns on either side of the middle column are connected to their coinciding transceiver pins, which are
labeled at the bottom of each column, this is seen in Figure 7. For example, looking at header J5, J6 in
Figure 7, the right column coincides with RX2. Placing a jumper across the first pins of the middle column
and the right column would short GP3 from the LaunchPad to the DIN1 pin on the TRS3122E.
NOTE: See Section 5 for information on headers J1-4 and how they interface with the LaunchPad
ecosystem.
NOTE: See Figure 13 and Figure 14 for more clarification of how the headers are routed.
Figure 7. GPIO Headers
3.5.2 Utilizing FORCEON and FORCEOFF
The J9 3 × 2 header allows for the option to assign FORCEON and FORCEOFF to GP19 and GP18,
respectively. FORCEON can be connected to GP19 by placing a jumper across pins 1 and 2 on J9 and
FORCEOFF can be connected to GP18 by placing a jumper across pins 3 and 4 on J9, see Figure 8. This
allows for the control of the different functional modes of the TRS3122E. See Section 4 to learn more
about the different functional modes and how to control them using FORCEON and FORCEOFF.
NOTE: If FORCEON and FORCEOFF are not intended to be controlled, then remove the jumpers
discussed.

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BOOSTXL-RS232 BoosterPack™ Hardware
Figure 8. Header J9
3.5.3 Utilizing INVALID Signal
The J9 3 × 2 header also allows for the option to monitor the INVALID pin of the TRS3122E by linking it to
a GPIO pin on a LaunchPad. By placing a jumper across pins 5 and 6 on J9, see Figure 8, the INVALID
pin will be connected to GP14. The GPIO port on a LaunchPad can then be set to an input and used to
monitor the INVALID pin. See Section 4.4 to learn more about the INVALID pin.
NOTE: If the INVALID pin is not intended to be monitored, remove the jumper.
3.5.4 Assigning Desired Supply Voltage
The BOOSTXL-RS232 BoosterPack is populated with a linear regulator to drop the typical 3.3-V VCC on
most LaunchPads to 1.8 V. This allows for communication with LaunchPads that are capable of
communicating at 1.8-V logic levels. To switch between a 1.8-V and 3.3-V supply, use a jumper on J12 to
short the center VCC pin to the desired supply voltage, see Figure 9. A short between pin 1 and 2 results in
3.3-V VCC and a short between 2 and 3 results in 1.8-V VCC. Pin 1 on J12 is denoted with a white line
along one edge of the pin, as seen in Figure 9. While VLand VCC are independent on the TRS3122E
device itself, these two pins are tied together on the BoosterPack. This way VLcannot accidentally be set
higher than VCC. This option was added to display the ultra-low voltage capabilities of the TRS3122E.
NOTE: VCC and VLshould only be set to 1.8 V if the BOOSTXL-RS232 is intended to interface with a
LaunchPad that operates at 1.8-V logic levels. Otherwise TI recommends leaving the jumper
across pins 1 and 2 of J12.
Figure 9. Supply Select

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BOOSTXL-RS232 BoosterPack™ Hardware
3.6 LED Description
For this BoosterPack, there are two LEDs per RS232 line (RTS1, RX1, CTS1, TX1) and one power
indication LED, see Figure 10. The LEDs serve as a reference when connecting the BoosterPack to a
LaunchPad and up to a RS232 serial port. A red LED for an RS232 line indicates negative voltage or a
LOW signal, while a green LED indicates positive voltage or a HIGH signal. This information is also
denoted next to each LED; a '+' sign for the green LED and a '-' sign for the red LED. Upon powering the
BoosterPack, the power LED will turn on and the driver and receiver line LEDs may also be on, depending
on what the board is connected to.
Since RS232 TX and RX lines sit at a LOW voltage level until data is transmitted or received, the red LED
for TX1 and RX1 on the board will be on until data is transmitted or received. While transmitting or
receiving, the green LED will blink for the line in use. End of transmission is indicated with just a red LED.
The RTS1 green LED will be on when a request-to-send signal is raised and the CTS1 green LED will be
on when the clear-to-send signal is raised. Otherwise, the red LEDs will be on.
Figure 10. RS232 LEDs