Texas Instruments TCA8424 User manual

User's Guide
SCDU004–March 2013
TCA8424 Evaluation Module
This document is the EVM user guide for the TCA8424. The device is a low-voltage keyboard scanner that
can support up to 128 keys, with open drain outputs that can sink up to 12 mA of current for LEDs. The
TCA8424 is fully HID over I2C™ compliant and is available with a pre-programmed keyboard map.
Contents
1 About this Manual ........................................................................................................... 2
2 Information about Cautions and Warnings .............................................................................. 2
3 FCC Warning ................................................................................................................ 2
4 Items Required for Operation ............................................................................................. 3
5 Introduction .................................................................................................................. 3
6 TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions .................................. 4
6.1 TCA8424 EVM Schematic ........................................................................................ 4
6.2 Printed-Circuit Board (PCB) Layout ............................................................................. 5
6.3 Bill of Materials ..................................................................................................... 9
6.4 VCC and GND Connections .................................................................................... 11
6.5 MSP430 Launchpad Interface .................................................................................. 11
6.6 Breakout Pins ..................................................................................................... 12
6.7 LED Outputs ...................................................................................................... 13
7 Launchpad Software Setup .............................................................................................. 14
8 GUI Software Setup ....................................................................................................... 16
9 GUI Walkthrough Guide .................................................................................................. 17
10 Related Documentation ................................................................................................... 30
List of Figures
1 TCA8424 EVM Schematic................................................................................................. 4
2 Layer 1 Top Side: 50-ΩSignal Layer .................................................................................... 5
3 Layer 2 (Int1): Ground Plane.............................................................................................. 6
4 Layer 3 (Int2): 50-ΩSignal with Ground Fill............................................................................. 7
5 Layer 4 Bottom Layer ...................................................................................................... 8
6 VCC and GND Connections ............................................................................................. 11
7 MSP430 Launchpad Interface ........................................................................................... 11
8 Breakout Pins .............................................................................................................. 12
9 LED Outputs ............................................................................................................... 13
List of Tables
1 Bill of Materials.............................................................................................................. 9
2 Header Configurations for P1, P2, and P7............................................................................. 12
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About this Manual www.ti.com
1 About this Manual
This user’s guide describes the TCA8424 Evaluation Module (EVM). This guide contains the EVM
schematics, bill of materials, and top and bottom board layouts.
2 Information about Cautions and Warnings
This section describes the jumpers and connectors on the EVM as well and how to properly connect, set
up, and use the TPS22985EVM.
CAUTION
This EVM contains components that can potentially be damaged by
electrostatic discharge. Always transport and store the EVM in its supplied ESD
bag, when not in use. Handle using an antistatic wristband. Operate on an
antistatic work surface. For more information on proper handling, see the
Electrostatic Discharge (ESD) application note (SSYA008).
The information in a caution or a warning is provided for your protection. Please read each caution and
warning carefully.
3 FCC Warning
This equipment is intended for use in a laboratory test environment only. It generates, uses, and can
radiate radio frequency energy and has not been tested for compliance with the limits of computing
devices pursuant to subpart J of part 15 of FCC rules, which are designed to provide reasonable
protection against radio frequency communications, in which case the user, at their own expense is
required to take whatever measures necessary to correct this interference.
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www.ti.com Items Required for Operation
4 Items Required for Operation
The following items are required to program a TCA8424:
• TCA8424 EVM with un-programmed TCA8424 in socket
• Single 3.3-V supply
• MSP-EXP430G2 Rev 1.5 Launchpad with MSP430G2553 installed
• USB to mini-USB cable
• PC with Code Composer Studio installed running supplied firmware
• PC with Application GUI installed
The following items are required to evaluate at the system level:
• TCA8424 EVM with programmed TCA8424 in socket
• Breakout wires to connect to keyboard matrix rows and columns
• Keyboard matrix
• Host system with I2C plus INT connected to board
5 Introduction
The benefits of the TCA8424 over other microcontroller-based solutions are lower development costs,
smaller package, and lower power consumption. The lower development costs are seen due to the
TCA8424 requiring programming of only 512 Bytes of OTP versus a full code stack on a microcontroller.
The TCA8424 is fully compliant with HID over I2C based systems with little to no host firmware
development.
The TCA8424 can also be used in a non-Hid over I2C environment by developing host drivers that mimic
the HID over I2C protocol to interpret the input reports. The EVM features a socket to allow easy
programming of multiple units for testing. The code stack supplied with the EVM is designed to interface
with the MSP430G2553 Launchpad to accomplish this. Once programmed, the EVM features breakout
headers for the keyboard and I2C connections to test in customer systems.
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6 TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions
6.1 TCA8424 EVM Schematic
Figure 1 shows the schematic for the EVM. The connections on the EVM are briefly explained in the
subsequent sections.
Figure 1. TCA8424 EVM Schematic
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6.2 Printed-Circuit Board (PCB) Layout
Figure 2 to Figure 5 show the PCB layouts for the TCA8424 EVM.
Figure 2. Layer 1 Top Side: 50-ΩSignal Layer
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Figure 3. Layer 2 (Int1): Ground Plane
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Figure 4. Layer 3 (Int2): 50-ΩSignal with Ground Fill
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Figure 5. Layer 4 Bottom Layer
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www.ti.com TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions
6.3 Bill of Materials
Table 1 is the bill of materials for this EVM.
Table 1. Bill of Materials
ITEM QTY MFG MFG PART# REF DES DESCRIPTION
1 4 PANASONIC LNJ308G8PRA LED1, LED2, LED3, LED4 LED,SMT,0603,PURE GREEN,2.03V
2 1 POMONA ELECTRONICS 2269-0 J1 DUAL INSULATED BANANA JACKS,
BLACK, 0.75LS
3 1 PANASONIC ECJ-1V41E105M C4, C5, C6, C7, C8, C9, C10, C11, CAPACITOR,SMT,0603,CERAMIC,1.0u
F,25V,20%,X5S
4 1 PANASONIC ECJ-1VB0J106M C12 CAPACITOR,SMT,0603,CERAMIC,10u
F,6.3V,20%,X5R
5 1 TAIYO YUDEN TMK107SD472JA C2 CAPACITOR,SMT,0603,CERAMIC,470
0pF,25V,5%,SD
6 1 VISHAY SPRAGUE 594D687X0010R2T C3 CAP,TAN,SMT,10V,20%, 680uF
7 1 PANASONIC EEFUD0K101R C1 CAP,SMT,ELE,100uf,8V,20%
8 1 DIODES INC B230-13-F CR2 DIODE,SCHOTTKY,SMT, DIODES,INC.
9 1 DIODES INC SD103CW-13-F CR1 SCHOTTKEY
DIODE,SMT,20V,400mW,SOD-123
10 1 SAMTEC TSW-104-07-G-D P2 HEADER,THU,8P,2X4,MALE,DUAL
ROW,100LS,100TL
11 1 SAMTEC TSW-108-07-G-D P1 HEADER,THU,16P,2X8,MALE,DUAL
ROW,100LS,100TL
12 2 FCI 66951-010LF P8, P9 HEADER,THU,10P,1X10,FEMALE,SIN
GLE ROW,100LS,200TL
13 6 SAMTEC TSW-101-07-G-S P3, P4, P5, P6, P10, P11 HEADER,THU,1P,MALE,SINGLE
ROW,100TL
14 5 TE Connectivity 9-146281-0-02 P12, P13, P14, P15, P16
15 1 TE Connectivity 9-146281-0-04 P17
16 1 *ENPLAS CORPORATION QFN-40B-0.5-01 DUT3 HTSOCKET,QFN,40P,35x29x16.7mm,
w 2.1hole
17 1 TI TPS77001DBV U2 1.2~5.5V,ULTRA LOW-POWER 50mA
LOW-DROP LINE REGULATOR
18 1 TI TPS27081ADDCR U3 HIGH SIDE LOAD SWITCH WITH LVL
SHFT AND ADJ SLEW RATE
19 1 TI LM2700MTX-ADJ/NOPB U4 LM2700 600KHZ/1.25MHZ,2.5A,
STEPUP PWM DC/DC CONVERTER
20 1 BOURNS SDR0805-100ML L1 INDUCTOR,SMT,2P,POWER,10uH,20
%,RoHS
21 1 VISHAY CRCW060310K0FKEA R21 RESISTOR,SMT,0603,1%,1/10W,10.0K
22 3 VISHAY CRCW0603100KFKEA R10, R11, R12 RESISTOR,SMT,0603,1%,1/10W,100K
23 1 VISHAY CRCW06031K02FKEA R3 RESISTOR,SMT,0603,1%,1/10W,1.02K
24 1 VISHAY CRCW0603150KFKEA R9 RESISTOR,SMT,0603,1%,1/10W,150K
25 1 VISHAY CRCW0603169KFKEA R8 RESISTOR,SMT,0603,1%,1/10W,169K
26 1 VISHAY CRCW060320K0FKEA R15 RESISTOR,SMT,0603,1%,1/10W,20.0K
27 1 VISHAY CRCW06034K64FKEA R2 RESISTOR,SMT,0603,1%,1/10W,4.64K
28 4 PANASONIC ERJ-3GSYJ121 R4, R5, R6, R7 RESISTOR,SMT,0603,5%,1/10W,120
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Table 1. Bill of Materials (continued)
29 5 PANASONIC ERJ-3GSYJ122 R16, R17, R18, R19, R20 RESISTOR,SMT,0603,5%,1/10W,1.2K
30 0 BOURNS 3313J-1-204 R14 PlaceHolder, DO NOT INSTALL
32 0 PANASONIC ECJ-1V41E105M C13 PlaceHolder, DO NOT INSTALL
33 1 Texas Instruments TCA8424RHAR U1 TI device to be used in Socket
34 5 TE Connectivity 382811-8 N/A Jumpers to be installed over P12, P13,
P14, P15, P16
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6.4 VCC and GND Connections
Pin 1 of J1 is a power input to the board and Pin 2 is the GND connection for the board. There are also 4
other GND test points in the corners of the board.
The TCA8424 cannot be powered from the MSP430 Launchpad when programming and needs
an external supply.
Figure 6. VCC and GND Connections
6.5 MSP430 Launchpad Interface
Headers P8 and P9 allow the EVM to interface with the MSP430 Launchpad. If not programming a unit,
jumpers P12, P13, P14, and P16 may be installed, header P15 should be removed. When programming a
unit, an external power supply is needed and all headers except P16 should be installed.
Figure 7. MSP430 Launchpad Interface
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6.6 Breakout Pins
The breakout headers P1 and P2 allow connection of an external keyboard matrix to the EVM. P17 is
connected to the I2C lines of the TCA8424 allowing an external host to communicate to the TCA8424.
Figure 8. Breakout Pins
Table 2. Header Configurations for P1, P2, and P7
P1 P2 P7
Row15 (pin 16) Row14 Col7 Col6 GND (pin 1)
Row13 Row12 Col5 Col4 /INT
Row11 Row10 Col3 Col2 SDA
Row9 Row8 Col1 Col0 (pin 1) SCL
Row7 Row6
Row5 Row4
Row3 Row2
Row1 Row0 (pin 1)
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6.7 LED Outputs
The TCA8424 features LED outputs that are set via the HID SET Report Command in the GUI, discussed
in Section 9, part D.
• Board LED1 = TCA8424 LED0
• Board LED2 = TCA8424 LED1
• Board LED3 = TCA8424 LED2
• Board LED4 = TCA8424 LED3
Figure 9. LED Outputs
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Launchpad Software Setup www.ti.com
7 Launchpad Software Setup
Use the following steps to set up the Launchpad software:
1. Download Code Composer Studio from the Texas Instruments link.
2. With the Launchpad unplugged, configure the headers on the Launchpad to match the yellow box in
the image below:
• The right 3 headers are vertical and the left 2 are horizontal
3. With the Launchpad still unplugged, remove the right-most jumper on the J5 header to match the
yellow box below:
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4. Connect the Launchpad to your computer with a USB to mini cable. A green LED and a red LED
should be on as shown below:
5. Open Code Composer Studio and create a new workspace. Select the “Project” drop down menu and
click on “Import existing CCS/CCE Eclipse Project.” Select Browse on the “Select-search directory”
option and select the location where the source code is stored. Click "Finish" and then select “debug
launch” to load the code to the MSP430G2553 microcontroller. Once completed, disconnect the USB
cable from the LaunchPad.
6. After completing steps 1–5, to load the code at any point for any reason, simply open the workspace
that was created. Ensure that the source code is the active project and the LaunchPad is connected
through USB. Then select “debug launch” to load the code.
If the Launchpad is running and VCC is not connected, the I2C communication will fail. You must
pause the debugger, reset the MSP430 with the "reset CPU" button and then press “play” again.
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GUI Software Setup www.ti.com
8 GUI Software Setup
1. Extract the “TCA8424 GUI.zip” contents to the destination folder of your choice.
2. Double click the setup.exe folder that was extracted in step 1.
3. The following window pops up. Click “Install”.
4. After finishing the installation, the GUI opens and looks like this:
5. To open the GUI in the future, simply double click on the “TCA8424 G.application” file that was
unzipped in step 1.
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9 GUI Walkthrough Guide
A. Connecting the Launchpad to the EVM and PC
1. Install all headers except P16, place an un-programmed TCA8424 in the socket, and power the EVM
board with 3.3 V.
2. Connect the MSP430 Launchpad to the EVM as shown below:
• The connection point is under the board and the USB connector should open towards J1.
3. Connect the Launchpad to your PC.
B. Initiating the connection from the GUI to the Launchpad
1. Open up the device manager on your PC and find which of the COM ports is associated with the
Launchpad.
• COM15 is the COM port associated with Launchpad as shown in the below image (using a local
installation for illustration purposes only):
2. Open the GUI.
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3. Under the "Select Port", there is a drop down menu box which is blank on startup, by default, as
shown below:
4. Click this box, and a list of COM ports will pop up. Select the COM port that is associated with the
Launchpad which was identified in step 1.
• COM 15 from a local installation is shown for illustration purposes:
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5. Now the GUI has opened a connection to the Launchpad and the COM port remains in the drop down
menu box as shown below:
After the connection the Launchpad has been established and the GUI can be fully utilized. The remaining
sections give basic steps on how to use each of the GUI buttons and inputs.
C. Changing the I2C Address
The I2C address in this GUI is referenced with the Read and Write bit included. An address of 0xA8 is
represented in binary as 1010100Xb with the last bit being a 'don’t care'. Address 0xA8 and 0xA9 are both
interpreted as the same address.
The GUI indicates whether an I2C Nack is received by the Launchpad, by presenting a dialog box like
shown below:
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1. Both the Launchpad and GUI default the I2C addresses to 0x76 on startup as shown below:
2. The I2C address must be written into the text box in the default format. Once an address has been
entered, simply click on the “Change I2C address” button to communicate this to the Launchpad.
• If the Launchpad is restarted, the I2C address will default again to 0x76 and must be changed
again if you are working with a different I2C address.
3. Since the default address of the TCA8424 is 0x76 when the OTP is not programmed, leave the default
address in the Launchpad.
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