Texas Instruments TCA8424 User Manual
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Texas Instruments TCA8424 User Manual

Texas Instruments TCA8424 User Manual

Evaluation module
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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 I
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6.3
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TCA8424 EVM Schematic
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VCC and GND Connections
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MSP430 Launchpad Interface
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Breakout Pins
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LED Outputs
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Bill of Materials
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SCDU004 - March 2013
Submit Documentation Feedback
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C™ compliant and is available with a pre-programmed keyboard map.
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Copyright © 2013, Texas Instruments Incorporated
TCA8424 Evaluation Module
Contents
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List of Figures
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List of Tables
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User's Guide
SCDU004 - March 2013
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TCA8424 Evaluation Module
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Summary of Contents for Texas Instruments TCA8424

  • Page 1: Table Of Contents

    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 I C™...

  • Page 2: About This Manual

    About this Manual www.ti.com 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. 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.

  • Page 3: Items Required For Operation

    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 I C based systems with little to no host firmware development.

  • Page 4: Tca8424 Evm Design Circuitry, Bill Of Materials, And Connection Descriptions

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions TCA8424 EVM Schematic Figure 1 shows the schematic for the EVM. The connections on the EVM are briefly explained in the subsequent sections.

  • Page 5: Printed-Circuit Board (Pcb) Layout

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com Printed-Circuit Board (PCB) Layout Figure 2 Figure 5 show the PCB layouts for the TCA8424 EVM. Figure 2. Layer 1 Top Side: 50-Ω Signal Layer SCDU004 – March 2013...

  • Page 6: Layer 2 (Int1): Ground Plane

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com Figure 3. Layer 2 (Int1): Ground Plane TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...

  • Page 7: Layer 3 (Int2): 50-Ω Signal With Ground Fill

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com Figure 4. Layer 3 (Int2): 50-Ω Signal with Ground Fill SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...

  • Page 8: Layer 4 Bottom Layer

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com Figure 5. Layer 4 Bottom Layer TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...

  • Page 9: Bill Of Materials

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com Bill of Materials Table 1 is the bill of materials for this EVM. Table 1. Bill of Materials ITEM MFG PART# REF DES DESCRIPTION PANASONIC LNJ308G8PRA LED1, LED2, LED3, LED4 LED,SMT,0603,PURE GREEN,2.03V...
  • Page 10 TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com Table 1. Bill of Materials (continued) PANASONIC ERJ-3GSYJ122 R16, R17, R18, R19, R20 RESISTOR,SMT,0603,5%,1/10W,1.2K BOURNS 3313J-1-204 PlaceHolder, DO NOT INSTALL PANASONIC ECJ-1V41E105M PlaceHolder, DO NOT INSTALL Texas Instruments TCA8424RHAR...

  • Page 11: 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.

  • Page 12: Breakout Pins

    The breakout headers P1 and P2 allow connection of an external keyboard matrix to the EVM. P17 is connected to the I C lines of the TCA8424 allowing an external host to communicate to the TCA8424. Figure 8. Breakout Pins Table 2.

  • Page 13: Led Outputs

    TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions www.ti.com LED Outputs The TCA8424 features LED outputs that are set via the HID SET Report Command in the GUI, discussed Section 9, part D. • Board LED1 = TCA8424 LED0 •...

  • Page 14: Launchpad Software Setup

    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: •...
  • Page 15 If the Launchpad is running and VCC is not connected, the I C communication will fail. You must pause the debugger, reset the MSP430 with the "reset CPU" button and then press “play” again. SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...

  • Page 16: Gui Software Setup

    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.

  • Page 17: Gui Walkthrough Guide

    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: •...
  • Page 18 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: TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 19 The GUI indicates whether an I C Nack is received by the Launchpad, by presenting a dialog box like shown below: SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 20 C address will default again to 0x76 and must be changed again if you are working with a different I C address. 3. Since the default address of the TCA8424 is 0x76 when the OTP is not programmed, leave the default address in the Launchpad. TCA8424 Evaluation Module SCDU004 –...
  • Page 21 3. After inputting the LED values to be set, click the “SET Report button to set the output report and the LED’s turn on. SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 22 6. The “Reset” button issues the RESET HID Command and the device resets, this clears the output report. If LED’s were on previously, then they will turn off after this command is received. TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 23 “COMMAND and DATA REGISTER” section of the datasheet. 8. The “Read Report” button issues an unaddressed read command to the TCA8424. It populates the same text box as the “Get Report” button does with the contents of the input report, but it will clear an asserted interrupt.
  • Page 24 (c) In the Save as window that pops up, choose the “CSV (Comma delimited) (*csv)” option under the “Save as type” menu (indicated by red box): TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 25 GUI Walkthrough Guide www.ti.com (d) Click “Save” and click "OK" to the message that pops up: (e) Click "Yes" to the next dialog box that opens: SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 26 (f) Exit the .csv file and click "Yes" to the two dialog boxes that show up as shown below: 2. Now that we have a .csv, the OTP contents can be programmed. Click the “Load OTP” button as shown below: TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 27 4. This populates the text box above the “Load OTP” button with the contents of the .csv file. This text box is fully editable, as long as the contents remain in the same format. SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 28 C address must be programmed to a ‘1’ for the OTP contents to be used. If a ‘0’ is programmed at this bit, the OTP will program but the contents will not load into the digital core. TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...
  • Page 29 (a) Click on the “Read OTP” button to read back the OTP contents in the device and populate the textbox above the “Read OTP” button as shown below: SCDU004 – March 2013 TCA8424 Evaluation Module Submit Documentation Feedback Copyright © 2013, Texas Instruments Incorporated...

  • Page 30: Related Documentation

    This causes increased ICC outside of datasheet specifications. Once power cycled, the device ICC returns to normal. Related Documentation TCA8424 Low-Voltage 8x16 Keyboard Scanner with HID over I2C Compliant Interface Datasheet (SCDS341) TCA8424 Evaluation Module SCDU004 – March 2013 Submit Documentation Feedback Copyright ©...
  • Page 31 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue.
  • Page 32 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Texas Instruments TCA8424EVM-038...

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