battery-less near field communication (nfc) keyboard

User's GuideTIDU398–July 2014

Battery-Less Near Field Communication (NFC) Keyboard

Abstract: To be provided.

Contents1 Hardware Block Diagram ................................................................................................... 22 How to Mount the PCBA in the Keyboard ................................................................................ 23 How to Program the New NFC Keyboard PCBA ........................................................................ 94 Schematic ................................................................................................................... 105 Power Consumption Test ................................................................................................. 106 Android Applications ....................................................................................................... 12

List of Figures

1 Hardware Block Diagram ................................................................................................... 22 New Keyboard—Open Box................................................................................................. 23 Turn Over Keyboard......................................................................................................... 34 Remove Screws.............................................................................................................. 45 Turn Keyboard Face Up .................................................................................................... 46 Release the Hidden Lock ................................................................................................... 57 Open the Cover .............................................................................................................. 58 Remove Battery From the Keyboard ...................................................................................... 69 Detach the 26-Pin FPC ..................................................................................................... 710 Attach New NFC Keyboard PCBA......................................................................................... 811 Re-Mount Screws............................................................................................................ 812 NFC Keyboard PCBA ....................................................................................................... 913 MSP430 USB-FET JTAG Interface........................................................................................ 914 Schematic ................................................................................................................... 1015 Power Received from NFC Antenna..................................................................................... 1116 Power Consumed by MCU+CL330 and CL330 Itself.................................................................. 1117 System Block Diagram .................................................................................................... 1218 NfcServer.................................................................................................................... 1219 NfcKeyboard ............................................................................................................... 13

1TIDU398–July 2014 Battery-Less Near Field Communication (NFC) KeyboardSubmit Documentation Feedback

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keypad matrix

NFCtype 4

Keyboardscan

MSP430FR5739RF430CL330

I2 C

3.3 V

GPIO

Antenna

Power drain& Rectifier

TPS70933

Hardware Block Diagram www.ti.com

1 Hardware Block Diagram

Figure 1. Hardware Block Diagram

2 How to Mount the PCBA in the Keyboard1. Open the box.

Figure 2. New Keyboard—Open Box

2 Battery-Less Near Field Communication (NFC) Keyboard TIDU398–July 2014Submit Documentation Feedback


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www.ti.com How to Mount the PCBA in the Keyboard

2. Turn the keyboard face down (see Figure 3).

Figure 3. Turn Over Keyboard



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How to Mount the PCBA in the Keyboard www.ti.com

3. Remove all of the screws (see Figure 4).

Figure 4. Remove Screws

4. Turn the keyboard face up (see Figure 5).

Figure 5. Turn Keyboard Face Up



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5. Release the hidden lock in both sides by using a thin object (see Figure 6).

Figure 6. Release the Hidden Lock

6. Open the cover to see the PCBA with battery (see Figure 7)

Figure 7. Open the Cover



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7. Remove all of the screws and remove the battery from the keyboard (see Figure 8).

Figure 8. Remove Battery From the Keyboard



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8. Detach the 26-pin FPC from the PCBA (see Figure 9).

Figure 9. Detach the 26-Pin FPC



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9. Attach the new NFC keyboard PCBA without the battery (see Figure 10).

Figure 10. Attach New NFC Keyboard PCBA

10. Re-mount all of the screws (see Figure 11).

Figure 11. Re-Mount Screws



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1

2

TPS70933 RF430CL330H MSP430FR5739

1. ANT1 +2. ANT0 +3. ANT0 ±4. NC 5. ANT1 ±

5. FET-TDO4. FET-VCC3. FET-GND2. FET-TEST1. FET-TCK

FPC-26

www.ti.com How to Program the New NFC Keyboard PCBA

3 How to Program the New NFC Keyboard PCBA

Figure 12. NFC Keyboard PCBA

3.1 Spy-Bi-Wire Programming InterfaceAs illustrated in Figure 12, P3 in the PCBA is the 2-wire JTAG communication interface. To debug orprogram the onboard MSP430RF5739, you need connect all the signals on P3 to a MSP430 USB-FET. A330-Ω resister is mounted on the PCB between the TCK and TEST pin. Note that FET will power thePCBA during the programming progress.

3.2 MSP430 USB-FET JTAG interface

Figure 13. MSP430 USB-FET JTAG Interface



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VCC1

ANT12

ANT23

RST4

E05

E16

E27

INTO8

CS9

SCK10

SCL11

SDA12

VCORE13

GND14

U2

RF430CL330H

C11uF

C3

0.1uF

C20.47uF

INTO

R347kR2

47k

GND

C4TBD

C5TBD

R4

0

R1

0

R50

R60

R70

GND

VCC_CL330

VCC_CL330

C6

0.47uF

RST_330

GND

SDASCL

SDASCL

GND

1 23 45 67 89 1011 1213 1415 1617 1819 2021 2223 2425 26

P2

KB

K_X0 K_X1K_X2 K_X3K_X4 K_X5K_X6 K_X7K_X8 K_X9K_X10 K_X11K_X12 K_X13K_X14 K_X15K_X16 K_X17K_Y0 K_Y1K_Y2 K_Y3K_Y4 K_Y5K_Y6 K_Y7

K_Y0K_Y1K_Y2K_Y3K_Y4K_Y5K_Y6K_Y7

K_X0K_X1K_X2K_X3K_X4K_X5

K_X6K_X7K_X8K_X9K_X10K_X11K_X12K_X13

P1.0P1.1P1.2

P3.0P3.1P3.2P3.3

P1.3P1.4P1.5

PJ.0PJ.1PJ.2PJ.3

P4.0P4.1

P2.5P2.6

TEST

/RST

P2.0P2.1P2.2

P3.4P3.5P3.6P3.7

P1.6P1.7

VCORE

DVSSDVCC

P2.7

P2.3P2.4

AVSS

PJ.4PJ.5

AVSSAVCC

U3

MSP430FR5739IRHA

K_X14K_X15

K_X16K_X17

VCC_CL330

RST

TEST

GNDGND

GND

VCC_MCU

VCC_MCU0.1uF

C7

0.1uF

C10

2.2nF

C11

GND

47kR21

VCC_MCU

GND

RST_330

12345

P1

Antenna

ANT1_PANT1_N

ANT2_N

ANT2_P

ANT2_PANT2_N

R13

N/A

R17

N/A

ANT1_P

ANT1_N 22uF

C9

IN1

2

EN3

OUT5

GND

U1 TPS70933DBV

10uF

C8

GND

GND

VCC

0R20

12

3

D1

BAS40-04LT1G

12

3

D2BAS40-04LT1G

GND

RST

TEST

0R18

VCC

22uFC13

Do not mount R13, R17

22uFC14

22uFC15

22uFC16

0.1uFC12

330R10

R8 0

12345

P3

FET-TCKFET-TEST

FET-VCCFET-TDO

FET-GND

R9 0

VCC_MCU

R120

R11

Schematic www.ti.com

4 Schematic

Figure 14. Schematic

5 Power Consumption Test• Test based on Schematic 2.0 / PCB Rev B.• Different mobile placement resulted different I_REGOUT but the same V_REGOUT, which may be

clamped by the LDO input circuit.



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I_MCU / V_MCU I_CL330

I_MCU (mA) V_MCU (v) I_CL330 (uA)

no operation 0.85

3.3

66~70single key stroke 0.9

multiple keys stroke(2 ~ 5 keys) 1.0~1.4

I_REGOUT / V_REGOUT

Mobile I_REGOUT (mA) V_REGOUT (v)

Samsung Note2

1.42 11.431.58 11.522.11 11.68

2.8 11.76

Nexus S

1.75 11.592.4 11.72

2.92 11.76

3.32 11.78

www.ti.com Power Consumption Test

5.1 Current Measured on LDO Input

Figure 15. Power Received from NFC Antenna

5.2 Current Measured on MSP430 and CL330

Figure 16. Power Consumed by MCU+CL330 and CL330 Itself

Note that MSP430RF5739 powers RF430CL330, so the current I_MCU is included in the power thatCL330 consumes.



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Characters received

Raw data received

History information

NfcServer

NfcKeyboard Hello world!Text

Key stroke

Helper application

Input method service other application / controls

NDEF message

NFCNDEF

tranceiver

ring buffer

scan code

125ms interval

Android Applications www.ti.com

6 Android ApplicationsFigure 17 illustrates the system block diagram. This system has mobile phone and keyboard components.To operate the NFC keyboard, you need an NFC-enabled mobile phone running on Android 2.3 or laterversion and also the NFC batteryless keyboard. On the mobile phone, two (Android) applications need tobe installed. One is NfcServer (an application that collects the key strokes via NFC communication), whichis the Android side and defined as an NDEF message. After NfcServer gets the NDEF message, it willparse what is in the message (the message contains the original scan code of the key activity). Then, thescan code is handled and explained, and the character is sent to the other application, NfcKeyboard,which is an input method service in the Android system. NfcKeyboard is a simple service; the program justsends the characters and text or any control information to the other application if it uses the system editcontrols.

Figure 17. System Block Diagram

6.1 NfcServer Application

Figure 18. NfcServer

This application is designed to be a helper application and can run in the background; you can hide thisapplication by pressing the Home/Back button on the mobile phone or the Hide button in the graphicaluser interface (GUI). Even when the program is hidden, it still communicates with the keyboard via theNFC connection.



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www.ti.com Android Applications

Limited by the Android NFC mechanism, this application may have to be called each time the NFC reader(mobile phone) and NFC device (keyboard) approaching.

In this GUI, you can see the NDEF message sent by the keyboard. The upper side of the GUI containsthe characters decoded by the application, and in the lower side of the GUI, you can see the raw datacontained in the NDEF message. It also maintains history information that indicates the communicationerrors. This function is designed for debug usage and should be eliminate in a real application.

6.2 NfcKeyboard ApplicationThe NfcKeyboard application is an input method service application that the Android system uses for userinput. You can see many of such applications implementing different language input.

You can only input Latin characters and symbols in this simple application by default. Efforts must betaken for support with other language input.

NfcKeyborad implements an input method named “NFC Keyboard” that you can find on Language & Inputonce you installed the application. In the Language & Input menu option, check the NFC Keyboard andalso make it the default input method to enable the NfcKeyboard access. Note that when you test thekeyboard with the NfcServer application, you do not need to install or change the input method as theNfcServer application handles the message by itself.

Figure 19. NfcKeyboard



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battery-less near field communication (nfc) keyboard

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