I DISPLAY I

Ulllted States Patent [19]

Batey, Jr. et al.

US006104512A

[11] Patent Number: 6,104,512

[45] Date of Patent: Aug. 15, 2000

FOREIGN PATENT DOCUMENTS

6369229 3/1988 Japan '

[75] Inventors: Charles E. Batey, Jr.; Carlos M. 5453055 6/1993 Japan '

Rodriguez; John B. Van Zile, all of

Lake Worth, Fla.

OTHER PUBLICATIONS

[73] Assignee: Motorola, Inc., Schaumburg, Ill.

[21] Appl_ No: 09/012,444

_

[22] F1199? Jan- 23, 1998

PageWriterTM 2000 User’s Manual by Motorola, Inc., Docu

Inent N0. 6880496G51—O, 1997.

Williams, Millar, The IrDA Platform, Networks and Com

munications Laboratory, HP Laboratories Bristol,

HPL—95—29, Mar. 1994, HeWlett Packard @ 1995.

Infrared IrDA® Complaint Transceiver, Preliminary Tech

[51] Int C17 H04B 10/00 nical Data pp. 57—62, HSDL—1001, HeWlett Packard.

. . ................................... .............. '

[52] US. Cl. .................. .. 359/152 359/172 340/825.72

IrDA® Dam ' 1_82,

PP PP

’ 455/3’8 3_ 455/522’ HeWlett Packard 1995.

g

. ' ’

[58] Field of Search ................................... .. 359/143, 110,

Motorola MC68328 (DragonBall)TM Integrated Processor

,

359/152_153, 157, 171_172; 455/383, User s Manual, pp. 8—1 thru 8—13, 1995.

69> 522; 340/825~72 Primary Examiner—Kinfe-Michael Negash

[56] References Cited [57] ABSTRACT

U.S. PATENT DOCUMENTS An electronic device (50) includes an infrared transceiver

4 516 221 5/1985 Nakata 364/900 (510) having adjustable infrared signal intensity capability.

4’580’262 4/1986 Naylor """"""""""""""" " 371/5 The electronic device (50) commences to establish commu

476497385 3/1987 Aires et a1. 1.1.......................:::"379/57 nications With a Secondary device (420 and/0r 430) at a ?rst

4:727:600 2/1988 Avakian ................................ .. 455/601

4,777,653 10/1988 Bonnerot er a1 455/69

POWer level, if the Communication hhkis not established, the electronic device (50) increases the IR poWer level and tries

4,804,955 2/1989 YoshiZaWa ...... .. 340/825.44 again to establish communications. In an alternate

4,825,193 4/1989 SiWiak et a1. . 340/311-1

4,825,200 4/1989 Evans et al. ............................ .. 341/23 embodiment, the electronic device (50) includes a poWer level table Which keeps the power level Which has been

4,939,731 7/1990 Reeget a1. .............................. .. 371/532 established for each Secondary device griseglr?oto 175/? using the method described above. The electronic device (50) before

5’075’792 12/1991 Brown egt ' ' ' '

5’O87’982 2/1992 smothers

' ' ' " 359/15'2 communicating With each of the secondary devices deter

359/137 mines the proper poWer level to use depending on the

5j128:942 7/1992 Kojima _ _ _ _ _ _ _ _ _ _

5,128,965 7/1992 Henriksson

5,218,466 6/1993 Brooks .... ..

_ _ _ __ 371/55

____ __ 375/58

359/152 secondary device (420, 430) it Wants to communicate With.

In still a further embodiment, instead of determining the poWer level to use at the start of the communications, an

5,220,678 6/1993 Feei . . . . . . .

572477380 9/ 1993 Lee et a1~

- - - - -- 455/69 ongoing exchange of signal quality information is sent

359/118 betWeen the communicating devices in order to adjust the

2 210151

525461411 8/1996 Leiistch e161: 37/1/55

5,566,022 10/1996 Segev ...... .. 359/172

5,623,355 4/1997 Olsen .................................... .. 359/110

poWer level of the devices during the communication ses

Sion'

30 Claims, 11 Drawing Sheets

52

80

I DISPLAY I

68

82 \

TX/RX

SWITCH

+ 54

r

RECEIVER

+ 70

f

POWER :

SWITCH

[74

REAL T'ME

>

ll

ll

A ll 11 ll 1

CLOCK

1

W84 V K64

INFRARED

TRANSCEIVER

CODE

PLUG g)

DECODER/

f56 f

_ AUDIBLE

CONTROLLER

ALERT

60

f

_ TACTILE

' ALERT

SWITCHES

fee

\

.2

BATTERY

U.S. Patent Aug. 15,2000 Sheet 1 0f 11 6,104,512

52

< >

a2\ ‘

Tx/Rx

SWITCH

K80 r68

TRANSMITTER DISPLAY

+ r54

5_0

56 58

r K

AUDIBLE

RECEIVER —>

+ 70

/

DECODER/

CONTROLLER

POWER <_

SWITCH

r74

REAL T|ME

{

CLOCK

+ 84 f

I

INFRARED CODE

6' 1 TRANSCEIVER PLUG

64 f

I ALERT

60

f

TACTILE

_> ALERT

SWITCHES

86 \62 f

BATTERY

B++

FROM IR 118

EEfVNESFi “’

I

T0 IR

TRANS-4

cEIvER

-/ 110 CENTRAL 114

uART \ > T0

UNIT DRIVER D|SpLAy

112A

\_

FROM

RCvR

102

To 4

POWER

SWITCH

“ma/IE5»

I/O 100

\

OSCILLATOR

FROM

REAL _+

TIME

CLOCK

COUNTER

I l

I

AREIRT

GENERATOR

1128

104

RAM

106

RoM

J TO IR

>

POWER ADJUST

> T0

TRANSMITTER

"0

<—_ FROM CODE

I MEMORY

TO vIBRATOR

> DRIVER

>

TRANSSUCER

DRIVER

CRYSTAL is F G. 2

U.S. Patent Aug. 15,2000

Sheet 2 0f 11 6,104,512

302

WWW

TH

"IIHIIIHII.

U.S. Patent Aug. 15,2000 Sheet 3 0f 11 6,104,512

420

f

PRINTER

SECONDARY

4/

DEVICE #2

FIG. 4

U.S. Patent Aug. 15,2000 Sheet 4 0f 11 6,104,512

>Q0wm 20mm

mom EMJJOEPZOO

Sm

2m

Q |L||||||

Va 8E0 NE J

wmwm 00>

EN m8

U.S. Patent Aug. 15,2000 Sheet 5 0f 11

602

f

D/A

CONVERTER

R

\

604

REG 3v

606

/

TO

LEDA

K606

6,104,512

SET POWER TO

LOWEST LEVEL

+ f

OPEN AN IR

CONNECTION

4

CON-

NECTION

SUCCESFULLY

OPERATED ?

706

YES

7

K08

CONNECTION

ESTABLISHED

|NCREMENT

POWER LEVEL

FIG. 7

POWER

LEVEL 5

MAX ?

712

CONNECTION

FAILED

U.S. Patent Aug. 15,2000

Sheet 6 0f 11

6,104,512

MIN.

I r

4

EXECUTE DISCOVERY

SEQUENCE FOR ALL

SLOTS

4

DID ANY

SECONDARY DEVICES

RESPOND ‘.7

YES

K812

FOR EACH NEW

SECONDARY, IF

THERE IS NO ENTRY

IN TABLE FOR THE

SECONDARY,

RECORD THE POWER

LEVEL IN TABLE

K808

INCREMENT

POWER LEVEL

f816

CONNECTION

NO

FAILED

814

ANY

SECONDARIES

IN TABLE

YES 818

/

CONTINUE WITH

CONNECTION

SEQUENCE

FIG. 8

U.S. Patent Aug. 15,2000 Sheet 7 0f 11 6,104,512

PARAMETER

NEGOTIATION

904

RECEIVE

POWER PACKET

WITHIN

TIMEOUT ?

YES

/- 906

SEND ACK

YES MORE

SECONDARIES

s s r11

6,104,512

PARAMETER

NEGOTIATION

r1002

+ /1004

SET POWER LEVEL

=M|N

+ [1006

4 SEND POWER

PACKET

REAiEILVE

7

YES

f-

111

6

SAVE POWER LEVEL

1010

r

INCREMENT

POWER

LEvEL

1118

POWER

LEVELg

MAX?

1112

1114

FIG. 10

U.S. Patent Aug. 15,2000 Sheet 9 0f 11 6,104,512

PARAMETER

NEGOTIATION

1104

RECEIVE

DISTANCE REQUEST

PACKET WITHIN

TIMEOUT ?

SEND DISTANCE

r1106

PACKET

RECEIVE

POWER

PACKET WITHIN

TIME-OUT

1108

SEND ACK

[-1110

YES

1112

MORE

SECONDARIES

FIG. 11

U.S. Patent Aug. 15,2000 Sheet 10 0f 11

6,104,512

122

f- 0

PARAMETER

NEGOTIATION

+ f

SEND DISTANCE

REQUEST PACKET

(POWER LEVEL : MAX)

1208

RECEIVE

DISTANCE PACKET

WITHIN

TIMEOUT ?

. YES

K1210

TRNSFORM DISTANCE

TO POWER LEVEL P

I K1212

+ [1214

SEND POWER PACKET <

RECEIVE

ACK

?

YES 1222

r

SAVE POWER LEVEL

/.

1218

INCREMENT

POWER

LEVEL

1226

FIG. 12

POWER

LEVEL 5

MAX ?

1220

1224

U.S. Patent Aug. 15,2000 Sheet 11 0f 11 6,104,512

WAITING FOR FRAME

NO

RECEIVE

FRAME WITHIN

TIMEOUT

?

1304

-—>

BER >

THRESHOLD OR

ANY NAK’ d

FRAMES

'?

1306

NO

f- 1308

DEBOUNCE ++

DEBOUNCE >

THRESHOLD

7

YES

{-1312

INCREMENT POWER

LEVEL

f- 1314

DEBOUNCE <

-THRESHOLD

?

1316

1 1

r 3 8

DECREMENT POWER

LEVEL

DEBOUNCE = O

1320

FIG. 13

1

6,104,512

2

BRIEF DESCRIPTION OF THE DRAWINGS

FIELD OF THE INVENTION

FIG. 1 is a block diagram of an electronic device in accordance With the preferred embodiment of the present invention.

This invention relates in general to electronic devices, and more speci?cally to a method for adjusting the poWer level of an infrared signal.

FIG. 2 shoWs a more detailed block diagram of the decoder/controller of FIG. 1 in accordance With the pre ferred embodiment of the invention.

FIG. 3 shoWs an electronic device in accordance With the

BACKGROUND OF THE INVENTION

10 preferred embodiment of the invention.

Some electronic devices use built-in infrared (IR) cir

FIG. 4 shoWs a system in accordance With the invention cuitry in order to alloW them to communicate With other

Which includes an electronic device and other devices Which devices either on a unidirectional or bi-directional basis. For can communicate With each other using IR communications. example, some calculators have built-in infrared circuits

Which alloW them to communicate With printers. While

15 some computer keyboards use built-in infrared links to

FIG. 5 shoWs a schematic of an adjustable IR transceiver circuit in accordance With the invention. communicate With their respective computer system.

FIG. 6 shoWs an alternative adjustable current circuit

Which can be used With the IR transceiver shoWn in FIG. 5.

Infrared links are cost effective solutions and are espe

cially suited for portable electronic devices given that they

FIG. 7 is a ?oWchart highlighting the steps taken to adjust are fairly simply to implement, do not take up much room the IR poWer level in accordance With one embodiment of on the electronic device’s main printed circuit board (PCB) the present invention. and are fairly inexpensive to design-in.

FIG. 8 is a ?oWchart highlighting the steps taken to adjust

Infrared communication links hoWever present several the IR poWer level in accordance With a second embodiment draWbacks over other types of communication links, such as of the present invention.

RS-232 serial links, etc. One draWback to IR communica tions is that if the tWo devices Which are communicating

FIG. 9 is a ?oWchart highlighting the steps taken by a

25 primary device to adjust the IR poWer level in accordance

With each other are placed in very close physical proximity

With a further embodiment of the present invention. to each other, IR distortion due to increased bit error rate may affect the communications if the IR transmitter(s) are operating at high IR poWer (intensity) levels. This problem

FIG. 10 is a ?oWchart highlighting the steps taken by a secondary device to adjust the IR poWer level in accordance

With the embodiment of FIG. 9. typically comes about because the IR transceivers in the

FIG. 11 is a ?oWchart highlighting the steps taken by a electronic devices may be set at a certain poWer level in primary device to adjust the IR poWer level is accordance order to guarantee IR communications at up to a certain

With a further embodiment of the present invention. distance (e.g., one meter) from the other device. In order to meet the distance speci?cation, the IR transceivers are set

35

With IR transmit poWer levels Which Will guarantee com

FIG. 12 is a ?oWchart highlighting the steps taken by a secondary device to adjust the IR poWer level in accordance

With the embodiment of FIG. 11. munications at the given distance (e.g., one meter, etc.),

FIG. 13 is a ?oWchart highlighting the steps taken to

While still providing a high level of noise immunity in a

typical use (e.g., of?ce) environment. One standard setting

adjust the IR poWer level in accordance With a further embodiment of the present invention. body Which sets such speci?cations for the industry is “The

Infrared Data Association” (IrDA), Which has been set up to

DESCRIPTION OF THE PREFERRED establish standards for infrared communications. In order to

EMBODIMENT be compliant With some of the IrDA standard(s), a IR transmitter must typically operate at a high enough poWer cation devices such as tWo-Way pagers, personal digital

assistance (PDAs) having radio communications

Referring noW to the draWings and in particular to FIG. 1, an electrical block diagram of a ?rst electronic device such level to guarantee communications up to a certain distance

45

(e.g., one meter) aWay from another device.

Another problem typically encountered using IR commu as a selective call transceiver (e.g., a tWo-Way pager, etc.) in accordance With the preferred embodiment of the present invention is shoWn. The selective call transceiver nications is found When the IR transmitters (or transceivers) are designed into portable radio frequency (RF) communi

(communication device) 50 comprises an antenna 52 for intercepting transmitted RF signals Which are coupled to the input of a receiver section 54. The RF signals are preferably selective call (paging) message signals Which provide a capabilities, etc. The problem in this environment is that the embedded IR circuitry can sometimes generate noise Which may affect the radio frequency transmissions of the device in question. The noise generation of the IR circuitry is some receiver address and an associated message, such as numeric or alphanumeric message. HoWever, it Will be appreciated

55 that other Well knoWn paging signaling formats, such as tone only signaling or tone and voice signaling, Would be suitable times Worse at higher IR transmissions levels since the for use as Well. The receiver 54 processes the RF signal and electronic device’s poWer supply is more heavily loaded at the higher IR transmit poWer levels.

A ?nal problem typically found With the use of IR circuitry in portable electronic devices is that in situations produces at the output a data stream representative of a demodulated address and message information. The demodulated address and message information are coupled into the input of a decoder/controller 56 Which processes the

Were the IR transmissions are set at high poWer levels, the

IR transceiver operation Will increase the battery charge times for the portable electronic devices When the electronic device is being charged, if IR communications are taking place during the charging of the electronic device. Higher IR

65 levels for portable electronic devices also mean reduced battery life for the portable devices. sWitch 70, coupled to the decoder/controller 56, is used to control the supply of poWer to the receiver 54, thereby providing a battery saving function as is Well knoWn in the art for use With selective call receivers.

For purposes of this illustration, it Will be assumed that the FLEXTM (FLEXTM a trademark of Motorola, Inc.) pro

6,104,512

3

4

tocol for tWo-Way paging Which is Well known in the art is

used, although other signaling formats (e.g., POCSAG, etc.)

could be utiliZed as Well. When the address is received by controller 56, these memory types can also include eXternal memory devices coupled to the controller 56. the decoder/controller 56, the received address information

It Will be appreciated that in many microcomputer

implementations, the programmable-ROM (PROM)

is compared With one or more addresses stored in a code plug (or code memory) 64, and When a match is detected, the message is stored in memory. Optionally, an alert signal is memory area can be provided by, or further include, an

EEPROM (electrically erasable programmable read only

generated to alert a user that a selective call message, or

memory). The oscillator 100, timer/counter 102, RAM 104,

and ROM 106 couple through an address/data/control bus page, has been received. The alert signal is directed to an audible alerting device 58 for generating an audible alert or

10 to a tactile alerting device 60 for generating a silent vibrating alert. SWitches 62 alloW the user of the selective call receiver

108 to a central processing unit (CPU) 110 Which performs the instructions and controls the operations of the micro computer 56. to select betWeen the audible alert 58 and the tactile alert 60

The demodulated data generated by the receiver is coupled into the microcomputer 56 through an input/output in a manner Well knoWn in the art.

The message information Which is subsequently received

15 is stored in memory (not shoWn) and can be accessed by the

(I/O) port 112A. The demodulated data is processed by the

CPU 110, and When the received address information is the same as the code-plug memory Which couples into the user for display using one or more of the sWitches 62 Which microcomputer through an I/O port 112B, the message, if provide such additional functions as reset, read, delete, etc.

Speci?cally, by the use of appropriate functions provided by

any, is received and stored in RAM 104. Recovery of the stored message, and selection of the predetermined destina the sWitches 62, the stored message is recovered from memory and processed by the decoder/controller 56 for tion address, is provided by the sWitches Which are coupled displaying by a display 68 Which enables the user to vieW the to the I/O port 112A.

In one embodiment of the invention, at the time a message is received, an alert signal is generated Which can be routed timing features such as the information required to display time of day information on display 68. Apaging transmitter

80 under the control of controller 56 transmits messages and

25 through the data bus 108 to an alert tone generator 116 that generates the alert signal Which is coupled to the audible alert device 58 that Was described above. Alternatively, couples the transmitter 80 or receiver 54 to antenna 52.

When the vibrator alert is selected as described above, the microcomputer generates an alert enable signal Which is

Preferably, battery 86 is a rechargeable battery variety such

coupled through data bus 108 to the I/O port 112B to enable generation of a vibratory, or silent alert. as those made using nickel-metal hydride cells, etc. Pager 50 also includes an internal infrared transceiver 84 for com

The battery saver operation of pager 50 is controlled by municating With eXternal devices. The internal infrared the CPU 110 With battery saving signals Which are directed transceiver 84 Will be discussed in more detail further beloW.

Although in the preferred embodiment an infrared trans ceiver 84 is used, it can be appreciated that if the pager 50 does not need to have bi-directional communication With the

35 over the data bus 108 to the I/O port 112A Which couples to the poWer sWitch. PoWer is periodically supplied to the receiver to enable decoding of the received selective call receiver address signals and any message information Which is directed to the receiver. Infrared communications to and external devices, an infrared transmitter circuit alone could be utiliZed in order to provide uni-directional IR transmis from the infrared transceiver circuit 84 are coupled to the sions as contemplated by some embodiments of the present invention. controller 56 via universal asynchronous receiver/ transceiver (UART) 118. Information from the real-time

The controller/decoder 56 of FIG. 1 can be constructed clock 74 are also coupled to the controller via I/O port 112A.

Information to be transmitted via RF transmitter 80 are acted utiliZing a microcomputer as shoWn in FIG. 2, although other hardWare arrangements as knoWn in the art can also be upon by the CPU 110 and sent via bus 108 to I/O port 112B. used. FIG. 2 is an electrical block diagram of a microcom

45

In accordance With the present invention CPU 110 provides the needed poWer adjustments signals to infrared transceiver puter based decoder/controller suitable for use in the selec tive call receiver of FIG. 1. As shoWn, the microcomputer 56

84 via I/O 112B as Well be eXplained in more detail further beloW. can preferably comprise a MC68HC05, a MC68HC11, or a

MC68328 processor manufactured by Motorola, Inc., or other similar microcomputers or microprocessors Which

Referring noW to FIG. 3, a top vieW of the tWo Way pager

50 is shoWn. In the preferred embodiment the tWo Way pager preferably include an on-board display driver 114. The

50 comprises an electronic device such as a PAGE microcomputer 56 includes an oscillator 100 Which gener

WRITERTM 2000 tWo-Way pager modi?ed to include the ates the timing signals utiliZed in the operation of the present invention. It is Worth noting that the present inven microcomputer 56. A crystal, or crystal oscillator (not shoWn) is coupled to the inputs of the oscillator 100 to provide a reference signal for establishing the microcom tion can be used With any type of electronic device Which

55 requires, or could use, an IR circuit as Will be explained beloW. Operational control of the device is controlled by a keypad Which includes a plurality of user controls Which

100 and provides programmable timing functions Which are

(random access memory) 104 is utiliZed to store variables derived during processing, as Well as to provide storage of message information Which are received during operation as a selective call receiver as previously discussed. A ROM alloWs a user to move Within different ?elds (user selectable) or button locations Which are displayed on display 68. The general operation (eXcept for the present invention) of a tWo

Way pager 50 is discussed in detail in the PAGEWRITERTM

2000 User’s manual Which is hereby incorporated by refer

(read only memory) 106 stores the subroutines Which con trol the operation of the receiver as Well as the routines

65 required to perform the present invention. Although the

RAM 104 and ROM 106 have been shoWn internal to the ence. An IR port 302 found in the rear of pager 50 provides a port for IR transmissions to be sent and received by pager

50.

In FIG. 4, an IR system is shoWn Which includes pager 50 and a second electronic device such as a printer (also

6,104,512

5 6

referred to as the ?rst secondary device) 420. Communica tions between pager 50 and printer 420 is accomplished via

IR. Printer 420 includes an internal IR transceiver Which level is ?xed. The transmit poWer level for a given session is determined during the discovery phase of the communi cation session. The poWer level is adjusted by controller 56

secondary device 430 (alternate second electronic device)

Which can also communicate With pager 50 is also shoWn in providing the proper signal to the IR poWer adjustment circuit.

FIG. 4. Device 430 also includes a IR transceiver Which alloWs it to have IR communications With pager 50.

2. Packed Based PoWer Management—In this type of poWer management, the IR poWer can vary at any time during a

Referring noW to FIG. 5, a detailed schematic of the IR particular communication session. The transmit poWer for a

given packet of information is determined by signal quality

circuit 84 located Within the pager 50 is shoWn. The IR

10 circuit 84 includes a conventional IR transceiver 510 such as an HSDL1001 IR transceiver manufactured by HeWlett information that is passed along With the packet acknoWl

edgment.

Session Based PoWer Management

Packard, Inc. or other conventional IR transceivers manu factured by other manufacturers. IR transceiver 510 has a built-in IR receiver and transmitter. Data to be transmitted

15 by pager 50 is sent via signal line 508 (labeled IRDA-TXD), the data to be transmitted is processed by controller 56 and sent to the IR transceiver 510 via the transmit signal line

There are several different Ways to implement session based poWer management in accordance With the invention depending on the particular design constraints of the par ticular design at hand. In one application of session based poWer management, the application softWare controls the transmit poWer level of IR transceiver 510, While the con ventional IrDA stack softWare controls the transmit enable to enable the IR transceiver 510. line 512 for the IR transceiver 510. The idea in this appli

IR signals received by the IR transceiver via IR port 302 are decoded by the IR transceiver 510 and sent to controller cation is to attempt a connection (communication link With another device) starting at a minimum poWer level. If the

56 via receive signal line 514 (labeled IRDAiRXD). In connection fails, the IR poWer level is incremented and the accordance With the present invention, the IR poWer level of device retries to set-up a communication link. the IR transmitter found in transceiver 510 is controlled by

25 a control signal sent via line 516 from controller 56. In

This method is highlighted in FIG. 7. In step 702, the IR poWer level is set at a ?rst or loWest poWer level. In step 704, accordance With the preferred embodiment, the control an IR connection betWeen the pager 50 and another device signal adjusts a digital potentiometer 504 Which controls the

(e.g., printer 420) is attempted. If in step 706, the connection

amount of base current in transistor 506. This in effect is successful, in step 708, the communication link is estab controls the amount of current alloWed to How to IR trans lished betWeen the tWo devices at that poWer level. If

ceiver 510, thereby adjusting the poWer level (intensity) of

hoWever in step 706 the connection is not successful, in step the transmitted IR signals. In another embodiment, a ?xed

710 the IR poWer level is incremented to a second poWer resistor could be used in the base of transistor 506 and the level Which is greater than the ?rst poWer level. In step 712, digital potentiometer could be placed betWeen the REG3V it is determined if the current poWer level is set at a level less voltage line 502 and the transistor’s emitter terminal.

35 than or equal to a maximum poWer level Which is predeter

In FIG. 6, an alternate embodiment of the IR poWer adjustment circuit is shoWn, Which can be used With the IR transceiver circuit shoWn in FIG. 5. In this poWer adjustment circuit, a digital to analog converter 602 under the control of controller 56 is used instead of a digital potentiometer. A

?xed resistor 604 is located betWeen the D/A converter 602 mined and stored in the pager 50. If the current poWer level is found to be equal to or less than the maximum poWer level the routine attempts a neW connection in step 704. If in step

712 it is determined that the current poWer level is greater than the maximum alloWable poWer level, the connection is caused to fail in step 714. At Which time an audible or visual and the base terminal of transistor 606. The collector ter indication can be given to the user of pager 50 to let him

510. It should be noted that there are many other circuit designs Which can be implemented by those of ordinary skill in the art Which Would alloW for the adjustment of the transmit IR poWer level of the IR transceiver 510 by controller 56 in order to implement the IR poWer adjustment methods of the present invention discussed beloW. knoW of the connection failure.

The main advantages to this session based application is

45 that it requires no modi?cation to the existing IrDA stack of communication protocols Which may already be residing in the device. This poWer adjustment method lets the electronic device establish an IR link at the loWest required transmit IR poWer level, thereby minimiZing current drain and noise

The IrDA family of protocol speci?cations require that the

generation in device 50. The different poWer levels the pager

IR transceiver support a minimum transmission distance in order to be certi?ed as “IrDA compliant”. For example, to support a minimum transmit distance of 1 meter, the IR transmitter needs to be driven at a very high poWer level

50 can chose from are preferably preprogrammed into the pager 50. The poWer level values adjust the IR poWer adjustment circuit (shoWn in FIGS. 5 and 6) to provide prede?ned IR output transmit intensity levels. These poWer relative to What current pager poWer supplies can typically

55 level values are preferably stored in nonvolatile memory support. In accordance With the present invention, the poWer to the IR transceiver 510 is dynamically adjusted in order to such as EEPROM, etc. These poWer levels values Will cause an adjustment to either digital potentiometer 504 or D/A minimiZe as much as possible the amount of current utiliZed by the electronic device in driving the IR transceiver 510.

The present invention presents several methods of adjusting the poWer level of the IR transceiver 510. The invention encompasses tWo main types of dynamic poWer manage ment for infrared communications betWeen tWo or more electronic devices:

1. Session Based PoWer Management—In this type of poWer

65 management, poWer can vary from communication session to communication session, but for a given session, the power converter 602, Which Will in turn cause a transmit poWer adjustment to occur With IR transceiver 510.

Asecond application of session based poWer management is highlighted in FIG. 8. This method is similar to the method discussed above, hoWever this method is imple mented Within the IrLAP portion of the IrDA stack, Which hides the details of poWer management from the pager’s application programs. For a better detail of IrLAP and other components of the IrDA stack of protocols, one is referred to an article entitled “The IrDA Platform”, by Stuart K.

6,104,512

7 8

Williams and lain Millar, dated Mar. 1994, and Which is

hereby incorporated by reference.

To open a connection, the IrLAP softWare on the primary the maXimum predetermined poWer level threshold has been surpassed as determined in step 810.

Once the discovery phase of the communication link establishment has been completed, pager 50, Will use the

device, pager 50, implements the algorithm described in

FIG. 8. The main idea here is to execute the discovery information in the poWer level table to adjust the IR trans process starting at a minimum transmit poWer level. If no secondary devices respond, the poWer level is incremented ceiver’s poWer level for each of the secondary devices the pager 50 is communicating With in step 818. As such, messages directed individually to each of the secondary and a retry is performed. For each device that does respond, an entry is placed in a table stored in memory that indicates devices Will be transmitted at the loWest poWer level required to achieve communications With that particular the poWer level used for that particular secondary device,

10 secondary device. In the case that pager 50 Wants to broad along With the device’s identi?cation number. This ensures that the minimum poWer level required for each secondary device is used by the primary device. When the primary cast a message to all of the secondary devices at one time, pager 50 Will use the highest poWer level stored in the poWer table for any of the stored secondary devices to guarantee device, in this case pager 50, Wants to communicate With any of the secondary devices Which have responded, it ?rst

15 that all of the secondary devices receive the broadcast message. determines the poWer level to use for that particular sec ondary device by reading the poWer level table stored in

RAM 104 associated With that particular device’s identi? cation number. Thus, When communicating With multiple secondary devices, the transmit poWer level can vary for each one. Pager 50 Will have stored for each of the secondary

Referring noW to FIGS. 9 and 10, a more sophisticated algorithm than that discussed in FIG. 8 is shoWn. This particular method builds on the method discussed With reference to FIG. 8 by adding an additional step Which alloWs the secondary devices 420, 430 to optimiZe their transmit poWer levels as Well. The primary device 50 is able devices an identi?cation number Which corresponds to that particular secondary device and the poWer level value to be used by pager 50 in memory.

In step 802, the poWer level is set to a predetermined

25 to transmit to each secondary device at its optimum poWer level, and each secondary is able to transmit back to the primary at its optimum poWer level. This is done in a fashion that maintains compatibility With secondary devices that are not poWer-enhanced. This method provides a session-based of the communication slots. Each slot in the communication protocol alloWs for communication With a different second poWer management scheme that supports both primary and

secondary devices While maintaining backWard compatibil ity.

ary device, so therefore this application alloWs for the primary device, pager 50, to communicate With multiple

secondary devices (e.g., secondary devices 420 and 430),

To open a connection, the IrLAP softWare on the primary device 50 implements the algorithm described in the How each at its oWn optimum poWer level.

In step 806, the device determines if any of the secondary devices responded to the discovery sequences of step 804. If any of the secondary devices responded, the poWer level used to achieve communications is stored in a poWer level chart in FIG. 8 and as described above. Doing this estab lishes the primary device’s transmit poWer levels for each

35 secondary device it is connected to. The primary device than continues With parameter negotiation in step 902 for the ?rst table stored in the pager’s memory as mentioned above. The the identi?cation number of the particular secondary device secondary device. At the conclusion of parameter negotiation, the secondary device is given the opportunity to perform its poWer management routine as described in the

?oWchart in FIG. 10. The routine for the primary device 50 is shoWn in FIG. 9, While the routine for the secondary

(s) and the poWer level used to achieve the communication link With that device(s).

In step 808, the IR transmit poWer level is incremented if no secondary devices have responded to the communication device(s) is shoWn in FIG. 10.

If a secondary device 420, 430 is not poWer-enhanced, the primary device 50 Will time-out in step 904, and continue message transmitted by pager 50 at the minimum poWer level set in step 802. In step 810 it is determined if the

45

With the neXt secondary device found in the poWer table repeating steps 902—906. If a poWer packet is received from current poWer level is above the preset maXimum poWer the secondary Within the predetermined time-out WindoW, level Which is stored in nonvolatile memory. If the current poWer level has not surpassed the predetermined maXimum the primary sends an acknoWledgment (ACK) message to the secondary device in step 906. The above steps are poWer level Which is stored in pager 50, the process returns to step 804. HoWever, if the poWer level has surpassed the predetermined maXimum poWer level, the routine moves on repeated for each of the secondary units stored in the poWer level table stored in pager 50. Once this is ?nished in step

910, the primary device continues With the communication to step 814.

In step 814, the process determines if there is any infor mation stored for any secondary devices in the poWer level table. If no information is stored for any secondary device in session in step 910.

The secondary device 420 or 430 commences normal parameter negotiations in step 1002. The secondary device

55 sets its transmit poWer level at a predetermined minimum IR the poWer table, the connection process is determined to have failed in step 816. As part of step 816, the pager 50 can transmit poWer level in step 1004. The secondary device than transmits a packet to the primary in step 1006. provide an audio and/or visual alert to the user indicating that a communication link Was not able to be established

With the one or more secondary devices 420 and/or 430.

If in step 806 one or more secondary devices responded to the communication message, the secondary device iden ti?cation number and the poWer level used to achieve communications With the device are recorded and stored in

If an acknoWledgment message is received from the primary device in step 1008, the poWer level used (in this case the minimum poWer level) is stored in a poWer table stored in the secondary device’s memory similar to that described above With reference to FIG. 8 for the primary device in step 1116. Normal communications is then resumed betWeen the primary and secondary devices in step the poWer level table. The routine Will continue to loop through the steps and increment the IR poWer level until all of the secondary devices have established communication or

65

1118.

If no acknoWledgment is received Within a predetermined period of time in step 1008, the secondary device increases

6,104,512

10

its transmit power level in step 1010. It is then determined if the power level is less than or equal to a predetermined maximum level in step 1112. If the maximum poWer level has not been surpassed as determined in step 1112, the routine loops back to step 1006 using the next higher poWer level. If in step 1112 it is determined that the maximum poWer level has been surpassed, the connection fails in step

1114. An alarm can be provided at the secondary device indicating that the connection failed as part of step 1114.

Afurther enhancement to the routines of FIGS. 9 and 10 are shoWn in FIGS. 11 and 12. Assuming that the IR

10 transceiver 84 has fairly consistent transmit and receive characteristics, it is possible to empirically determine the distance betWeen the primary and secondary devices based on the transmit poWer level used to establish the commu

nication link(s). The primary and secondary devices Would

each have a table of average distances indexed by transmit

15

If in step 1216 it is determined that no acknoWledgment has been received Within a certain period of time, the transmit IR poWer level is incremented in step 1218. In step

1220 it is determined if the poWer level is above a certain maximum level. If it is determined that the poWer level is beloW the predetermined maximum level the routine loops back to step 1214. If hoWever, the poWer level is determined to be above the predetermined maximum poWer level, the routine fails in step 1224.

Packet-based PoWer Management

Packet based poWer management is accomplished in accordance With the invention by incorporating poWer related information into the handshake protocol during transmission of data and idle frames betWeen the primary 50 and secondary devices 420, 430. This alloWs the primary and

secondary devices to dynamically adjust poWer throughout

poWer levels. Thus, once the primary device has determined its transmit poWer level using the routines described above, it Would lookup the approximate distance in the table. This a session. This is advantageous When the devices are not stationary for the duration of a session. This routine is an enhancement to the routine discussed With reference to

FIGS. 9 and 10. Those routines are used to establish the distance information Would then be transmitted to the sec ondary device. The secondary device Would use the distance initial poWer levels for all primary and secondary devices.

Then, as each device sends data/idle frames, they Will information to extrapolate a starting transmit poWer level.

This Would help speed up the time it takes the secondary contain additional signal strength information in the form of a bit error rate (BER) measurement or some other Well device to establish the correct poWer level to establish

knoWn measurements (e. g., signal-to-noise ratio, etc.) Which

communications With the primary device. This distance information could also be used by both the primary and

25 provide an indication as to the current conditions of the communication link. For every frame or sequence of frames transmitted by a device, the BER value from the most secondary devices for other purposes (i.e., additional infor mation presented to the user). recently received data is included Within the data area of the

?rst frame or other frame transmitted.

Referring to FIG. 11, the primary device commences parameter negotiations in step 1102. In step 1104 it is

Whenever a primary or secondary device transmits a determined if a distance request packet has been received by frame With the P/F bit set (indicating the last frame in a a particular secondary device Within a time-out WindoW. If sequence “S” has been transmitted and noW is Waiting for a the distance request message has been received in step 1104, response), the next frame received Will contain BER data for the primary device transmits a distance packet Which the frame sequence “S”. Looking at the ?oWchart shoWn in includes the extrapolated distance in step 1106 to the sec

35

FIG., 13, the routine implements a feedback mechanism for poWer adjustments as folloWs: ondary device. In steps 1108—1114, like previously dis cussed With respect to FIG. 9, the primary determines if it has received a poWer packet Within the time-out WindoW in step 1108, it then transmits an acknowledgment signal to the secondary in step 1110 if it received the poWer packet. In

IF ((frame Was NAKed) OR (no ACK/NAK received) OR

(BER>threshold))

THEN increment poWer level step 1112, it is determined if other secondary devices are communicating With the primary, and if so, parameter nego tiations are also commenced for those secondary devices.

The secondary device routine is shoWn in FIG. 12. In step

1202 the secondary device commences parameter negotia

45 tions With the primary device 50. In step 1204, the secondary transmits a distance request packet to the primary device built-in as a further enhancement into this algorithm in order to ?lter out bursty errors and avoid unnecessary poWer adjustments. Idle frames received Will also pref erably contain BER data from the last transmission.

The BER for a particular transmission sequence can be determined using one of a number of Well knoWn BER algorithms knoWn in the art. using the maximum poWer level stored in its memory, in order to have the greatest chance of communicating With the primary device. In decision step 1206, it is determined if the secondary device has received the distance packet from the primary device Within the time-out WindoW. If the distance packet is not received Within the predetermined time-out

WindoW, the communication link fails in step 1208.

Referring to FIG. 13, in step 1302, the device (either a primary or secondary) Waits for an incoming frame. In step

1304 it is determined if the frame has been received Within a predetermined time-out WindoW. If the frame Was received

Within the time-out WindoW, in step 1306 it is determined if level (P) in step 1210. The secondary device in step 1212, sets the poWer level of its IR transceiver to “P” (“P” being the BER is greater than a predetermined BER threshold, or

if any NAK (no acknoWledgment) packets have been

received or no acknoWledgment (ACK) packet have been

If the distance packet is timely received, the secondary

device using its stored distance table information transforms

55 the received distance information into a particular poWer received. If any of these are met, the routine moves on to step 1308. In step 1308, a ?rst debounce counter (labeled as

DEBOUNCE++ in FIG. 13) Which is stored in the device is incremented a predetermined amount. Note that the debounce threshold is different than the BER threshold. one of the available poWer levels) and sends a poWer packet in step 1214 at that poWer level. Like the previously dis cussed algorithms, the secondary device in step 1216, then determines if it has received an acknoWledgment packet from the primary device. If so, the poWer level used is stored in RAM in step 1222 in association With the primary

65 device’s identi?cation information, and the devices continue

With normal communications in step 1226.

In step 1310, it is determined if the debounce value is greater than a ?rst prede?ned debounce threshold level stored in the device. If it is, then in step 1312 the poWer level is incremented and the debounce value is set at Zero (reset).

In step 1320, the communication betWeen the tWo devices continues With the device again Waiting for a frame to receive or a frame to transmit.

6,104,512

11 12

If in step 1306 it is determined that the BER is less than

the prede?ned threshold, a negative acknowledgment

(NAK) has been received or no acknowledgment (ACK) has been received , in step 1314, a negative debounce counter

(labeled DEBOUNCE—in FIG. 13) is decreased. In step

1316, it is then determined if the debounce value is less than a negative or second threshold level (labeled as tronic device to establish the IR communication link

With the second electronic device.

6. A method as de?ned in claim 5, Wherein the ?rst electronic device uses the poWer level it stored to commu nicate With the second electronic device after the IR com municate link has been established betWeen the ?rst and second electronic devices.

“—THRESHOLD” in FIG. 13) also stored in the device. If electronic device after the ?rst electronic device has estab the debounce value is loWer than the threshold, in step 1318, the IR transmit poWer level is decremented and the lished a communication link With the second electronic device performs the folloWing steps in order to determine debounce value is set reset. The routine then moves on to step 1320. the proper transmit poWer level for it to use When commu nicating With the ?rst electronic device:

With the present invention one or more devices Which are communicating With each other can optimiZe there IR trans

(e) attempting to establish an IR communication link With the ?rst electronic device at a ?rst poWer level; mission poWer levels in order to conserve poWer. The

15 methods presented above are extremely bene?cial especially

(f) determining if the IR communication link betWeen the

for portable electronic devices Which operate using batteries,

since the IR transmit poWer levels are adjusted for the

?rst electronic device and the second electronic device

Was established; and

(g) attempting to establish the IR communication link operating conditions at hand. The several embodiments discussed above provide different levels of sophistication

With the ?rst electronic device at a second poWer level

Which is greater than the ?rst poWer level if the

depending upon the particular system requirements.

communication link in step Was not established.

While the preferred embodiments of the invention have

8. A method as de?ned in claim 7, Wherein the ?rst been illustrated and described, it Will be clear that changes, of the present invention as de?ned by the appended claims.

What is claimed is: electronic device transmits a signal back to the second variations, substitutions and equivalents Will occur to those skilled in the art Without departing from the spirit and scope

25 electronic device if it receives a message from the second electronic device and the second electronic device upon receiving the signal from the ?rst electronic device deter mines that the IR communication link betWeen the ?rst and poWer level of a ?rst electronic device’s infrared transmitter

Which is attempting to establish a communication link With a second electronic device, the ?rst electronic device having a memory, comprising:

(a) storing in the memory a time-out period;

(b) attempting to establish the IR communication link

With the second electronic device at a ?rst poWer level;

35

(c) Waiting for the time-out period to elapse; and

second electronic devices has been established. electronic device upon receiving the signal from the ?rst electronic device performs the folloWing further step:

(h) storing at the second electronic device an identi?ca tion number for the ?rst electronic device along With information on the poWer level used by the second electronic device to establish the IR communication link With the ?rst electronic device.

(d) attempting to establish the IR communication link

With the second electronic device at a second poWer level Which is greater than the ?rst poWer level if the communication link Was not established.

2. A method as de?ned in claim 1, Wherein step (d)

comprises the sub-steps of:

electronic device after a communication link has been established With the ?rst electronic device transmits a mes sage to the ?rst electronic device having a bit error rate

(BER) information.

(d1) sending a control signal to the infrared transmitter; and

(d2) increasing the amount of current supplied to the infrared transmitter in response to the control signal in order to place the IR transmitter at the second poWer level.

45 electronic device increases the poWer level Which it uses to communicate With the second electronic device if the BER information received from the second electronic device indicates that the BER is above a predetermined threshold level.

12. A method as de?ned in claim 10, Wherein the ?rst electronic device decreases the poWer level Which it uses to communicate With the second electronic device if the BER

(e) providing an indication at the ?rst electronic device that the communication link Was not established if step information received from the second electronic device indicates that the BER is beloW a predetermined threshold

(d) fails to establish the IR communication link With the second electronic device. electronic device transmits a signal back to the ?rst elec

55 level.

13. Amethod as de?ned in claim 1, comprising the further steps of: tronic device if it receives a message from the ?rst electronic device and the ?rst electronic device upon receiving the signal from the second electronic device determines that the

IR communication link betWeen the ?rst and second elec tronic devices has been established.

(e) determining a distance value stored in the ?rst elec tronic device corresponding to the poWer level used to establish the communication link With the second elec tronic device; and

(f) transmitting the distance value to the second electronic

5. A method as de?ned in claim 4, Wherein the ?rst electronic device upon receiving the signal from the second electronic device performs the folloWing further step: device.

14. A method as de?ned in claim 13, comprising the further steps of:

(e) storing at the ?rst electronic device an identi?cation number for the second electronic device along With information on the poWer level used by the ?rst elec at the second electronic device:

(g) receiving the distance value transmitted by the ?rst electronic device;

6,104,512

13

14

(h) determining a power level stored in the second electronic device associated With the received dis tance value; and

(i) using the poWer level determined in step (h) to communicate With the ?rst electronic device.

15. Amethod for automatically adjusting the infrared (IR)

poWer level of an electronic device’s infrared transmitter for

(d) increasing the IR poWer level to a second IR poWer level Which is greater than the ?rst IR poWer level if in

25 step (b) it is determined that not all of the plurality of secondary devices Were able to establish an IR com munication link With the electronic device at the ?rst poWer level.

(d) determining a distance value stored in the ?rst elec tronic device corresponding to the poWer level used to establish the communication link With the second elec tronic device; and

5 (e) transmitting the distance value to the second electronic device.

19. A method as de?ned in claim 18, comprising the further steps of: an electronic device Which is attempting to establish a communication link With a plurality of secondary devices,

comprising:

(a) attempting to establish IR communication links With the plurality of secondary devices at a ?rst IR poWer

level;

(b) determining if the IR communication link betWeen the electronic device and the plurality of secondary devices

15

Was established;

(c) storing for each amongst the plurality of secondary

at the second electronic device:

(f) receiving the distance value transmitted by the ?rst electronic device;

(g) determining a poWer level stored in the second electronic device associated With the received dis tance value; and

(h) using the poWer level determined in step (g) to communicate With the ?rst electronic device.

20. A method as de?ned in claim 18, Wherein step (d)

comprises the sub-steps of:

devices Which Was able to establish a communication link With the electronic device, device identi?cation information and the ?rst poWer level information at the electronic device; and

(d1) sending a control signal to the infrared transmitter; and

(d2) increasing the amount of current supplied to the infrared transmitter in response to the control signal in order to place the IR transmitter at the second poWer level.

(f) providing an indication at the ?rst electronic device that the communication link Was not established if step

(d) fails to establish the IR communication link With the second electronic device.

(e) attempting to establish a communication link using the second IR poWer level With those amongst the plurality of secondary devices Which did not establish a com poWer level; electronic device transmits a signal back to the ?rst elec tronic device if it receives a message from the ?rst electronic munication link With the electronic device at the ?rst IR device and the ?rst electronic device upon receiving the signal from the second electronic device determines that the

35

IR communication link betWeen the ?rst and second elec

(f) determining if IR communication links betWeen the electronic device and With those amongst the plurality tronic devices has been established.

23. A method as de?ned in claim 22, Wherein the ?rst of secondary devices Which did not establish an IR electronic device upon receiving the signal from the second communication link With the electronic device at the electronic device performs the folloWing further step:

?rst IR poWer level Were established; and

(g) storing for each amongst the plurality of secondary

devices Which Was able to establish an IR communi

(f) storing at the ?rst electronic device an identi?cation number for the second electronic device along With information on the poWer level used by the ?rst elec cation link With the electronic device in step (f), device tronic device to establish the IR communication link identi?cation information and the second poWer level information at the electronic device.

45

With the second electronic device.

24. A method as de?ned in claim 23, Wherein the ?rst tronic device before attempting to communicate With any of the plurality of secondary devices determines the particular identi?cation number for the secondary device from amongst the plurality of secondary device Which it Wants to communicate With and determines if it has stored in a poWer

established;

electronic device uses the poWer level it stored to commu nicate With the second electronic device after the IR com municate link has been established betWeen the ?rst and second electronic devices. level table a poWer level Which is associated With that particular identi?cation number.

18. Amethod for automatically adjusting the infrared (IR)

poWer level of a ?rst electronic device’s infrared transmitter

(a) attempting to establish the IR communication link

With the second electronic device at a ?rst poWer level; electronic device after the ?rst electronic device has estab lished a communication link With the second electronic device performs the folloWing steps in order to determine the proper transmit poWer level for it to use When commu nicating With the ?rst electronic device:

Which is attempting to establish a communication link With a second electronic device, comprising:

(b) determining if the IR communication link betWeen the

?rst electronic device and second electronic device Was

(f) attempting to establish an IR communication link With the ?rst electronic device at a ?rst poWer level;

(g) determining if the IR communication link betWeen the

?rst electronic device and the second electronic device

Was established; and

(h) attempting to establish the IR communication link

With the ?rst electronic device at a second poWer level

(c) attempting to establish the IR communication link

With the second electronic device at a second poWer

65 level Which is greater than the ?rst poWer level if the communication link in step (b) Was not established;

Which is greater than the ?rst poWer level if the communication link in step (e) Was not established.

26. A method as de?ned in claim 25, Wherein the ?rst electronic device transmits a signal back to the second

6,104,512

15

electronic device if it receives a message from the second electronic device and the second electronic device upon receiving the signal from the ?rst electronic device deter mines that the IR communication link betWeen the ?rst and second electronic devices has been established. electronic device upon receiving the signal from the ?rst electronic device performs the folloWing further step:

(i) storing at the second electronic device an identi?cation number for the ?rst electronic device along With infor mation on the poWer level used by the second elec tronic device to establish the IR communication link

With the ?rst electronic device.

16

sage to the ?rst electronic device having a bit error rate

(BER) information.

29. A method as de?ned in claim 28, Wherein the ?rst electronic device increases the poWer level Which it uses to communicate With the second electronic device if the BER information received from the second electronic device indicates that the BER is above a predetermined threshold level.

30. A method as de?ned in claim 28, Wherein the ?rst electronic device decreases the poWer level Which it uses to communicate With the second electronic device if the BER information received from the second electronic device indicates that the BER is beloW a predetermined threshold level. electronic device after a communication link has been

15 established With the ?rst electronic device transmits a mes

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