(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2005/0268000 A1
`Carlson
`(43) Pub. Date:
`Dec. 1, 2005
`
`US 2005O268000A1
`
`(54) ACCESSORY IDENTIFIER IN AN
`ELECTRONIC DEVICE
`(76) Inventor: Mark J. Carlson, Round Lake, IL (US)
`Correspondence Address:
`MOTOROLAINC
`600 NORTH US HIGHWAY 45
`ROOM AS437
`LIBERTYVILLE, IL 60048-5343 (US)
`9
`10/857,123
`May 28, 2004
`Publication Classification
`
`(21) Appl. No.:
`(22) Filed:
`
`(51) Int. Cl." ..................................................... G06F 13/00
`
`(52) U.S. Cl. ................................................................ 710/15
`(57)
`ABSTRACT
`An apparatus (100) and a method (200) for an accessory
`identifier for identifying a connected accessory type from
`three or more accessory types (102, 104,106) are provided.
`Each of the three or more accessory types (102, 104,106)
`h
`identifi
`istor (108. 110, 112), which i
`as a unique identifier resistor (108,
`9
`), which is
`accessible through an identification pin (114, 116, 118) and
`is linearly related to each other in resistance value. Using a
`voltage Source (120), presence of the connected accessory
`(102) is detected (204) by monitoring a voltage change at the
`Source pin (126). Once the presence is detected, a predeter
`mined current is sent through the Source pin (126) and the
`resulting voltage at the Source pin (126) is measured (208),
`and based upon the measured Voltage, the connected acces
`sory type (102) is identified (210).
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`2O2
`
`DETECT PRESENCE OF
`CONNECTED ACCESSORY
`
`PROVIDE PREDETERMINED CURRENT
`THROUGH IDENTIFICATION PIN
`
`MEASURE VOLTAGE AT
`IDENTIFICATION PIN
`
`2O4
`
`
`
`
`
`
`
`IDENTIFY CONNECTED ACCESSORY
`TYPE BASED UPON MEAUSRED WOLTAGE
`
`210
`
`DISCONTINUE
`PREDETERMINED CURRENT
`
`MONITOR CHANGE IN WOLTAGE
`A IDENTIFICATION PIN
`
`212
`
`214
`
`
`
`REMOVAL
`DETECTED?
`
`200
`
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`

`Patent Application Publication Dec. 1, 2005 Sheet 1 of 2
`
`US 2005/0268000 A1
`
`a
`
`EY to r
`
`- -
`
`132
`
`114
`co-e
`
`126
`
`102
`
`- - - - -
`
`3-108
`
`PRESENCE
`130 DETECTOR
`
`|
`
`
`
`136
`
`CURRENT
`SOURCE
`
`- - - - -
`
`104
`r - - - -
`
`S-11O
`
`F
`- - - - -
`
`106
`- - - -
`
`-N112
`
`116
`
`118
`
`1OO
`
`Af7G 7
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`

`Patent Application Publication Dec. 1, 2005 Sheet 2 of 2
`
`US 2005/0268000 A1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`2O2
`
`DETECT PRESENCE OF
`CONNECTED ACCESSORY
`
`PROVIDE PREDETERMINED CURRENT
`THROUGH IDENTIFICATION PIN
`
`MEASURE VOLTAGE AT
`IDENTIFICATION PIN
`
`2O4
`
`2O6
`
`
`
`
`
`
`
`O
`
`IDENTIFY CONNECTED ACCESSORY
`TYPE BASED UPON MEAUSRED WOLTAGE
`
`21O
`
`DISCONTINUE
`PREDETERMINED CURRENT
`
`MONITOR CHANGE IN VOLTAGE
`AT IDENTIFICATION PIN
`
`212
`
`214
`
`
`
`REMOVAL
`DETECTED?
`
`2OO
`
`Af7G 2
`
`FISI Ex 2007-p 3
`Huawei v FISI
`IPR2018-00465
`
`

`

`US 2005/0268000 A1
`
`Dec. 1, 2005
`
`ACCESSORY IDENTIFIER IN AN ELECTRONIC
`DEVICE
`
`FIELD OF THE INVENTION
`0001. The present invention generally relates to a data
`bus connection, and more specifically to detection and
`identification of an accessory attachment through the data
`bus connection.
`
`BACKGROUND OF THE INVENTION
`0002 Portable electronic devices, such as personal digital
`assistants (“PDAs”), personal computers (“PCs”) and cel
`lular telephones, are generally capable of accepting external
`accessories Such as, but not limited to, a camera, a speaker
`phone, and a battery charger. An electronic device, which
`supports the “MiniUSB Analog Carkit Interface Specifica
`tion” (“CEA-936”) published by Consumer Electronics
`ASSociation, Dec. 1, 2002, is required to detect presence of
`an accessory at all times through an identification ("ID") pin
`of a connector that accepts the accessory. In addition, the ID
`pin is also used to identify the type of the accessory attached
`to the electronic device. Presently, the identification of
`accessory types is implemented by using a regulated Voltage
`and precision resistors to make a precise measurement of the
`ID pin Voltage. The measured ID pin voltage is then used to
`determine what accessory is currently attached to the elec
`tronic device. However, the use of a regulated Voltage and
`precision resistors adds overall cost to the electronic device
`in terms of number of parts required for the implementation
`or as an integration cost for the required parts.
`0.003
`Presently, different resistance values to ground are
`commonly used in external bus designs for detection and
`identification of accessories. However, because the CEA
`936 interface is designed to be compatible with the existing
`Universal Serial Bus (“USB”) interface, the range of iden
`tification resistors becomes very limited, typically in exceSS
`of 100 kS2, which necessitates tighter tolerance and higher
`precision methods for detecting and identifying accessories.
`Further, because the electronic device is required to detect
`presence of an accessory at all times through the ID pin, the
`design using different resistance values to ground for detec
`tion and identification of accessories carries the burden of
`higher current drain due to the fact that the regulated Supply
`must be on at all times.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0004 FIG. 1 is a block diagram of an accessory identifier
`in accordance with the preferred embodiment; and
`0005 FIG. 2 is a flowchart for an accessory identifier in
`accordance with the preferred embodiment.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`0006 The accessory identifier provides an apparatus and
`a method in an electronic device for detecting and identi
`fying an attached accessory from various attachable acces
`Sories. Each of the attachable accessories has a unique
`resister, or an identification resister, connected between an
`identification pin of the attachable accessory and ground. In
`a detection mode, the electronic device applies a predeter
`mined Voltage provided by a Voltage Source at a Source end
`of a pullup resister, which is designed to connect to the
`
`identification pin of an attachable accessory at a receiving
`end upon attachment. A change in Voltage at the receiving
`end is monitored to detect presence of the attachable acces
`Sory. If there was no attachment, the Voltage at the receiving
`end would be the full predetermined voltage of the voltage
`Source because it is an open circuit. However, if there was
`an accessory attached, then the pullup resister and the
`identification resister of the attached accessory would form
`a Voltage divider, and the Voltage at the receiving end would
`be proportionate to a resistance ratio of the pullup resister
`and the identification resister. In the detection mode, it
`Suffices to notice a change in Voltage from the predetermined
`Voltage at the receiving end of the pullup resister to deter
`mine the attachment or removal of an accessory. Once the
`presence is detected, the electronic device then identifies the
`attached accessory based upon the identification resistor.
`Instead of continuing to use the Voltage divider, which
`would require a regulated Voltage Source and exponentially
`increasing identification resistor values to differentiate types
`of accessories, an identification mode based upon a current
`Source is used. By providing a predetermined current to the
`identification resistor, resistance values used to differentiate
`accessories can be linearly Spaced instead of exponentially
`Spaced as in the Voltage divider method, and the regulated
`Voltage Source is no longer required.
`0007 FIG. 1 is a block diagram of an accessory identifier
`100 in accordance with the preferred embodiment. The
`accessory identifier 100 is configured to identify a connected
`accessory type 102 from three or more accessory types (only
`three accessory types 102,104, and 106 are shown). Each
`accessory type 102,104, and 106 has a unique identification
`resister 108, 110, and 112 accessible through an identifica
`tion pin 114, 116, and 118. The accessory identifier 100 has
`a Voltage Source 120, which is connected to a Source resister
`122 at its Source end 124, and is configured to apply a
`predetermined Voltage at the Source end 124. The Source
`resister 122 is also coupled to a Source pin 126, which is
`designed to connect to the identification pin 114, 116, or 118
`when an accessory is attached. A voltage detector 128 is
`coupled to the Source pin 126, and is configured to monitor
`the voltage at the source pin 126. A presence detector 130 is
`coupled to the Voltage detector 128 to detect presence of the
`connected accessory 102 based upon a change in the mea
`sured voltage at the source pin 126. When there is no
`accessory connected, the Source resister 122 is an open
`circuit and the Voltage at the Source pin 126 is the prede
`termined voltage supplied by the voltage source 120. How
`ever, when there is an accessory attached, Such as the
`connected accessory 102, the Source resister 122 and the
`identification resister 108 function as a voltage divider, and
`the Voltage at the Source pin 126 is less than the predeter
`mined voltage of the voltage source 120. The voltage
`detected at the Source pin 126 may be Stored in a memory
`132, which is coupled to the voltage detector 128. The
`presence detector 130 may compare the Stored Voltage
`against the measured Voltage at the Source pin 126 to detect
`a change in Voltage and to determine when the connected
`accessory 102 has been removed.
`0008. Once the presence of a connected accessory 102 is
`detected, a mode Switch 134, which is coupled to the
`presence detector 130, disconnects the Source resister 122
`from the Source pin 126, and connects a current Source 136
`to the Source pin 126, enabling a predetermined current from
`the current source 136 to flow through the identification
`
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`

`US 2005/0268000 A1
`
`Dec. 1, 2005
`
`resistor 108 of the connected accessory 102. Because the
`predetermined current is a known fixed value, the resistance
`of the identification resistor 108 can be calculated based
`upon the measured Voltage at the Source pin 126. A type
`indicator 138, which is coupled to the voltage detector 128,
`is configured to identify the identification resistor 108 based
`upon the measured Voltage. Further, based upon the identity,
`or the resistance value, of the identification resistor 108, the
`type indicator 138 is configured to determine the type of the
`connected accessory 102. By using the current source 136 to
`generate voltage across an identification resister 108, 110, or
`112, resistance values for the identification resisters 108,
`110, and 112 can be linearly spaced to provide sufficiently
`different Voltages at the Source pin 126 to determine the type
`of the connected accessory. In a Voltage divider method,
`using the voltage source 120 and the voltage detector 128 to
`determine the type of the connected accessory based on the
`divided Voltage at the Source pin 126, the resistance values
`used for the identification resistors need to be spaced expo
`nentially to produce Sufficient Voltage difference among the
`accessory types. For example, Setting the Voltage Source 120
`to be 2 V, the Source resister 122 to be 100 kS2, and the first
`identification resistor for the first accessory type to be 100
`kS2 producing 1 V at the Source pin 126, then the Subsequent
`resistors for different accessory types and the resulting
`voltages at the source pin 126 would be as follows: 200 kS2
`producing 1.33 V; 400 kS2 producing 1.6 V; 800 kS2 pro
`ducing 1.78 V; 1600 kS2 producing 1.88 V; 3200 kS2
`producing 1.94 V. As shown, the voltage difference between
`accessory types rapidly diminishes as the number of types
`increase. To measure the diminishing differences, the Volt
`age divider method would require a high precision Voltage
`Source and high precision voltage detector as well as high
`precision resistors for the identification resistors. However,
`in a current Source method using the current Source 136, the
`resistance values used for the identification resistors can be
`Spaced linearly to produce Sufficient Voltage difference
`among the accessory types. For example, Setting the current
`Source 136 to provide 5 uA and the first identification
`resistor for the first accessory type to be 100 kS2 producing
`0.5 V at the source pin 126, then to produce a voltage
`difference of 0.1 V in the Subsequent accessory types, the
`resistors for the Subsequent accessory types and the resulting
`voltages at the source pin 126 would be as follows: 120 kS2
`producing 0.6 V; 140 kS2 producing 0.7 V; 160 kS2 produc
`ing 0.8 V; 180 kS2 producing 0.9 V; 200 kS2 producing 1.0
`V; 220 kS2 producing 1.1 V; 240 kS2 producing 1.2 V; 260
`kS2 producing 1.3 V, 280 kS2 producing 1.4 V, 300 kS2
`producing 1.5 V, and may extend up to the maximum
`detectable Voltage. By using the current Source 136, the
`Voltage difference among the accessory types does not
`diminish as the number of accessories increase. Further, the
`current Source method does not require high precision
`Voltage Source, high precision Voltage detector, or high
`precision resistors for the identification resistors. Alterna
`tively, the current source 136 may vary the current until a
`predetermined Voltage is measured at the Source pin 126,
`and then the current required to produce the predetermined
`Voltage may be correlated to determine the type of the
`connected accessory 102.
`0009. To reduce power consumption, once the connected
`accessory 102 is identified, the mode switch 134 disables the
`current Source 136 and re-connects the Source resister 122 to
`the source pin 126 so that the removal of the connected
`
`accessory 102 can be detected by detecting a change in
`Voltage at the Source pin 126.
`0010 FIG. 2 is a flowchart 200 of an accessory identifier
`in accordance with the preferred embodiment. The process
`begins in block 202, and presence of a connected accessory
`type 102 is detected in block 204. The presence of the
`connected accessory type 102 may be accomplished by
`monitoring Voltage change at the identification pin 114,
`which is connected to the Source pin 126. Once the presence
`is detected, a predetermined current from the current Source
`136 is provided through the identification pin 114 in block
`206. The predetermined current generates Voltage acroSS the
`identification resister 108, and the generated Voltage is
`measured at the identification pin 114 in block 208, and
`based upon the measured Voltage, the connected accessory
`type 102 is identified in block 210. Alternatively, the current
`Source 136 may vary the current until a predetermined
`Voltage is measured at the Source pin 126, and then the
`current required to produce the predetermined Voltage may
`be correlated to determine the type of the connected acces
`sory 102. Once the connected accessory type 102 is identi
`fied, the predetermined current is discontinued in block 212,
`which reduces power consumption, and the monitoring of a
`change in Voltage at the identification pin 114 is resumed in
`block 214. If the removal is detected in block 216, then the
`process loops back to block 204, and begins again to detect
`for presence of a connected accessory. Otherwise, the moni
`toring of a change in Voltage at the identification pin 114 is
`continued in block 214.
`0011 While the preferred embodiments of the invention
`have been illustrated and described, it is to be understood
`that the invention is not So limited. Numerous modifications,
`changes, variations, Substitutions and equivalents will occur
`to those skilled in the art without departing from the Spirit
`and Scope of the present invention as defined by the
`appended claims.
`
`What is claimed is:
`1. An accessory identifier configured to identify a con
`nected accessory type from three or more accessory types,
`each of the three or more accessory types having a unique
`identifier resistor accessible through an identification pin,
`the accessory identifier comprising:
`a Source pin configured to connect to the identification pin
`of any one of the three or more accessory types;
`a current Source Switchably coupled to the Source pin, the
`current Source configured to provide a predetermined
`current to the unique identifier resistor of the connected
`accessory type of the three or more accessory types;
`a Voltage detector coupled to the Source pin, the Voltage
`detector configured to measure a Voltage at the Source
`pin; and
`a type indicator coupled to the Voltage detector, the type
`indicator configured to identify the connected acces
`Sory type of the three or more accessory types based
`upon the measured Voltage,
`wherein the unique identification resister of each of the
`three or more accessory types is linearly related in
`resistance value to other unique identification resisters
`of the three or more accessory types.
`
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`

`US 2005/0268000 A1
`
`Dec. 1, 2005
`
`2. The accessory identifier of claim 1, further comprising:
`a Source resister coupled to the Source pin;
`a Voltage Source coupled the Source resister, the Voltage
`Source configured to provide a predetermined Voltage
`to the Source resister;
`a presence detector coupled to the Voltage detector, the
`presence detector configured to detect presence of the
`connected accessory type based upon a change in the
`measured Voltage at the Source pin; and
`a mode Switch coupled to the presence detector, the mode
`Switch configured to enable the current Source upon
`detecting the presence of the connected accessory type.
`3. The accessory identifier of claim 2, wherein the mode
`Switch is further configured to disconnect the Source resister
`from the Source pin upon detecting the presence of the
`connected accessory type.
`4. The accessory identifier of claim 3, wherein the mode
`Switch is further configured to disable the current Source and
`to re-connect the Source resister to the Source pin upon
`identifying the connected accessory type.
`5. The accessory identifier of claim 2, further comprising:
`a memory coupled to the Voltage detector, the memory
`configured to Store a detection Voltage measured at the
`Source pin when the presence of the connected acces
`Sory type is detected,
`wherein the change in the measured Voltage at the Source
`pin is based upon a deviation from the Stored detection
`Voltage.
`6. The accessory identifier of claim 2,
`wherein the predetermined current produces a predeter
`mined Voltage at the Source pin, and
`wherein the type indicator is further configured to identify
`the connected accessory type of the three or more
`accessory types based upon the predetermined current
`that produces the predetermined Voltage at the Source
`pin.
`7. Three or more accessory types configured to connect to
`an electronic device, each of the three or more accessory
`types comprising:
`an identification pin configured to receive a predeter
`mined current; and
`a unique identifier resistor coupled to the identification
`pin, the unique identification resister configured to
`produce a predetermined Voltage based upon the pre
`determined current, the predetermined Voltage indica
`tive of one of the three or more accessory types,
`
`wherein each unique identifier resistor of the three or
`more accessory types is linearly related in resistance
`value to each other.
`8. The three or more accessory types of claim 7, wherein
`the predetermined current is equal in value for all of the
`three or more accessory types.
`9. The three or more accessory types of claim 7, wherein
`the predetermined current is a current Sufficient to produce
`a predetermined Voltage at each identification pin of the
`three or more accessory types.
`10. A method in an electronic device for identifying a
`connected accessory type through an identification pin, the
`method comprising:
`detecting presence of the connected accessory type at the
`identification pin;
`providing a predetermined current through the identifica
`tion pin upon detecting the presence of the connected
`acceSSOry type,
`measuring a Voltage at the identification pin; and
`identifying the connected accessory type based upon the
`measured Voltage at the identification pin.
`11. The method of claim 10, wherein detecting presence
`of the connected accessory type at the identification pin
`includes monitoring a change in Voltage at the identification
`pin.
`12. The method of claim 10, further comprising:
`enabling the providing of the predetermined current upon
`detecting the presence of the connected accessory type.
`13. The method of claim 10, further comprising:
`disabling the providing of the predetermined current upon
`identifying the connected accessory type.
`14. The method of claim 10, further comprising:
`re-monitoring a change in Voltage at the identification pin
`upon identifying the connected accessory type.
`15. The method of claim 10,
`wherein the predetermined current produces a predeter
`mined Voltage at the identification pin, and
`wherein identifying the connected accessory type based
`upon the measured Voltage at the identification pin
`includes identifying the connected accessory type
`based upon the predetermined current that produces the
`predetermined Voltage at the identification pin.
`
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`Huawei v FISI
`IPR2018-00465
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