MCPC TR-014
Analog Headset Extension forUSB Connector
Version 1.00(E)November 11, 2010

Mobile Computing Promotion Consortium
Technical Committee©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)

Revision History
Date
June 11,2010
November 11,2010

Version1.00
1.00(E)

Description
Base version initial release.
English translated version release.

NoticeThis guideline is English translated version of MCPC TR-014 Japanese version. Though all contents
including technical definitions and values are covered by this document, original technical definitionsand values shall be in MCPC TR-014 Japanese version.

i©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)Published and copyrights owned by:
Mobile Computing Promotion Consortium (MCPC)
Hasegawa Green Building,
5-12 Shiba-Koen 3-chome, Minato-ku, Tokyo, 105-0011 Japan
TEL： +81-3-5401-1935
FAX: +81-3-5401-1937
EMAIL: office@mcpc-jp.org
WEB SITE: http://www.mcpc-jp.org

Confidentiality:
The MCPC Rules and the MCPC IPR Policy Shall ApplyDisclaimer:This document is intended to provide standard specifications, recommended specifications, etc. onmobile computing. Mobile Computing Promotion Consortium (hereafter MCPC) shall not be liable
for any damages or infringements of patents or other rights of third parties arising out of the use ofthis document. This document shall not be construed to grant (a) license(s) under any rights held by
MCPC or third parties.

How we distinguish binary, decimal and hexadecimal numbers：• For binary numbers, we append small letter “b” (e.g. 10b))• For binary numbers, we insert a space after every four bits. (e.g.：1000 0101 0010b)• For hexadecimal numbers, we append small letter “h” (e.g.：FFFFh and 80h)
• All other numbers shall be considered to be written in decimal

Key Words• “May” means that something is recommended or optional at the free discretion of the vendor.
• “Should” means that although something is not essential, it is strongly recommended. When
implementing, the vendor shall take this requirement into consideration and determine whether
this is essential or not.
• “Shall” means that something is an essential requirement. For connectivity and specification
compliance, the feature must be implemented, and is mandatory.

Trademark Notes• Company names, product names, service names and the like described in this document are
generally trademarked or are registered trademarks of their respective owners.
• In general, the usage of ™ marks, © marks, and ® marks has been omitted in this document.
• In general “ Inc., ” “ Corporation, ” “ Co., Ltd., ” have been excluded from company names.

ii©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)Table of Contents
1. Overview ......................................................................................................................... 1
2. References ..................................................................................................................... 1
3. PIN Assignment ............................................................................................................. 2
4. Examples of Accessory devices ................................................................................... 4
4.1 [Mode 1] Stereo Earphone with Mic......................................................................................... 4
4.2 [Mode 2] Monaural Earphone with Mic .................................................................................... 5

5. Notice for implementation ............................................................................................. 5
5.1 Notice for Mobile Handsets ..................................................................................................... 5
5.2 Notice for Accessory devices................................................................................................... 5Appendix A. Charging Extension Mode ........................................................................... 6iii

©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)Table of Figures
Figure 1 Equivalent circuit for USB ID pin ................................................................................................2Figure 2 Example for Stereo Earphone (with Mic) with micro USB connector ..........................................4Figure 3 Example for Stereo Earphone(φ3.5mm) - USB adapter .............................................................4Figure 4 Example for Monaural Earphone (with Mic) with micro USB connector .....................................5Figure 5 Example for Stereo Earphone(φ3.5mm) - USB converter (Charging Extension Mode) .............7Figure 6 Example for Monaural Earphone (φ3.5mm) - USB converter (Charging Extension Mode) .......7

Table of Tables
Table 1 Pin Assignment ............................................................................................................................2
Table 2 Resistance parameters ................................................................................................................3
Table 3 Pin Assignment for Charging Extension Mode .............................................................................6
Table 4 Resistance parameters for Charging Extension Mode .................................................................6iv

©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)

1. Overview
This guideline describes the Analog headset interface via micro USB connector (receptacle connector, type
B or AB at the handset) for both mobile handsets and accessory devices (i.e. Earphones with/without Mic).
The Guidelines contain a set of recommendations, and implementation of those functions and values
described in this document into the handset are optional.

2. References[USB2.0][USB-OTG][USB-BC]

USB-IF, Universal Serial Bus Specification: Revision 2.0, April 27, 2000
USB-IF, On-The-Go and Embedded Host Supplement to the USB Revision 2.0
Specification: Revision 2.0, May 8, 2009
USB-IF, Battery Charging Specification: Revision 1.1, April 15, 20091

©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)

3. PIN Assignment
Pin assignments for each mode are shown in Table 1. The circuit diagram and its parameter are shown inFigure 1 and Table 2 respectively.
When a call button is implemented on an accessory device, RCSW shall be placed in series to the callbutton.
Each operation mode shall be identified with summary resistance value of RFSEL and RCSW
Note: Call button -- Button to answer/end a call with some button press actions (ex; Tap (brief press) orHold (long press) actions)

Table 1 Pin Assignment
Mode 2
Reserved forMode 1
deviceMonaural Earphone with
Stereo Earphone with Mic
maintenanceMic
N.C.／MIC *1)
N.C.／MIC *1)
VBUS
DEAR_L
EAR_(L+R)
D+EAR_R
N.C.
ID
RCSW / RFSEL1+RCSW *2)
RCSW / RFSEL2+RCSW *2)RIDm*3)
GNDGND*1) Vbus remains open when Mic is not implemented on the accessory device*2) When the call button is pressed, the resistance from the ID pin to GND is Rcsw
*3) These values shall not be used for other purposes

Circuit in accessory device
ID
RCSW
Stray
capacitance

RID
SwitchRFSEL

GND
Figure 1 Equivalent circuit for USB ID pin

2ReservedRIDr*3)

©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)Table 2 Resistance parameters
RCSW
RFSEL1RFSEL2
RIDm
RIDr

Resistance [Ω]47k ±5%240k ±5%750k ±5%180k ±5%390k ±5%

To allow the mobile handset to distinguish Tap or Hold of Call button (Switch), the stray capacitance
between ID pin and GND (refer to Figure 1) should be less than 1nF.

3©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)

4. Examples of Accessory devices
4.1 [Mode 1] Stereo Earphone with Mic
Implementation of Mic and/or Call button is optional.
In the configuration of Figure 3, when a Monaural earphone is connected into its φ3.5mm audio jack, theRID (RFSEL+RCSW) and operation mode may not be changed from [Mode 1].

StereoEarphones

Micro-USB

MIC
Micro-USB

SwitchFigure 2 Example for Stereo Earphone (with Mic) with micro USB connector

MIC
φ3.5mm Plug

Micro-USB

SwitchMicro-USB

Figure 3 Example for Stereo Earphone (φ3.5mm) - USB adapter

4©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)

4.2 [Mode 2] Monaural Earphone with Mic
Implementation of Mic and/or Call button is optional.
MonauralEarphone

MonauralEarphone

Micro-USB

MIC
Micro-USB

SwitchFigure 4 Example for Monaural Earphone (with Mic) with micro USB connector

5. Notice for implementation
5.1 Notice for Mobile Handsets
The mobile handsets should also take safety precautions into account as it may also have a battery
charger connected through the Micro-USB connector.
With the Accessory Charger Adapter (ACA) defined in [USB-BC], in some condition, the register value ofthe ID pin may conflict with some mode described in this document. We recommend that developers takecare when designing mobile terminals and consider the implications that ACA may have.

5.2 Notice for Accessory devices
When connecting an accessory which implements Mic in Vbus pin and a mobile terminal that adheres to[USB-OTG], which is not supported in this document, if the call button is held down on the mobile terminal,
the mobile terminal might output 5V on Vbus pin. Accessory developers shall take this into account when
designing the accessory for this case.

5©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)Appendix A. Charging Extension Mode
A.1 Pin Assignment
In addition to the audio connection described in Table 1, when the charging function is supported, Charging
Extension Mode is defined for that purpose. Pin definitions for Charging Extension Mode and their values
are shown in Table 3 and Table 4 respectively.
In Charging Extension Mode, the Mic pin is reassigned for charging. If the handset supports Charging
Extension Mode, suppressing the noise from the Mic pin should be considered.

Table 3 Pin Assignment for Charging Extension Mode
Mode 1aStereo
Earphone andCharging
V_BUS
EAR_L
EAR_R
RCSW /RFSEL1+RCSW*1)

Mode 2aMode 3
Monaural
Charging capable
Earphone andMonaural
Charging
Earphone with Mic
V_BUS
V_BUS
V_BUS
DEAR_(L+R)
EAR_(L+R)
D+N.C.
MIC
RCSW /RCSW /IDRFSEL2+RCSW*1)
RFSEL3+RCSW *1)
GND
GND*1) When the call button is pressed, the resistance from the ID pin to GND is Rcsw (see Figure 1)

Table 4 Resistance parameters for Charging Extension Mode

RFSEL3

Resistance [Ω]510k ±5%6©Copyright 2010 Mobile Computing Promotion Consortium (MCPC)MCPC TR-014 Analog Headset Extension for USB Connector Version 1.00(E)

A.2 Examples of Accessory devices
A.2.1 [Mode 1a] Charging capable Stereo Earphone Adapter
Implementation of Call button is optional. The Mic cannot be implemented into the adapter.
Pin assignment of this adapter is the same as [Mode 1], and when the charging power is supplied from AC
Adapter etc, and output to the USB connector, it shall use [Mode 1a] pin assignment.
Although a Monaural earphone is connected into its φ3.5mm audio jack, the RID(RFSEL+RCSW) and operation
mode may not be changed from [Mode 1] or [Mode1a].

StereoEarphones

AC Adapter
φ3.5mm Plug
Micro-USB

Figure 5 Example for Stereo Earphone(φ3.5mm) - USB converter (Charging Extension Mode)

A.2.2 [Mode 3] Charging capable Monaural Earphone with Mic Adapter
Implementation of Mic and/or Call button is optional.
The operation mode of this adapter is always [Mode 3] whether it is charging or not.
Even if a Stereo earphone is connected into its φ3.5mm audio jack, the RID (RFSEL+RCSW) and operation
mode may not be changed from [Mode 3].
MonauralEarphoneMIC
AC Adapter
SwitchMicro-USB

Figure 6 Example for Monaural Earphone (φ3.5mm) - USB converter (Charging ExtensionMode)7