The Sony Unilink System
A technical overview
presented as a one-act play in a not-quite-Shakespearian
Style (21st century translation provided at the end)
Metrulio, a musician
Antius, a tradesman
scene: a carriagehouse
Antius is present at opening, attending to small labours in the
Enter Metrulio carrying a parcel under his arm
Metrulio: Well met, Antius! How are thee to this fine morrow?
Antius: In quite good humour, my friend. What doth thou tarry
with in thine arms?
Metrulio: Thou art a keen observer. Come and behold this
exceedingly excellent system I have purchased for my carriage yet this
Antius: A new Head Unit, do I declare, Metrulio!
Metrulio: Aye, aye.
Antius: And how canst though afford it, thy scurvy dog? Art thou
not still in debt unto me for 30 ducats from out visit to the tavern
a week prior? Dost thou shill me?
Metrulio: Nay, nay, in truth I do not, for I am good for it all.
I did hence purchase this for a very pittance of a sum for t'was an
open box clearance item -- I would be less than a man should I have not
leapt on this opportunity as though a tiger on prey.
Antius: Not so much a tiger a a wee thrice-bred feline.
Metrulio: Curb thy noisome verbiage and join thee in my
regalia! This shall compliment us both, for I shall be freed from the
bondage of using a Cassette Tape Adapter to get my music from my Mp3
Player outword twixt mine speakers!
Antius: Though dost expect me to believe, nay accept, that you
didst afford a Stereo with Auxiliary in on a meager income such as
Metrulio: No credit is given to mine actions, little brother?
Cease thy pander and view these, and then salt thine hat and eat it.
Metrulio unpacks the head unit and shows the rear side to
Metrulio: Art thou the town jester, or canst though see these two
dulcet darlings labeled so elegantly as "Bus In Left" and "Bus In
Right"; Never was such poetry issued from the lips of man nor
Metrulio swans about in a euphoric state for a moment.
Antius: Metrulio, I say, Metrulio.
Metrulio halts abruptly.
Metrulio: I am present, you strumpet. Speak thy mind or shut
Antius: Art thou a fool?
Metrulio: Art thou a fiddlers elbow?
Antius: I say, art thou a fool, you great pillock?
Metrulio: I should say not, yet I will still cause thee great pain
Antius: Thou art still a fool, and a penniless fool hence.
Metrulio: Is there a point to thy ends here, or dost thou simply
delight in the hearing of thine own words?
Antius: Fucketh thee.
Metrulio: I shall run thee through, knave!
Metrulio draws his sword half from scabboard in a menacing
Antius: Let thine hand thy manhood leave be, and I shall explain
why though art a torpid potatoe.
Metrulio: I shall run thee through! See if I don't!
Antius: Give calm to thyself, lest thy do shat theeself.
Metrulio looks flusted.
Antius: didst thou actually think in thy infantile mind that thou
wouldst pur'chase a fly stereo with Auxiliary inputs for thy meager
wage? Nay, this is a Sony so surely though hast be much deceived.
Metrulio: Strewth! How now?
Antius: Bring thine eyes hither.
Antius takes head unit, points to a spot on the rear for Metrulio to
Antius: This is a Sony Unilink port and is the key to thine
eventual woes, like a storm on the horizon.
Metrulio: I see not how. Pray, what is a Unlink port, friend?
Antius: The port itself is a simple 8 pin DIN connector that is
found on many Sony stereo systems, amplifiers and other electronics.
It is a multidrop serial bus used for controlling devices and
retrieving data from them. It is used to daisychain multiple devices
together simultaneously -- thou can have up to 7 CD changers in one
Metrulio: So 'tis a remote control system, eh?
Antius: Moreso then that; not only does it control, it also
returns data and polls devices on the bus.
Antius moves closer to Metrulio.
Antius: You see, unless a device is connected to the Unlink bus,
the Aux In lines in the head unit will not accept input; So without a
special XA-300 Auxiliary Activator, though art mightily screw'ed.
Metrulio: Nay! I am not as thick as a stunted Frenchmen! I can
simply built a pigtail and jumper the sense lines on the connector! I
am still victorious!
Antius: Aye, ye may think that, and thee would be correct is this
weren't a Sony deck.
Metrulio: Indulge me?
Antius: Not without a stiff drink and a blindfold.
Metrulio: Nay, thou clodpoll! Indulge me as to why mine
brilliant scheme won't work.
Antius: Ah. Well, the head unit does not detect devices based on
a close circuit and sense pins. Instead, the devices on the bus must
announce themselves using the S-Link protocol.
Metrulio: The devices on the bus must be intelligent! That's..
Antius and Metrulio: (Together) EVIL!
Metrulio: Wait. This protocol as you say cannot be to complex,
Antius: Nay, S-link is not too demented. Not half as thee.
Metrulio: So, could one not talk to Wozniak the Geek and get him
to build a mystical device to emulate a Unilink device?
Antius: Jumping ahead of me thou are. There is the 'Gnunlink'
project with has code and schematics for making an Auxiliary input
activator using a PIC microcontroller -- All thou'est needs is a few
rudimentary parts, a PIC chip with 8 I/O lines and a PIC programmerer.
Metrulio: I mayest still come out on top.
Antius: For once.
Antius looks pensive.
Antius: But if thou canst hack together a box, thou cast still
putchase an XA-300 Auxiliary adapter from Sony for $100, or the
Slink-e third-party activator for $250.
Metrulio: The non-Sony is more expensive?
Antius: Aye; like the Gnunilink device, it not only activates the
aux inputs, but also allows signals to be sent to and intercepted from
the head unit allowing your Mp3 title to be displayed on the LCD of the
deck in they carriage.
Metrulio: Most excellent. Tell me more about the connector
Antius: As I said before, it is an 8-pin DIN style connector,
though only 7 pins are used; they are Reset, SIRCS (for remote control
host commands), Clock (for signal timing, about 8mHz), Data, Bus On,
Constant +12v for memory and the necessary common ground wire.
Metrulio: The plug itself looks like private knowledge? How doest
I obtain a unilink plug to use in the Gnunilink project?
Antius: Though can either talk to a Sony representative and get
one directly from them, or the easier way is to get a Unilink extension
cable and use the male end of it to built your box.
Metrulio: I am not fucked. Huzzah.
Antius: Huzzah. Though doest still owe me 30 ducats, though.
Metrulio: Gaze upon my extended middle finger.
Metrulio gives Antius the finger.
Unilink is a stereo peripheral connection system developed by Sony and
used in some car audio systems (and to a lesser extent home systems) from
Sony, Kenwood, Denon and a few others.
Physically it is a round DIN style connector with 8 pins (with 7 pins
actually used), looking a lot like an ADB connector. One end of a
cable is plugged into the Unilink port on the "Host" unit (i.e.
stereo), and the other end is plugged into another device. That device
will usually have another downstream port to plug into another device so
you can have up to 7 devices all controlled from the Host. This can be 7
CD Changers, MD Players, VCRs or any combination of anything that
has a Unilink interface.
The audio itself is handled via a separate audio connection usually
called "Bus Left/Right" which sends the audio signals from the devices on
the chain to the upstream back to the head unit, this means that any
head unit that has a Unilink port will have Bus Audio In ports in the
form of two RCA connectors.
One would assume that because it has audio in connectors, it can just
accept audio right out of the box; this is not so. The audio inputs
themselves are not activated unless there is something plugged into the
Unilink port on the unit; And don't think you can just make a pigtail
jumper to make it think there is something, either -- it won't turn on
those ports unless it's a valid Unilink device.
This is because Unilink devices use the S-Bus protocol to
communicate with each other; when the stuff is turned on the head unit
polls all the devices on the chain and only accepts audio if if it gets a
valid response in the protocol it understands.
There are ways around this; the first is to use a Sony XA-700
Auxiliary Activator; it is a Unilink device with two RCA inputs and
nothing else. You plug it in to the Unilink bus, then plug your device
into it and then you can input audio from any source; the downside it it
retails for $99 USD.
Two non-Sony options are the Slink-e for $250 and a Gnunilink
device for the cost of parts. The Slink-e is an Aux activator that also
talks to the bus in a way that you can make text show up on the Head
units display using serial data from a computer. The Gnunilink system is
a set of code and schematics to make your own Activator using a PIC
chip and some Free code, but requires PIC programming hardware and a
Unilink connector (which you can get by buying a Unilink extention cable
and cutting off the end you want).
The connector itself is an 8-pin (7 used) deal. Their functions are
not too complex: Reset, SIRCS (S-Link Interface Remote Control
System, for remote control host commands), Clock (for signal timing,
about 8mHz, not the time of day), Data, Bus On, Constant +12v for memory
preservation and a common ground.