rs232 to TTL (rca ?) conection ?

[maybeoneday]

Hi all,
        calling any electronics people,

I have a Cambridge Audio 540R v2 which I'm wanting to control via serial port on pc, using LinuxMCE.
Acording to CA's tech support the rs232c port on the receiver is for software updates only (540R v3 does support), and having tried that option (they originally told me it was posible)...Dead end ? ...no ..the receiver has a Custom Install Bus which appears to be a normal rca audio connector.

The manual states............


"The 540R V2.0 features a Control Bus input that allows un-modulated
remote control commands (positive logic, TTL level) to be received
electrically by the unit. These control commands are typically generated
by custom installation (multi-room) systems or remote IR receiver
systems. The Control Bus socket is colour-coded orange.
This unit features 'direct' IR/Control codes as well as toggle codes for
many of their features to simplify programming custom installation
systems. Special direct On/Off commands can be accessed on the
supplied remote control for teaching into C.I. systems as follows:
1. Press and hold the Standby/On button on the remote control. The
remote first generates it's standby (toggle) command. Keep the
button held down, after 12 seconds an AV receiver “On” command
will be generated. If the button is kept held down for a further 12
seconds, an AV receiver “Off” command is generated.
Repeat this procedure with the Mute, Sub On/Off, Stereo Mono and
Tuner AM/FM buttons to send On/Off commands. The Tuner AM/FM
button also provides unique FM and AM commands to allow switching to
a specific band."

and also

CONTOL BUS INPUT

"Opto isolated, TTL positive logic,
Unmodulated"


I've googled like hell all day , and from what I can gather , this should  be possible,but all the references
are either way over my head,/too vague to be of any use/ or are involved with both sending and receiving thro micro controllers/usb


So, my questions,
1) would it really be an rca phono plug?
2)if so would it be possible to directly connect via com port on pc,and if so which pins ?
3) any potential problems?



any help / clues on where to start greatly appreciated,
tia
Ian

ps..please...KISIS...keep it simple, I'M stupid.

[hari]

ok, so first that remote is able to emit discrete on/off signals to be learned and used with any automation system.

Second, as infrared light propagation in rooms can be unreliable (interference, blocking line of sight, whatever), some HIFI components have those control inputs. This is completely different from a rs232 port, it accepts the modulation of an IR signal as TTL. So if you have a device that supports IR "blasting" via external emitters, you can also use a RCA cable instead of an emitter and connect it directly to that port.

best regards,
Hari

[PeteK]

The RS-232 voltage levels as defined in the spec are up to 15V, while TTL only allows up to 5V.  While in reality PC RS-232 drivers typically aren't driving up to the 15V level, they should be going negative (below ground), which may be a problem for your equipment. My guess is that it will probably work. However, to meet the spec, Like Hari suggest I think it would make sense to use a Global Cache GC100's IR outputs.  I'm not 100% certain, but it looks like it's driving the IR emitter with TTL signalling.  As for RS-232 pinout, pin 3 is the output and pin 5 is the ground.  Connect 3 to the pin and 5 to the barrel of your RCA plug for a standard config, unless your manufacturer says otherwise.

[hari]

i'm not aware that we have a DCE device that supports "IR strobing" over the TX pin of the serial port..

[PeteK]

It would take a custom device and some Ruby (or C++) coding and I think it could be done.  However, the more we talk about it, the more I think the GC100 is the way to go.

[hari]

maybe the dumb serial driver from lirc could do the trick, but I'd also recommend the GC100 or some other supported USB IR blaster device..

[maybeoneday]

Thanks for the replies guys,

am trying   via  usbuirt,  or I will be, once I  get it to learn/blast  !

many thanks,
Ian

[maybeoneday]

Hi people,

IT WORKS

usbuirt  |  stereo to 2xmono adapter --->ms blaster bug
                                                ---->3.5 to rca adapter--->  rca to rca cable-----CI bus input

----have only completed a couple of codes, as it's a bit of a performance learning the discrete codes,
but will document the  whole process on wiki shortly,

Hari,  do you have to dry your feet when you've finished walking on water   ??   

many thanks,
Ian
ps getting the usb uirt to learn is a bit of a bitch

EDIT  most codes scraped ,  and available - PM me
Ian

[hari]

IT WORKS

cool!

Hari,  do you have to dry your feet when you've finished walking on water   ??   

I usually hover 10cm above :-p