AVR-Chat

RS422 driver ought to do it. If its old, it probably has a
75176 or variant. They are a somewhat "heavier" load than
most modern receivers. If the line length is fairly short
(say, up to 25' or so), you don't need to terminate it
quite so carefully. There is no real compatibility problem
with newer drivers (ie, MAX485) and older receivers.

I would connect commons (if not connected thru coax shield)
and the digital pair.

Jim


On Fri, 22 Oct 2004 19:15:23 +0100
 "Doug Locke" <doug@whiteapple.u-net.com> wrote:
> 
> Hello, wonder if someone could point me in the right
> direction regarding an
> old line scan camera that I am attempting to control
> using an AVR. The
> camera supply is +5v and +15v. Basic point is that the
> data rate and line
> rate signals are just specified as differential line
> driver signals and
> shown as having a +ve and -ve connection and a comment is
> made that for slow
> speed access the -ve pin could be biased with +1v and a
> TTL signal applied
> to the +ve pin. Would I be okay in using a JK flip flop
> wired to toggle and
> use the Q, Q bar outputs,  maybe just connect each pin to
> the AVR and toggle
> the lines or should I use say a RS422 driver,. Afraid
> that I have no
> experience of differential line drivers and appreciate
> any help in this
> area.
> Doug.
> 
> 
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Hello, wonder if someone could point me in the right direction regarding an
old line scan camera that I am attempting to control using an AVR. The
camera supply is +5v and +15v. Basic point is that the data rate and line
rate signals are just specified as differential line driver signals and
shown as having a +ve and -ve connection and a comment is made that for slow
speed access the -ve pin could be biased with +1v and a TTL signal applied
to the +ve pin. Would I be okay in using a JK flip flop wired to toggle and
use the Q, Q bar outputs,  maybe just connect each pin to the AVR and toggle
the lines or should I use say a RS422 driver,. Afraid that I have no
experience of differential line drivers and appreciate any help in this
area.
Doug.

At 01:15 PM 10/22/2004, Doug Locke wrote:


>Hello, wonder if someone could point me in the right direction regarding an
>old line scan camera that I am attempting to control using an AVR. The
>camera supply is +5v and +15v. Basic point is that the data rate and line
>rate signals are just specified as differential line driver signals and
>shown as having a +ve and -ve connection and a comment is made that for slow
>speed access the -ve pin could be biased with +1v and a TTL signal applied
>to the +ve pin. Would I be okay in using a JK flip flop wired to toggle and
>use the Q, Q bar outputs,  maybe just connect each pin to the AVR and toggle
>the lines or should I use say a RS422 driver,. Afraid that I have no
>experience of differential line drivers and appreciate any help in this
>area.

You'll need to know how the data is encoded, but you certainly can do a 
"rude and crude" conversion to single ended like that.  You may need to 
ground the other conductor, depends on how they implemented the interface, 
but I would guess it's about 90% that you will.  Otherwise, it would really 
be a three wire connection, with S+, S- and ground, but "ground" in an 
industrial environment can be pretty amusing.

You'll be better off to go through an "official" conversion circuit though.