Re: Hmevision ir transmitter

["andy_powell_is" <ukha@xxxxxxx>]

--- In ukha_d@y..., "Ian Davidson" <ian@g...> wrote:
> Hi Andy
> 
> Ok no problems, we will get you sorted.

Thanks Ian :D


> Firstly I do not have homevision and I could do with knowing the 
following
> if you or others on the list know or could point me to the tech 
spec:-
> 
> firstly what sort of o/p does HV produce, is it open collector ?

Yes, "Port A of Homevision provides open collector terminals"


> Does it have any internal pull up resistors ?
> 
> If it does have internal pullups then your circuit may well 
function but not
> by just fitting a switch to the base of TR1.

I don't know the answer to this one :( but looking at 
http://www.csi3.com/hv_p2.htm
near the bottom, there is a table. For 
the ports B and C it says pulled up, for port A it does not mention 
it ... at a guess, based on that I'd say no... but I don't know for 
sure...


> Do you need the LED's on when the port o/p is low or when it is 
high ?

>From what I remember Keith was saying that you set the port low to 
complete the circuit where +5 is provided by the IR jack and the port 
on Homevision provides the ground. So, the LED should come on when 
it's low (and an IR pulse is sent)

> 
> If we can find out these details then I'll try to explain how to 
test it, or
> if not what to change. If all else fails I'll build you a single 
channel
> unit and then all you would need is to copy it.

That would be nice, but it would be better for my skills if I could 
work with you to get the final result. If all else fails I'll gladly 
take you up on the offer..


> Not sure if any one else on the list needs the info but if not your
more
> that welcome to take the mails off list and send to me direct, I'll
leave it
> up to you.

I think that if this ever gets to work :P quite a few people would be 
interested in it.... so perhaps for the moment we should keep it on 
list...

Thanks again for your replies..

Andy

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