Your Opinions please

["Ian Davidson" <ian@xxxxxxx>]

Hi all
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Firstly a warning this is likely to be a long post.
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Secondly an update on the x10 replacement. It has been proceeding very
slowly over the last couple of months for various reasons, however I
have the computer interfaced finished and one lamp module build up in a
din module that is working except for a few software bugs. I have
adapted my PIC programmer and made all the units flash upgradeable via a
small programming socket. I am now stuck until the larger size PIC is
available in its sm format which should only be a few more days. Thanks
here to Li who let me have a couple of the DIL type so I could carry on
a little further. If anyone is interested I can stick some photo=92s
somewhere.=20
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Ok now the questions. I do not know if to continue with this design as I
had originally planned. My requirements are:
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Must have full status feedback both when operated remotely and if
applicable locally.
Must be quick.
Must be easy to integrate into things we want to automate.
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Having seen the post the other week on the z-wave system has got me
thinking again. I have contacted them and signed an NDA but I am still
in the process of finding out all the details. If the modules are cheap
enough then it may be to design around it to have the usual lamp
modules, appliance modules, switches etc we could add this to what ever
we wanted if the price was right! If the price is too high there are two
more options. I have now info on some IC=92s which will basically make any
unit wireless on the license exempt 868Mhz channels, there are also
modules you can buy utilising these IC=92s ready for integration into
other products. To give some idea of prices the ic=92s are about $10 each
but require other components and a high quality PCB, the modules are
pre-done but cost about $37 each. At the moment I can not decide which
route to go down. Due to my work I have full access to all the equipment
required to test and calibrate any wireless unit up to 1Ghz. Anyway some
advantages/disadvantages.
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Data rate.
Wireline =3D 2400 BPS
Wireless =3D various but would probably use 19,200. (speed trades off with
the RX sensitivity)
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Size
Wireline =3D Larger due to the size of mains rated components and safety
components
Wireless =3D less than 1=94 square by a few mm for the radio module
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Range
Wireline =3D Tested at over 200m with other devices on the line.
Wireless =3D will be less in building, but option of repeaters at slight
cost to speed.
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Cost
Wireline =3D Main IC is =A39.00 plus many other components, the larger
main=
s
rated parts can be over =A31 each
Wireless =3D Slightly more expensive but fewer other components
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There are other advantages and disadvantages. With wireless imagine a
light switch using a wireless module fitted in a metal backbox with a
brass faceplate range would be in cm=92s. With wireline as we know other
devices or many wireline devices in the same place can cause the signal
level to drop to un-usable levels.
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One other point is the protocol used. I should have mentioned that
technically even my modules now could simply be reflashed to work with
either XAP or XPL. At 2400 BPS these protocols can be a little heavy but
if we go to 19,200 then it does mean they may become an option. However
comms over either wireline or wireless do need to be acknowledged and
have a minimum of a 16bit CRC. Forgive me for not keeping up and knowing
if this is now possible with either protocol.
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I should point out that this is not aimed at any commercial interest. I
want to automate all my lighting and many other devices but find X10
slow and no status available and other products ( C-bus) to expensive. I
will post everything I do and if others are interested we can see what
routes to take.=20
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I really am interested in what you all think and would appreciate any
comments on what you think is the way HA should go forward. What type of
device would you prefer wireline or wireless, not sure if it is possible
for a poll to be set up for this.
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Thanks for reading if you got this far and sorry for the very long post.
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Ian D=20
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