AVR-Chat

Look in the Projects archive of avrfreaks.net. Among others, the TWIRP project.


--- In AVR-Chat@yahoogroups.com, "Dave McLaughlin" <dave_mclaughlin@...> wrote:
>
> Hi All,
> 
>  
> 
> I originally posted this on the Codevision AVR list and then realised it was
> not the right place so I searched to find the best place to post it and
> found this list instead so I hope it is the correct place to post?
> 
>  
> 
>  
> 
> I am developing some home automation gear for my apartment. When I lived in
> the UK all the heating was controlled over CAN bus but now that I am in the
> Far East I only have air con to deal with. The problem is that I can't run
> cables here as I live in an apartment block and most of the walls are
> concrete with a few exceptions. What I have developed is a small module
> based around a www.display3000.com ATMega2561 based board with TFT display
> and putting this on my own motherboard with a Zigbee Pro radio module. 
> 
>  
> 
> The radio part is easy and working.
> 
>  
> 
> The part that I am trying to improve upon is the Infra Red input and output.
> Doing a search I can find loads of RC5 decoding but the problem is that the
> aircon units here are all National (Panasonic) so the infra red code is very
> different. I also need it to work with other aircons in the future. Using
> the logic analyser it appears to be around 30+bits for each button press.
> There doesn't appear to be a discrete ON/OFF, rather it causes the unit to
> toggle ON or OFF at each command transmission. The output from the Infra Red
> receiver is connected to an interrupt pin. I also have an infra red emitter
> connected to one of the timer output pins via a drive transistor.
> 
>  
> 
> The code is designed such that the user selects from a menu, the programme
> mode and then points the original remote control at the receiver and the
> device then reads the pulse stream. I have developed some code to look for a
> start from the remote and using one of the timers, time the high and low
> times and store these in memory.  Not very efficient on memory as I am using
> around 120 bytes to store the 16 bit time and the HIGH or LOW state. I have
> not tried using an 8 bit timer and this was next on my list. I could store
> the HIGH or LOW in the top bit of the 16 bit value and this would reduce the
> count by about 30 bytes.
> 
>  
> 
> For transmission, I setup a timer for a 38Khz output and then just switch
> the PORT bit on or OFF based on the original times recorded during the
> reception phase.
> 
>  
> 
> As for ON or OFF I have to keep a flag in the code to know what state the
> unit was last in. This works fine until my partner switches the ac with the
> original remote. Something I am still trying to train her for  :o)
> 
>  
> 
> I am still looking at a way to do this more effectively as I would like to
> be able to do temp control from the unit also. At present, all it does is
> switch on or off the aircon. I would need to be able to decode the infra red
> bit stream and so far have not been able to find anything on the net that
> describes the encoding scheme used. 
> 
>  
> 
> I would appreciate any thoughts you all might have on how I could improve
> this system? I am not looking for help with the code as I can do that
> myself, what I am looking for is some ideas on how to improve what I have
> attempted so far.
> 
>  
> 
> I have built 2 systems so far and have 4 aircons in total to control.
> 
>  
> 
> PS. These little TFT displays are well cool.
> 
>  
> 
> Regards
> Dave.
> 
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