Re: Embedded interface to HV - C help needed by someoneadventurous

["ian.bird@xxxxxxxxx" <Ian@xxxxxxxxxxxxxx>]

Hi Kevin

This will be interesting there is no doubt about that. There is likely to
be around 16k left over after the Ethernet stack has had it chunk. I can
buffer 8 messages at a max of 1.5k each plus the working variables and
arrays. Codevision is pretty good at telling you when you have overstepped
any boundries.

This device and several of my other projects are all based losely on the
same proven hardware so for the most part there are no hardware issues to
deal with at the moment.

I also implement large chunks or either EEPROM or FRAM depending on the
frequency of writing. Both are pin compatible and use the same I2C
interface so swapping them is a soldering exercise only. I use the hardware
interface available rather than the software one as it is just over 3 times
faster.

I will be wrinting routines to access this linear memory transparently at
some point although you can get quite large chips so this is not urgent.

Ian


Original Message:
-----------------
From: Kevin Hawkins lists@xxxxxxx
Date: Mon, 03 Jul 2006 12:23:38 +0100
To: xAP_developer@xxxxxxx
Subject: Re: [xAP_developer] Embedded interface to HV - C help needed by
someoneadventurous


Hi Ian,

Interesting - I was (once) looking at doing just this too - both to
get a xAP enabled HomeVision controller which a load of people would
like I'm sure and also to have C-Bus lighting control from within HV
(standalone). Having this all embedded would be ideal, my solution would
have used the Rabbit controller as I already have the xAP code running
there for the C-Bus gateway already.  HomeVision makes a great device to
model to the BSC schema in xAP and it's a popular controller in our HA
fraternity so there will be many interested people I think.   My plans
have only changed due to of lack of time and because I no longer use
HomeVison as the core of my HA system having moved to another embedded
controller.   I know a lot of people (inc one well known UKHA'er) are
still interested in the C-Bus side of embedded lighting control from
HomeVision and I might revisit that at some time. I'm sure quite a few
people will appreciate you tackling this :-)

I based all my Rabbit code (with permission) on the xAP C libraries
from Patricks' site and it has worked fine. I had to tweak the code a
little for the ANSI C variant on Rabbit and also to adapt the wildcard
addressing methodology to include sub addressing but that wasn't too
hard. I would suggest this is a great place to start . I'm not sure how
involved the Ethernet stuff is on Atmel but it's fairly easy on the
Rabbit. As you mentioned the things you have to be really tight on are
buffers in the Ethernet stack which consume memory in big chunks and of
course large arrays and strings (same thing in C). For me coming from a
VB background the big learning curve and most frustrating issue was the
different methodology for string handling in C, how I miss mid()   !
I have an ftp and http server in there too but am still battling a
little memory wise to implement the embedded web interface using the
Rabbit web modules. Naming C-Bus groups consumes lots of valuable space.
In practice however very few users have said they would use a web
interface  - they just want xAP.


Kevin


Ian Bird wrote:
>
> Hi all
>
> I am looking at expanding a current project to produce an embedded
> interface to HomeVision. My plan at the moment is to have an Ethernet
> enabled device sitting on the network and it would talk to HV through
> the serial port. I have studied the CSI3 docs and it seems to able to
> do pretty much everything most people would need over serial. I am
> looking for some programming help in C to read in xAP requests and
> then do the serial stuff and send the xAP reply assuming one was
> needed. This would include all the normal xAP housekeeping like
> heartbeats etc.
>
> I can supply the compiler license and some sample programs I have
> written for reference if needed. It is possible someone will have
> some code that can be modified and if so I am all ears.
>
> Any volunteers? Anyone any other ideas? This is driven by the fact
> that I no longer have a PC running near HV and no PC on 24/7 and a
> huge leccy bill so the missus has banned another one hence the new
> project. There is no great time pressure as I have lots on at the
> moment anyway.
>
> This is an embedded project so there are limits in the C programming
> and memory etc. It is 99% ANSI compatible and there is a healthy 32k
> of RAM to play with for the whole program (Ethernet included). This
> essentially means no large arrays etc.





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