Re: Serial protocol questions

["g8kmh" <lehane@xxxxxxxxxxxxxxxxxxx>]

I've dropped my response in below.

Lehane

--- In ukha_xpl@xxxxxxx, "Neil Wrightson" <neilw@n...>
wrote:
> Hi Guys,
>
> 1) I'm all for a combined project.
>
> 2) I don't want to start another mine is better than yours
discussion, but,
> I use AVR's :) I have a great compiler AVRCo with true multitasking
etc

To some extent it is irrelevent to most end-users. Few are going to
change code, some will want prog'ed devices and most a kit (or at
least PCB and CPU).

The protocol outline is doable across a wide range of devices, indeed
it needs to be interoperable.

>
> 3) I think that a dedicated 485 network controller will be
required. I think
> the 485 comms will probably run about 38400 baud.
>     A 16MHz AVR will happily look after this.
>     The network controller will pass and receive all state changes
to the PC
> as well as heart beats for each device.
>     Comms to the PC could be 9600.
>

A separate controller has some advantages of redundancy and
interfacing with Win* or *nix.

With xPL not on the wire then heartbeats can be different internally
to externally.

Presumably the host software will do the device/instance id->node
number conversion and the device/instance config?


> 4) I envisage that there be at least two types of room controllers
(Perhaps
> we should start by settling on some names for these things)
>     a) Bedroom/kitchen/Living area Controller wish list
>         Display,
>         Personnel Switches for lights, sound muting etc,
>         Data entry method, Set room alarm clock time etc Sleep time
for
> lighting etc
>         IR Transmitter, Turn telly off when I fall asleep in bed,
turn
> ceiling fan off etc etc
>         Personal ID method
>         Sound
>         Movement sensor interface
>         Switch inputs for door & window reed switches
>
>     b) Basic room as in garage/toilet/bathroom wish list
>         Personnel Switches for lights etc,
>         Sound
>         Movement sensor interface
>         Switch inputs for door & window reed switches
>         Note - This is to be a cheaper version, no display only
beeper for
> sound alerts, maybe a IR receiver for configuration ??
>
> Hardware Solutions for above
>         Display,
> 16*2 LCD with LED backlight OR maybe a small graphic LCD, could
display
> small icons for
>
> you have email, voice messages, phone callers etc.
>         Personnel Switches for lights
etc,                             2..4
> Tactile switches I.e. small PCB mount
>         Light Control
> either 240V relay or triac, triac allows dimming, great for those
wee stops
> in the night
>         Data entry method,
> Universal TV remote. I can currently decode Sony or RC5 signals
>         IR Transmitter
> IR led on controller as well as capability to add an external IR
led else
> where in the room
>
> for better coverage if needed, I.e. Living room with external LED
for Stereo
> etc.
>         Personal ID method
> Dallas 1 wire ibutton, A lot cheaper & smaller than RFID!
>         Sound
> 2 Types, 1) Standard beeper. 2) Optional 1W speaker with sound
relaying from
> controller Pc
>
> Probably a separate optional PCB.
>         Movement sensor
interface                                    As
> suggested either a integrated unit actually on the controller or a
separate
> security PIR
>         Switch inputs for door & window reed switches
Standard style
> of inputs on a micro 5..12V tolerant.
>
>         Power Supply and Signal
>             I suggest that we use CAT5
>             Power - 2 Pairs 1 pair for 0V and one pair for +24V.
>             Comms Signal  - 1 Pair
>             Audio from PC - 1 Pair
>             If we try to use the standard pin outs for power over
Ethernet
> and data signals, nothing will be damaged if
>             a wrong device is plugged in somewhere.
>             Although, I did see these devices as being panel
mounted on the
> walls.
>
Mmm!
I'd caution against making the devices too complex. Better have 10
types (smaller/cheaper) than 1 do-everything and they are likely to
see the light of day faster. You can always put two/three/four in one
box.
So I'd go for:
1 n-way DC input (maybe analog) variations can include on/off,
momentary, dimmer action, etc.
2 n-way DC output (maybe PWM on some for LED's) variations - opto,
SSR, etc
3 LCD display driver
4 RFID (...and RFID to me is EPC/ISO 18000)
5 Universal IR (UIRT on 485)
6 Dallas touch and/or one wire sensors
7 MSR (Track 1/2/3)
8 Bar Code Reader (UPC/EAN/ITF/Code 39)
9 Analog input/output (0-5/10V)
10 ....

Agree on the power to the unit, although 12-15V maybe sufficient as
the power consumption is going to be pretty low on most.
Not sure about the audio..I think that belongs on Ethernet in the
digital domain. I guess you're looking at voice/audio feedback but
would you want output from every device? Or would you command each
amp on?








xPL Links: http://www.xplproject.org.uk http://www.xplhal.com http://www.xpl.myby.co.uk
To Post a Message: ukha_xpl@xxxxxxx
To Subscribe:  ukha_xpl-subscribe@xxxxxxx
To Unsubscribe:  ukha_xpl-unsubscribe@xxxxxxx