Re: Rosetta progress report

[nobody@xxxxxxxxxxxx (Dave Houston)]

I use a separate oven dedicated to soldering and no longer have a wife (gave
up after 12, figured 13 would be unlucky).

As I think I noted earlier, modifying the BX24-AHT firmware will come after
I finish roZetta and after I port the code to the ZX-24. To be clear about
my priorities...

1. roZetta (which will use a ZX-24)
2. port BX-24 code to ZX-24 - can be used with existing BX24-AHT boards
3. update BX-24 code for existing BX24-AHT users

I will include your escape mechanism in roZetta (#1) and will try to
remember it for #2.

#3 requires adding an external EEPROM to the BX-24 "chip" and a major
rewrite of the code. I may not last that long. The existing firmware works
well (Manual documents features) but uses all but about 10 bytes of the
EEPROM. I have no plans to do anything with it until finishing 1 & 2.

I think roZetta will probably suit your needs better than the *X24-AHT
although it will require that you use a modified MR26A for RF input.

The main failing of the BX-24 (other than insufficient EEPROM) is that it
only has only one software UART. While it can be reassigned to different
pins, it can only use one pair of input/output buffers. This means that only
one of the three secondary serial ports can be full-duplex (almost full as
it goes deaf when the UART is switched to the other pins). Since the CM11A
keeps repeating its "data available" poll until there's a response, nothing
is lost during the brief excursions of the UART to other pins but it limits
the usefulness of the other ports to tasks where the attached devices can be
polled. The ZX-24 makes about 10K of EEPROM available and has 4 full-duplex
interrupt driven software UARTs. (And the developer of the ZX-24 is far more
open to suggested improvements than was Jack Schoof who developed the
BX-24.) I still have some work to do to adapt the code to the ZX-24 chip.
When I get it adapted I plan to publish it as an Application Note on the
ZBasic site. Anyone who wants can take a stab at modifying it for their own
purposes whether benign or nefarious.

The problem roZetta has regarding collisions is totally different from any
associated with the RR501. The RR501 sees the powerline in realtime while
anything listening to a TW523 only sees it on a delayed (and part-time)
basis.

I had just recently shut down my web page so I wouldn't have to update and
maintain it. I'm afraid roZetta will require a web page to explain its care
and feeding so I'll try to get that setup while I'm waiting for the 2414S
and UPB gear that Bruce is loaning me.

I've also designed a board that uses the ZX-40 (and optionally can use the
xPort) that more or less duplicates the basic concept of the *X24-AHT but
with more EEPROM and more I/O pins (8 ADC, 6 DIO). It was while designing it
that I realized it would (with some changes) make an excellent universal
translator which led to roZetta. roZetta uses the ZX-24 because it was
easier to make a plug-n-play version using it and because roZetta doesn't
directly interface with an RF receiver.


"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>
><stuff snipped>
>
>> The easiest way to build DIY boards with SMT components is with solder
>> paste, a hypodermic dispenser and a toaster oven.
>
>You've just spelled out the recipe for divorce, at least in my house.
>Science projects may not involve the kitchen and I'll admit, there's good
>reason for that after I burned a hole in the Formica with a pocket torch.
>
>> The oven is overkill for the MPX4115 mod. A dental pick to hold them in
>> place while tacking them with a 15W iron works quite well.
>
>I've come to realize why I like assembling PC's from parts.  The new AMD
>CPUs have 754 pins but they all slip like a greased pig into the ZIF socket.
>Of course the rest of the motherboard is just crawling with lady bug sized
>SMT's with more leads than a centipede has feet.  Fortunately, they rarely
>require anything more complicated than replace fairly large "through the
>hole" power capacitors.
>
>Could I use the BX24-AHT (Bixtoforat?) and modify it to implement the escape
>key method of all house control?  Or would it be easier to modify the TM-751
>the way Dan L. did?  I was just looking at his code for the modified
>transceiver and came across this block, which might offer some clue how to
>handle your problem with collision detection:
>
>"; Wait until there have been at least 4 half cycles with no received
>; carrier and there have been at least 6 half cycles since the end of
>; any received message (including our own).  This does not necessarily
>; require any delay since the routine examines the history in the
>; receive buffer.  A gap of 4 half cycles guarantees that we will not
>; step on the middle of some other transmitter's message.  A gap of 3
>; would be sufficient, but 4 is more symmetrical.  The 6 half cycle gap
>; guarantees that we do not "tailgate," risking having our message taken
>; as a repeat of some other sender's.  Another interesting possibility
>; would be to wait for 7 half cycles on the first of each set of 6-spaced
>; transmisions.  If all transmitters did this there would be no risk of
>; synchronized collisions on any message after the first."
>(c) Copyright Daniel D. Lanciani 2002
>
>From: ftp://ftp.danlan.com/ftp.danlan.com/homeauto/x1002.txt
>
>This stuff really makes my head hurt.  I'm going to go watch "This Old
>House" to clear my poor addled brain.  I thought C-MAX was hard to follow.
>I just can't make any sense of ASM files.  I feel dumb.