Preventing Random X-10 Code interference...

I was not sure whether units would respond to a second code or whether it was there to confirm the correct reception of the first code.

There's clearly a collision problem but it's only intermittent. Once I figure out how to use the signal dissect mode I can analyze what's happening. That isn't going to be fun with just a two-line display. If only they had added a output port of some kind. Do you think it's possible to "tap into" the Monterey's LCD and save the readings somehow? AFAIAC, it's a big honking limitation - far worse than a top end of 4.0v or its tendency to spit up BSCs. Thanks again!

-- Bobby G.

[snip]

Both require soldering.

Most phase coupler/repeaters repeat only the second copy so the off phase will only see one copy.

The receiver has no way to know whether it is seeing the first or second or Nth copy. It can only look for 1110 followed by a valid code.

I have no idea whether it's possible to hack the Monterey - $300 is a little too dear for experimenting. It would be better to start from scratch and design an inexpensive circuit that would output via RS232 or USB. That's still on my list but I may never get to it.

Did you ever get the screenprint I sent? It showed a code fragment from a deliberately induced set of collisions. Two palmpads both set to B sending "1" on and "3" on simultaneously produced a single command for the M housecode. I'd sure love to figure out why we get so many reports of phantom codes.

Now that you've taught me how the signal is Manchester encoded, I am in agreement that it's highly unlikely that phantoms codes are generated by noisy appliances. I do believe that there are powerline "events" that can trigger X-10 transmitters simply because because unplugging and replugging certain modules puts lots of BSC's on the powerline, at least according to the Monterey. Something's causing people to post here, week after week, that they are seeing phantom activations, or more popularly, phantom activity log entries.

It's hideously hard to try and map out even a single command on the Monterey because of the tiny readout.

Well, here's to your good health and the hope that you'll eventually get around to it. A marriage of the Lynx's ability to show each frame and bit, the Monterey's ability to read the voltage of each bit and Activehome's logging ability would be sweet.

-- Bobby G.

I got the screenprint but trying to interpret it gave me a headache. ;)

A minor but necessary quibble: It was two transceivers that created the collision.

With the Monterey reporting every 1110 sequence that isn't followed by a good code as a BSC, any burst of ~120kHz that lasts for 3 or more half cycles will create 1110 at the first clear half cycle.

Many people jump to the conclusion that an on/off event means there are valid codes on the powerline but this is seldom the case. I always try to determine whether or not anything is logged and then look for a transmitter when there are real codes. However, with the proliferation of manufacturers who have their own feature sets, we may see more and more two-way modules that will generate codes after some transient event.

That's why I never recommend it - it just seems far too costly for what it does.

My plan has been to output 3 bytes per half cycle. They would give the amplitude (8-bit resolution) at ZC+250µS & ZC+900µS as well as the number of rising edges between those points. All would be logged to a file with a timestamp for the start of each sequence. Logging would stop once 3 idle cycles were seen and resume on a new line at the next "1" seen. Software would be able to reconstruct the sequences. Even the average frequency of the carrier or noise could be calculated.

Sweet! It would be nice to have one! I'm sure there's nothing I can do to help because of my limited experience but I have been looking at various tutorial sites that might be helpful. I was wondering what the TW523 can do at the very raw level because the LynxView software ran from the standard Marrick Lynx interface.

I'm not sure if I am understanding what I've read correctly but it seems that the various clones of the TW523 can be made to output useful information to a log file - not with the detail that you're proposing but with a great deal more detail than anything short of a powerline analyzer. Would TW523 make a good base for building on something that could do more Monterey-like analysis at the bit level or does it require really starting from scratch? I like the idea of hacking a TW523 because it seems that it's UL listed and the outputs and inputs to the PC are optically isolated.

In fact, while looking for tools to work with the TW523 I came across this article:

which talked about something we had discussed previously:

"As you see here, the START code takes 2 cycles, the HOUSE code 4 cycles, and the KEY code 5 cycles. This is the 11 cycle message segment. One complete command consists of the message segment sent twice, taking 22 cycles of power to send. If the TW523 was receiving this 22 cycle transmission, data will only be sent out to the DS5000 during the second message segment. The proprietary chip inside the TW523 is comparing the first message segment with the second segment as it is received and presents data to the DS5000 during this second segment. This comparison is made to validate the X-10 command, and that it wasn't garbled with noise during transmission."

It this 1st/2nd command comparison something unique that they are doing to interface with the DS5000 microprocessor or what? I'm convinced that wall switch modules from X-10, at least, respond to the first command because of the time lag I noticed that corresponds to the Monterey's indication of a "bad first command." But the above statement seems to imply that TW523 devices read only the second command and act only if it matches the first.

Of course, the only place I have any TW523's are with the Omni and the CPU-XA so I probably wouldn't notice any time lags in their operation. Gawd, this stuff gets confusing.

Do you think the course at:

would help an electronic feeb like me to build something useful?

It's surely not current (This page last updated "The TW523 outputs a square wave, in sync with the power line frequency and within the 50 microsecond window of zero crossing. This is a 60 Hz square wave."

Does this mean that the TW523 essentially "follows" the powerline and that by looking at one of the data lines coming from the unit you will see a logical 1 for half of one powercyle and a logical 0 for the other half? Does the "within the 50µS window of zero crossing" imply that it takes up to

50µS to process the zero crossing information and place it on the TW523's output line? Which I can't claim to undestand at all. )-:

OK, I've got to read up some more . . .

-- Bobby G.

The TW523 is not a good choice for a diagnostic tool unless you modify it as Neil Cherry has done. Even then it is not a good choice to measure signal amplitude.

The TW523 actually outputs on a delayed basis. It reports the first copy of the X-10 code during the time frame of the second copy. This means it's too late to see a collision in time to do anything to avoid it. It also only reports part of the actual powerline activity so, for example, it does not report all dim/brights or extended codes.

It also outputs an opto-isolated square wave that is in sync with the 60Hz line frequency. It's purpose is to provide a sync signal for external devices to input X-10 pulses at the proper times.

Maxim bought Dallas a few years back. I don't know whether the DS5000 is still made.

I would suggest an easier way to learn about microcontrollers. The BasicX-24 uses an Atmel µController plus an external EEPROM and inverter (for RS232) and is programmed in Basic (same dialect as BasicStamp). While its slower than a directly programmed µController it is fast enough and powerful enough to handle most HA related tasks. It's a cheap way to learn, as the programming language is a free download, although its probably easier for a beginner to buy the development system.

If you later want to take a more low level approach, there are Basic language compilers for both Atmel and PIC µControllers that allow you to mix assembler statements where you need even faster execution. The µControllers are getting more powerful - faster with more RAM and internal EEPROM. They are dirt cheap.

There are also many books and tutorials >> amplitude (8-bit resolution) at ZC+250µS & ZC+900µS as well as the number >of

µControllers

That sounds like a better deal. I'll look around.

Thanks for the pointers. In reading up on the HK site I saw a lot of things that reminded me of C-Max and the CPU-XA which I guess shouldn't surprise me much. I'll start reading up.

-- Bobby G.

I think it made the conversion - they even offer a version with a real time clock. But the kit's $160 so it's probably going to be cheaper to go with the BasicX-24.

-- Bobby G.

As I noted, the TW523 is not a good choice but your question reminded me of another you asked about using an appliance module as a diagnostic platform and it dawned on me that you might have seen some reference to Phil Plunkett's design for an X-10 compatible appliance module.

With modifications to use it with 120V, eliminate the tuned inverters and a different PIC (and firmware), that would make a good diagnostic platform.

But it's probably simpler to start from scratch.

I've decided it's simpler to live with the Monterey's limitations and keep reading up on . I'm falling so far behind on my project list that I may never see daylight. Worse, still, I am committed to going to an "open house" this weekend to look at outrageously priced real estate. Want to know when the real estate bubble will burst? Right after I buy a home that I can barely afford!

The Stamp unit looks like it might be ideal to create a home "sensor web" of audio, video and other inputs that's capable of talking to Dallas 1 wire components as well as X-10.

-- Bobby G.

In which case you really want all of your X-10 stuff to be working. ;)

You'll get more bang from the BX-24. It can send X-10 (using a PL513 or TW523). Neither it nor the Stamps work very well for receiving X-10 PLC.