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Author Topic: RF protocol (button up/down)  (Read 11575 times)

dhouston

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Re: RF protocol (button up/down)
« Reply #15 on: February 03, 2015, 12:30:56 PM »

In reality, the duplicate PLC instance was either the CM15A or HG not waiting long enough and issuing a second command.
I would posit that one or both are reacting to the first code received and relaying that via PLC. They are then deaf to RF for the time it takes for PLC but probably hear the last (i.e. 6th) RF copy and relay it via PLC. However, if one or both are polite transceivers, one may be backing off and then transmitting PLC once the powerline is free. It's complicated.
The software may be questionable, but the hardware (within limits) is very good.
Agreed. It's a shame they didn't publish the CM15A/CM19A communication protocols as they had with the CM11A. There are many developers who could have provided better software had they done so.

Finally, if you quickly hit/release a key a la a chicken pecking, you will probably see only five copies.
« Last Edit: February 03, 2015, 12:49:47 PM by dhouston »
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dhouston

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Re: RF protocol (button up/down)
« Reply #16 on: February 03, 2015, 12:38:45 PM »

...I wanted to use my SDR to capture RF primarily to determine relative signal strengths.
I cannot help with the SDR but there's a much simpler way to reach your goal. Look at http://www.cdadapter.com/srtune.htm. I think the technique used was based on one of my web articles but this page is easier to grasp/follow than my explanation at http://davehouston.org/tuning.htm. Using the meter after tuning a super-regenerative receiver for maximum will then let you compare signals from multiple sources (one at a time).

While this will not give you absolute values, it will give you a reliable (and repeatable) comparison of relative signal strengths. I've used it for my comparisons of various receiving antennas as well as for before/after X10 RF Feng Shui measurements http://davehouston.org/X10_feng_shui.htm.
« Last Edit: February 03, 2015, 12:48:06 PM by dhouston »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #17 on: February 03, 2015, 12:43:00 PM »

I'll check the link out.  I think I have things sorted out now that I added full wavelength passive antennas.  I still want to do the test out of curiosity, but it's not as critical since things work even in the rain.

toasterking

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Re: RF protocol (button up/down)
« Reply #18 on: February 03, 2015, 02:47:37 PM »

There is ABSOLUTELY NO WAY to determine when the key is released. There is NOTHING within the RF data transmitted by the remote to indicate this. So the SDK documentation is full of CRAP!

Just to satisfy my curiosity, I held down the second device ON key on an SS13A (as holding the first would have entered programming mode) and, still holding the key, yanked the battery.  The commands were received with a CM19A.  Sure enough, the last event from the SDK had -1 (the "button up" event) as the keydata parameter.  So there, I confirmed what you already knew:  The key up event is sent when there is a long enough gap between received RF events and doesn't confirm that the key was actually released at all.
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dhouston

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Re: RF protocol (button up/down)
« Reply #19 on: February 03, 2015, 03:01:46 PM »

I knew all of this because about 14 years ago, I designed a Home Automation device that interfaced with X10 and other devices. I designed a PCB, wrote firmware and Windows software. I had a couple hundred bare circuit boards made and gave them to my 12 year old grandson to sell for a few bucks each. Users had to add all the through-hole components. It included X10 RF and it logged RF codes as well as the RSSI (Received Signal Strength Indicator) for the RF signal. I provided support via a web page, user forum, comp.home.automation and email.

It was a bit ahead of its time as it used IFTTT long before IFTTT was a thing.

I published the source code and other people introduced similar devices although they ignored FCC rules and provided fully assembled devices.

My grandson sold about a hundred PCBs before he discovered girls, at which point he lost interest.

You can see the user manual at http://davehouston.org/manual.pdf. The numbers within brackets in the Output Window (p30) are the relative amplitudes of the received RF signals.
« Last Edit: February 04, 2015, 06:03:27 AM by dhouston »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #20 on: February 06, 2015, 01:16:14 PM »

Dave

I'm looking at your schematics for the RF receiver and it looks like you use 315MHz ASK receivers with 8 pins.  I'm looking to get a few 315MHz and 433MHz modules for now and future use (or just to sit in my box of parts  rofl).

Do you recommend that 8 pin version over the 4 or 6 pin variant?  It looks like the 8 pin version has 3 pins used for ground and 2 for power.  The 4 pin versions don't appear to have an antenna hookup.  Any opinions?  Maybe something I should specifically look for or look to avoid?  Just looking at the first link (RM1SG at RF Remotetech) I'm not even seeing the duel 4-pin version anymore.

dhouston

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Re: RF protocol (button up/down)
« Reply #21 on: February 06, 2015, 01:55:33 PM »

Most of the RF work I did was 12-15 years back and I bought a couple hundred of the 8-pin version from the manufacturer (Wenshing) for the BX24-AHT Transmogrifier. More recently, I've used and recommended the RM1SG.

The advantage of the 8-pin version is that one of the pins is at the data slicer input whereas you have to solder a lead onto the RM1SG. There are antenna solderpads on the RM1SG but no pins.

While some of the links are out of date, you can find low volume suppliers at http://davehouston.org/modules.htm.
« Last Edit: February 06, 2015, 02:02:00 PM by dhouston »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #22 on: February 06, 2015, 02:14:16 PM »

I went through each of those vendors and only a couple still seem to work and have the same modules.  Of those, there was only 1 or 2 that seemed to allow adding the item to the cart and it appeared shipping was prohibitively expensive for very small orders (~$22 for shipping).  I've located a few on ebay that look like a good fit, but so far all appear to be from overseas.

This is a 433MHz version:
http://www.ebay.com/itm/Super-heterodyne-ASK-OOK-RF-Wireless-Receiver-Module-433MHZ-112dBm-/181633631837?pt=LH_DefaultDomain_0&hash=item2a4a35465d

And a 315MHz version:
http://www.ebay.com/itm/2PCS-RF-wireless-super-heterodyne-3400M-receiver-module-OOK-ASK-315MHz-433-92MHz-/261559271902?pt=LH_DefaultDomain_0&hash=item3ce625c1de

The second link is confusing though as it is for 2 modules but they don't say if they both work for 315 and 433 or if it's one of each.

Sparkfun does sell the 315MHz version:
https://www.sparkfun.com/products/10533

And the 433MHz:
https://www.sparkfun.com/products/10532

...but they are both back ordered.  Should be restocked within a week or so, so I may just go that route.


Sourcing modules that are 4-6 pins is much easier as I said.  I may even be able to locate them domestically.

dhouston

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Re: RF protocol (button up/down)
« Reply #23 on: February 06, 2015, 03:44:00 PM »

You need to avoid superheterodyne - they are not tunable (in this type of low cost receiver) and usually have no RSSI output.

Sparkfun looks like your best option and theirs even labels the RSSI output which is what you want for tuning and measurement (with the peak detector circuit cited earlier).

In the past you could find the RM1SG on Ebay but I think you now have to email the supplier. Last I checked they had reasonable pricing/shipping and accepted Paypal. http://www.rfremotech.com/ReceiverModules.html There's a MailTo link at the bottom of the page.
« Last Edit: February 06, 2015, 07:05:20 PM by dhouston »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #24 on: February 06, 2015, 04:33:04 PM »

I'm not anywhere close to a novice with RF equipment.  I thought I was supposed to be looking for super-heterodyne when it should have been super-regenerative.  I appreciate the feedback.

Come to think of it, I think you actually sent me one or two RM1SG modules a couple years ago when I was working on improving my CM15A performance.  I know I didn't end up using it there (worse performance) so it should still be in my box of parts.  That won't help with 433MHz, but it gets me one module for playing with.
« Last Edit: February 06, 2015, 04:34:52 PM by bkenobi »
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dhouston

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bkenobi

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Re: RF protocol (button up/down)
« Reply #26 on: February 06, 2015, 09:19:56 PM »

I just checked my stock pile and found that I have 2 different types of receivers.  I have one module that I believe you provided (RX310SH-WB and MBXr10TX) that was used for testing on my CM15A.  I also have 4 modules with the part number CZS-3 and are marked with 315MHz (available in 433MHz too apparently).  They match this product:

http://www.yishi.net.cn/rf/ProductShow.asp?ID=195

Looks like these will be a good choice for 315MHz.  I'll find something similar for 433MHz.  I'm guessing these will match much of what's available on ebay and marked with Arduino friendly.  I think I got these from China so they were cheap but took a month to arrive.

dhouston

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Re: RF protocol (button up/down)
« Reply #27 on: February 07, 2015, 09:22:07 AM »

I just checked my stock pile and found that I have 2 different types of receivers.  I have one module that I believe you provided (RX310SH-WB and MBXr10TX) that was used for testing on my CM15A.  
No - the RX310SH-WB is my own design and the SH denotes it is a superheterodyne receiver. You cannot tune it nor is there an RSSI output. It's a wideband design which should work well with X10's LC controlled transmitters. http://davehouston.org/RX310SH-WB.htm
I also have 4 modules with the part number CZS-3 and are marked with 315MHz (available in 433MHz too apparently).  They match this product:
http://www.yishi.net.cn/rf/ProductShow.asp?ID=195
That is identical to the RM1SG. I've added some text to their picture - to show the antenna solder pads and show where to solder a lead for connecting to a peak detector circuit (see tuning/measurement link cited earlier).

The YiShi web page is informative. It states the bandwidth as +/-10MHz which is very wide indeed and butresses my argument that its bandwidth is why it works well with poorly tuned X10 transmitters. It also implies that you can tune it between 360MHz & 440MHz so you may not need to buy a 433MHz version.
« Last Edit: February 07, 2015, 10:49:27 AM by dhouston »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #28 on: February 07, 2015, 11:33:32 AM »

I saw that the documentation indicated a quite wide tuning band, but I'm not sure if I could get it tuned as needed.  Also, I don't have a 433mhz transmitter that I can continuously transmit with.  I found a similar receiver with a transmitter in 433mhz for under $5 shipped from the US, so I picked it up.  I figure with the transmitter, I should be able to tune any of my other 315MHz modules should I need more.

Btw, how long should a 433mhz 1/2 wave antenna be?

dhouston

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Re: RF protocol (button up/down)
« Reply #29 on: February 07, 2015, 12:15:05 PM »

At 433.92MHz, 1/2 wavelength is about 12-13 inches.
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