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Author Topic: RF protocol (button up/down)  (Read 11614 times)

bkenobi

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Re: RF protocol (button up/down)
« Reply #30 on: February 07, 2015, 12:21:18 PM »

I just looked at the module and found that my test leads are all too big to clip onto the SMD leg.  I'm thinking of heading down to the biggest only electronic store in the area to find some as well as the caps and resistors for the test circuit.

bkenobi

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Re: RF protocol (button up/down)
« Reply #31 on: February 08, 2015, 12:17:34 PM »

I just found an interesting program for SDR dongles.  It looks like I may be able to use my radio receiver on the Raspi to see 310MHz and 433MHz and decode on the fly.  I don't know that I can get signal strength yet, but it's something that seems possible.
https://github.com/merbanan/rtl_433

I'm thinking that if I can get the signal strength out, then I should be able to modify the code to work on 310MHz.  Would be interesting if I could receive both frequencies at the same time.  If so, I could use this radio to watch for various modules at the same time without installing dedicated receivers.  One step at a time though...

bkenobi

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Re: RF protocol (button up/down)
« Reply #32 on: February 13, 2015, 01:52:15 PM »

I just received the last package of find components that I think I need to do some of this range testing.  I have super-regenerative and super-heterodyne modules in 315MHz that can be tuned down to 310 with a screw.  I didn't want to solder to the spots on those receivers due to size and the components being surface mount and potentially wanting to tune multiple modules, so I purchased some pico sized grabbers from Sparkfun that grab the leg of the SOIC really nicely.  The transmitters will just be the X10 modules.  It looks like I'll be able to use my DC power supply to power the module and since I'm measuring the signal at the test point, I don't need to connect the data pin to anything, right?  I'm planning on tuning some 433MHz modules too, so this will be interesting.

dhouston

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Re: RF protocol (button up/down)
« Reply #33 on: February 13, 2015, 02:46:26 PM »

+5V, GND & the data slicer input (connected to the peak detector circuit referenced earlier) are all you need.

Do you have a link to the Sparkfun pico sized grabbers? They might come in handy.
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bkenobi

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Re: RF protocol (button up/down)
« Reply #34 on: February 13, 2015, 04:39:52 PM »

The grabbers aren't actually pico sized (not sure what that means really).  I bought some EZ-Hooks a while back that are pretty small and very nice for the price.  But, they don't work with small components (~0.1" minimum).  I bought them at Fry's and their web site is terrible to find anything on or else I'd link to them.  They are basically a 5 pack of grabber to grabber test leads and look similar to these:

http://www.vetco.net/catalog/product_info.php?products_id=11877

The ones I just ordered were much smaller and definitely can hook onto the legs of the SOIC on the receiver board.  But, the insulation is a little wide so I couldn't grab 2 legs next to each other.  For the price, they seem very good though.

https://www.sparkfun.com/products/9741

FWIW, I contacted Digikey and they indicated that either a P25 or XPM series would be great for grabbing SOIC but the price for the connector alone ($2.50-10.00ea + S&H) was prohibitive for my needs (very low need).  The Sparkfun hooks were ~$7 shipped for 5 and I ordered other stuff too.


EDIT:  Oh, and the other thing about the very small grabbers is that they can cost WAY more.  I was just looking at a set on Digikey that were really cool!  Then I saw that the kit of ~10 hooks cost $500.   B:(
« Last Edit: February 13, 2015, 05:02:42 PM by bkenobi »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #35 on: February 15, 2015, 11:53:26 PM »

This is a bit astray from X10, but it's related to this thread...sorta.   :'

I've got a question about the type of receiver I ordered.  I thought it was a super-heterodyne, but since it doesn't work and it doesn't match the description on the code page that I'm working with, I'm starting to think it's actually super-regenerative.  I don't really understand the difference, but the high level description indicates I may have the wrong type.

Quote
A superheterodyne board:

    is cheap
    has one decently-sized chip on board (the RX3400-LF is 24-pin SSOP), which may be covered in a metal shield
    has a crystal (typically 6.773 MHz for 433.92 MHz RX frequency)
    has no obvious coils or tuning chokes

A super-regenerative board:

    is very cheap
    typically only has one small chip (like an 8-pin LM358 op-amp)
    has no crystal
    has a coil and a tuning choke
    doesn't work for this application.

Looking at the board I got from Sparkfun, it really sounds like it might be super-regenerative based on the list above.

https://www.sparkfun.com/products/10532

I guess I assumed that all 8 pin boards were super-regenerative.  But, there is crystal and there is a tuning choke.  I can get a different one, but I need to know what I should be looking for.  Any help would be awesome!  Oh, for reference, this is the code I'm trying to work with:

https://github.com/scruss/Powermon433

dhouston

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Re: RF protocol (button up/down)
« Reply #36 on: February 16, 2015, 06:48:46 AM »

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dhouston

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Re: RF protocol (button up/down)
« Reply #37 on: February 16, 2015, 07:46:50 AM »

Looking at the board I got from Sparkfun, it really sounds like it might be super-regenerative based on the list above.

https://www.sparkfun.com/products/10532
Those are WenShing's super-regenerative receivers that I used 12+ years ago. I'm not sure what you are trying to do but I doubt these will tune to 310MHz whereas the Yishi CZS-3 (identical to RM1SG) are purported to be tunable over a very wide range.

For X10, you need something that will tune to 310MHz like the CZS-3 or RM1SG or the 315MHz version of the WenShing receiver from Sparkfun. https://www.sparkfun.com/products/10533
The advantage of these WenShing super-regeneratives is that the linear output (pin 3) is the data-slicer input that requires adding a lead with the CZS-3 or RM1SG.

I do not know exactly what you are doing with 433.92MHz but doubt you need a tunable receiver as most 433.92MHz devices are fairly stable so a non-tunable crystal controlled super-heterodyne receiver is preferred. Europe uses 433.92MHz for X10 and nearly everything else in this class. They have far more stringent regulations which necessitate crystal controlled super-heterodyne designs. And, while super-heterodyne can be made tunable it almost never is for these low cost fixed frequency applications.

This is not the place to delve into the details of super-regenerative vs. super-heterodyne. You can explore this via Wikipedia.  
http://en.wikipedia.org/wiki/Regenerative_circuit
http://en.wikipedia.org/wiki/Superheterodyne_receiver

For your power monitoring application, you will need a stable 433.92MHZ super-heterodyne receiver like...
https://www.sparkfun.com/products/retired/8950
http://www.canakit.com/rf-link-4800bps-receiver-434mhz-wrl-08950.html
« Last Edit: February 16, 2015, 07:50:36 AM by dhouston »
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bkenobi

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Re: RF protocol (button up/down)
« Reply #38 on: February 16, 2015, 10:51:47 AM »

Like I said, my goal here is X10 (310MHz receiver for understanding signals and their strength) as well as non-X10 automation (receiving 433MHz signals from a power monitor, weather station, other).  I asked the module question here primarily bescause you are the most knowledgeable person I know when it comes to RF.  Heck, I've seen your content linked all over the place!  I really appreciate you taking the time to give guidance even when it's not 100% related to this forum topic.

dhouston

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Re: RF protocol (button up/down)
« Reply #39 on: February 16, 2015, 01:09:43 PM »

To reiterate (aka  >*<)...

For X10 you MUST be able to tune to 310MHz and for measuring signal strength you need access to the data-slicer input. Both require a super-regenerative RF receiver. The easiest way is to use a receiver which has a linear (aka analog) output such as...
 https://www.sparkfun.com/products/10533
although you can attach a lead to the RM1SG/CZS-3 to accomplish the same thing.

For 433.92MHz, you  can use... 
 https://www.sparkfun.com/products/10532
if you want to measure signal strength or, again, can add a lead to the 433.92MHz versions of RM1SG/CZS-3. If you do not need to measure signal strength, a super-heterodyne receiver will generate less noise and be more stable, frequency wise.

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