Ultrasonic fireplace control - PING?

GICU812

I have a fireplace that is controlled with a remote. It operates on some sort of sound, I believe its ultrasonic.

I bought a PING sensor because I thought I would be able to use it to decypher and then replay the signal.

What im getting, when I run the standard PING program, if I press the ONor OFF·button on the remote, the PING distance responds as 1inch.

However, if I·turn off the pulsout·command, I·get nothing, if I debug the pin, I get nothing.

Also, I tried sweeping pulsout from 0 to 16000, and the fireplace didnt respond.

So, it didnt fall right into my hands, there are a couple of more things Im going to check, but I wanted to see if anyone had allready done this and had pointers.

There are no obvious markings on the fireplace, and nothing on the remote that would be relevnat.



·

SRLM

My suggestion would be to open up the remote, then use a oscilloscope to figure what signals are being sent where. It's certainly going to be easier than trying to use the Ping, as that device was not designed with even the remote possibility of remote control. (pun intendend [noparse]:)[/noparse]

Chris Savage

All the PING))) does is measure the time it takes to send out and receive a 40kHz burst. This starts at the time the unit is triggered until the sound is detected. If you’re firing at secondary 40kHz burst at it you can expect erratic values at best. You won’t be able to do what you’re trying to do. It just doesn’t work that way.

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Chris Savage
Parallax Engineering

GICU812

Ahh poo.. Well at least I get a new toy.

Here are the scopes off the back of the transmitter in the remote.

Looks like 39.3 khz turns it off, and 40khz turns it on. Seems that the ping shoud turn it on then.

When I hold the button, covering the transmitter, then uncover the transmitter while holding the button, it still works, and while holding the button I get a solid freq so there is no real signaling, just signal or no.

I'll have to scope the ping to see why it doesnt turn on the fireplace, might not be a long enough pulse. I suppose I could tap the transmitter leds on the PING and use the transmitter. Id pull the transmitter out of it, but I imagine I can get a US transmitter much cheaper than I could a new PING, for now I just want to see if it would work.



Post Edited (GICU812) : 10/24/2008 6:15:25 PM GMT

GICU812

I wonder if I could just use a Piezo and a pulsout command? The thing is pretty indiscriminate, I was working on something in the fireplace last year and I moved something, and I heard "CLICK HIIisssss... KERwumph!" just in time to jump out of the way. Whatever noise I made tricked it into thinking it was the remotes on signal. I couldnt get any readings off the PING, probably because the pulses are so short.

SRLM

Depends which Basic stamp you are using. The BS2 has a freqout range of up to 32 kHz. The BS2px has a range up to 197 kHz. So, any BS2 except for the original or BS2e should work.

GICU812

BS2p, I know I can generate in that range, Ive played with IR at 38khz, I just didnt know if a Piezo will generate the sound at that frequency.

SRLM

It probably will work. I guessing that the Ping))) uses a couple of piezo elements...

GICU812

It doesnt seem to have worked. I got pretty close and played several sweeps

for x = 10000 to 15000
freqout 15 , 100 , x
next

x * 3.77 = freq (BS2p)
I narrowed it down closer to 10000 to 11000 and ran increments of 10, didnt hit anything.

So I dont know.

I can get US transmitters here http://www.allspectrum.com/store/product_info.php?products_id=1300 for $6, just dont have the patientce

SRLM

Try

FREQOUT 15, 100, 10610



this is to get 40KHz on the BS2p. If that doesn't work, then hook it up to your oscillocope and see what differences there are. Unlikely, but possible. If all that works, then you know that you piezo doesn't work at that high frequency.

GICU812

Its probably the Piezo, on top of sweeping I tried the math based values.

My Parallax USB O-scope doesnt seem to be that accurate at higher freqs it jumps from 39.3 to 39.6 to 40 to 40.3

I might try just tapping into the back of the ping transmitter, I just dont know if powering the transmitter will backfeed and hurt the module, or I could desoilder a transciver and put it back later.

SRLM

I say just buy the $6 module. Isn't it worth it, rather than potentially ruining a $25 Ping)))?

GICU812

Yea thats probably what I should do.

I pulled the reciever out of the fireplace, it would appear all it does is short 2 wires together when on. So I could hardwire it, but Id rather have a remote module.

SRLM

Why not build your own reciever? If you use infrared, then you could use your TV remote and an unused button to set it off. Much easier than having a seperate remote.

GICU812

I thought about that. I want the stamp to be able to turn on the fireplace, part of the thermostat control im working on, and also to be voice controlled [noparse];)[/noparse] Ive allready got a remote for the fireplace, so it wouldnt make much sense to rework for another one, though it would be simpler to interface the stamp with IR

Doesnt much matter to me how the stamp talks to it, but it would probably be a pain to get wires into it. And it seems it would be easier to just shoot out a freq from the stamp into a US transmitter, rather than build a complex reciever circuit.