Any Idea on How to record raw data ?

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Hello

 

there is a receiver that produces data over a single pin (0 and 1) at uknown format at 1250herz at TTL levels

 

is there any idea on how to record these data to decode its stream ?

Last Edited: Tue. May 30, 2017 - 06:10 PM
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Continuous stream, or burst? If the latter, how long? Any known special pattern that starts the stream?

 

Can you say anything about the device producing the bitstream?

 

Seems like a perfect job for a logic analyzer, e.g. like the Salae.

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receiver = MICRF211

actually there is burst

 

uknown how long but short enough, it react to commands and then stop, but i am sure it is receiving too much garbage

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plouf wrote:
short enough

Care to expand? Short enough for what?

 

So, its a 433 MHz receiver. Is this for receiving the ubiquitous remote mains switches or thermometer or... If so, last time I looked there was loads of projects online, some good and some bad. Perhaps there is one using a MICRF211 receiver.

 

Heres an example of a reverse engineering discussion (just the first one I hit when searching, nothing special, just an example): https://electronics.stackexchang...

 

No logic analyzer, then? When I played with a both a remote switch transmitter and a radio-thermometer I had some success looking at it with my Salae. (I shelved the project when it turned out my receiver was a bad cheapo thing, and other things came in between before I was done surveying what receiver to really get..)

 

EDIT: Googling "decoding 433 MHz" will give you loads to read and investigate.

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Last Edited: Tue. May 30, 2017 - 06:38 PM
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plouf wrote:
MICRF211

 

RTFM: MICRF211. 3V, QwikRadio. ®. 433.92 MHz Receiver - datasheet: http://ww1.microchip.com/downloa...

 

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Yes awneil, but that says nothing about the protocol e.g. a remote thermometer uses.

 

Here's one example of people discussing the decoding of such a signal: http://forum.arduino.cc/index.ph...

 

There's sooo many people wanting to do such things (e.g. since many of the receivers are total crap UI-wise, or they want to run all their 433 MHz devices from one central remote rather than having one for the garage door, three for mains switches in different rooms, one for receiving thermometers/wheather-stations/whatever, etc etc). So if plouf could reveal what device is sending the data then it just might be that someone have already done the reverse engineering.

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JohanEkdahl wrote:
Yes awneil, but that says nothing about the protocol

Indeed.

 

It just goes to show that the receiver is (almost certainly) the wrong thing to be looking at. 

 

if plouf could reveal what device is sending the data

Yes - that is the important bit!

 

 

 

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Having done a bit of 433MHz reverse engineering - unless you know what sequence to look for, it is hard to decode unknown data from the noise. I haven't seen a project that does a record/playback - for infrared- yes, 433- no. Everything I've seen so far decodes specific protocols.

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correct protocol is unknown

 

i know part of the transmition , the serial of the transmiter. 

Just need to record data down !

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Then you essentially need to build a logic analyzer. You sample at a multiple of the bit frequency and do a "majority vote" on that. Eg 5 times the bit frequency. You could possibly do that on the fly, and then you only need about as much memory as you have bits in the transmission.

You really don't want to tell what's transmitting?

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i know part of the transmition , the serial of the transmitter.

So put a small resistor in series with the battery and measure the voltage (or current) pulses as it transmits.

Then you can hopefully decode the transmitter.

 

Then tackle the receiver.

 

JC  

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If you just want to record the data for examination - saleae logic is the #1 choice or use you PC's soundcard. Google soundcard oscilloscope.

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Are you trying to clone an existing transmitter?

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Nah, he wants to annoy his neighbour!

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Can you tell if it is Manchester? Or NRZ? Or straight (framed) async data?

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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I've not seen a commercial device that uses uart framed data on 433MHz.
Manchester -yes
Fat pulse/skinny pulse - yes