Computherm Q7 RF - 868 Mhz

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kofi
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Posts: 1
Joined: 08 Jan 2018, 16:13

Computherm Q7 RF - 868 Mhz

#1 Post by kofi » 09 Jan 2018, 14:37

Hi,
I have Aurel Transceiver (868,3 Mhz). My goal is to control heating with RF Link.

At home I have this wireless Thermostat operating at 868 Mhz:

https://www.amazon.co.uk/COMPUTHERM-Q7R ... B00SI1D6FY

ON Signal:
2018-01-06 21:50:53 - 20;04;DEBUG;Pulses=466;Pulses(uSec)=120,6420,510,510,540,330,90,300,90,330,90,300,120,120,300,120,300,120,300,300,120,300,90,330,90,300,90,120,300,120,300,90,300,120,300,120,300,300,90,120,300,120,300,120,300,300,90,300,90,300,90,300,90,300,90,300,90,300,90,300,120,300,90,300,90,300,90,300,90,120,300,120,300,120,300,300,120,300,90,300,90,300,90,120,300,120,300,120,300,90,300,120,300,300,120,120,300,120,300,90,300,330,90,330,90,300,90,300,90,300,90,300,90,300,90,300,120,600,510,480,570,300,90,300,90,300,90,300,90,120,300,120,300,120,300,300,120,330,90,300,90,300,90,120,300,120,300,120,300,90,300,120,300,300,120,120,300,120,300,90,300,330,90,300,90,300,90,300,90,300,90,330,90,300,90,300,120,300,90,300,90,300,90,300,90,120,300,120,300,120,300,300,120,300,90,300,90,300,120,120,300,120,300,90,300,120,300,120,300,300,120,120,300,90,300,120,300,300,90,300,90,300,90,300,90,300,90,300,90,300,90,330,90,600,510,510,540,300,90,300,90,300,90,300,120,120,300,120,300,90,300,300,120,300,90,330,90,300,90,120,300,120,300,90,300,120,300,120,300,300,90,120,300,90,300,120,300,300,90,300,90,300,90,300,90,300,90,300,90,300,90,330,120,300,90,300,90,300,90,300,90,120,300,120,300,120,300,300,120,300,90,300,90,300,90,120,300,90,300,120,300,120,300,120,300,300,120,90,300,120,300,120,300,300,90,300,90,300,90,300,90,300,90,300,90,300,90,300,120,570,540,510,540,300,90,300,90,300,90,300,90,120,300,120,300,120,300,300,120,300,90,300,90,300,120,120,300,90,300,120,300,120,300,120,300,300,120,90,300,120,300,120,300,300,90,300,90,300,90,300,90,300,90,300,90,330,90,300,120,300,90,300,90,300,90,300,120,120,300,120,300,90,300,300,90,300,90,300,90,300,120,90,300,120,300,120,300,120,300,120,300,300,120,120,300,90,300,120,300,330,90,300,90,300,90,300,90,300,90,330,90,300,90,300,120,6990;

My understanding is that these are 4 signals with preamble - 4times 500+ Pulse

When analyzing signal using Manchester encoding, where 300= HIGH, 90/120 = LOW:
Transition from high to low = 1, from low to high = 0:
330,90=1,300,90=1,330,90=1,300,120=1,120,300=0,120,300=0,120,300=0,300,120=1, etc.. I get to:

11110001 11100000 10001111 11111111 00011110 00001000 11111111
___F1___ ___E0___ ___8F___ ___FF___ ___1E___ ____8___ ___FF___

When debbuging I see that byte 3 is On (8F) and OFF (80h).. I guess the byte1 would be device ID and Byte 7 perhaps checksum??

Can someone help with codding plugging to RF Link?

I wrote email to frankzirrone yesterday, so perhaps he will have a look - but anyway I wanted to share these steps for others in case you'd want to troubleshoot and decompose RF signals yourself.

Martin

speeduhh
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Posts: 1
Joined: 14 Jan 2019, 11:08

Re: Computherm Q7 RF - 868 Mhz

#2 Post by speeduhh » 14 Jan 2019, 11:14

Hi, I am also interested in decoding this thermostat controller in order to be able to send the commands from an arduino or raspberry device. My googling got me to the point of reading about FHT and FS20 protocols. https://translate.google.com/translate? ... 20protocol

denxhun
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Posts: 1
Joined: 07 Apr 2019, 10:45

Re: Computherm Q7 RF - 868 Mhz

#3 Post by denxhun » 07 Apr 2019, 10:52

Hi there,

Did you manage to step forward with this? I have 2 of this and keen to utilize them...
What transciver have yoe exactly used for sniffing? Do you know what encoding used for RF? ASK, FSK, other?

Maybe I can help the implementation of the protocol...

BR,
Denes

darkbyte
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Posts: 1
Joined: 05 Nov 2019, 22:12

Re: Computherm Q7 RF - 868 Mhz

#4 Post by darkbyte » 05 Nov 2019, 22:22

Hi,

I think this is exactly what I need. I have a Delta TC7E thermostat, which seems like a rebranding of the older Computherm Q7 RF model. Probably the old and new Q7 RF is using the same protocol, but it's just a guess. Based on the manual the devices work exactly the same.
It seems you have gone way ahead of me trying to decode the protocol. I've borrowed an RTLSDR capable tuner from a friend of mine, in hope of understanding it, but it was more than I could chew. :( Maybe this time with this information at hand I can try it again.
Is this something we can replicate with a 868MHz transmitter easily? Any idea how the pairing between the thermostat and the receiver work? Is the receiver simply repeats a signal on different frequencies and receiver "locks onto" it?

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