Sonoff DW1 433Mhz door/window sensor - Low battery warning capable?

Hi all,
I testing out a Sonoff DW1 433Mhz door sensor (AKA CD100S sensor) to HA via a reflashed Sonoff 433Mhz RF Bridge (ESPurna FW, works great). All works well, and very good range and I get reliable reporting from the door it’s fixed too. I used the RF Bridge’s WebGUI learning mode to trap and save the DW1’s code, all worked fine as stated above into HA via MQTT.
However, the small folded paper instructions that the DW1 comes with says in a round about way, that the unit sends a status message to the hub (RF Bridge in my case) every hour, and will also send a low battery warning when the battery is low (I’m guessing via a bit in the status message).
The switch has a common EV1527 code chip in it. The data sheets I’ve found all seem to be the same one page sheet from China, and contain nothing about that functionality…

Does anybody know if the EV1527 is actually capable of low battery warning ?
Martin

i guess we have wait to the battery is low and look at console on bridge Ip.
Any one knows if "Low High’ cam bu used to monitor the battery?
“RfReceived”:{“Sync”:12490,“Low”:420,“High”:1230,“Data”:“D44E4A”,“RfKey”:2}}

I believe that “Low” and “High” are measurements of the pulse widths of the signal, or similar.

I did some testing with some other 433MHz door/window sensors from Banggood to see what codes they transmitted. I don’t know if these would be applicable to others… These are “GS-WDS07” sensors from here: https://www.banggood.com/GS-WDS07-Wireless-Door-Magnetic-Strip-433MHz-for-Security-Alarm-Home-System-p-1174915.html at about $5.15 each. The sensors that I have are powered by a single AAA battery.

On the PCB, there’s provision for a “tamper” switch, but nothing is populated. If you short the pins, you can activate the “tamper” function and get a code transmitted.

Interesting that these things seem to have a programmer header, perhaps with pins labeled

G(round?) 
T(ransmit?)
R(eceive?)
V(cc?)

I wonder what to make of that :slight_smile:

So, for one of my sensors, I get these codes:

12F70A - open
12F70E - closed
12F707 - tamper
12F706 - low battery

The low battery code is emitted when the battery voltage is below a volt. I removed the battery, and connected my variable bench power supply, and slowly reduced the voltage. Going by the display on my power supply, I think about 0.8 V, but I’m not sure how accurate it is, and I didn’t bother to measure the actual voltage that it tripped at, mostly just looking to see if it did anything with a low power supply voltage.

Also of interest, this particular sensor seemed to have about a 28 microamp standby current. This I measured with 4.5 digit Fluke 8050A bench multimeter and should be pretty close. Of course, the current spikes up quite a bit when it decides to transmit… I didn’t bother to try to measure that.

I only got around to doing the low battery test on one of the sensors. The other 3 had these codes:

13D20A - open
13D20E - closed
13D20F - tamper (no switch actually installed) (the tamper code on this is different from the rest - maybe have to re-test?)

and

13DA0A - open
13DA0E - closed
13DA07 - tamper (no switch actually installed)

and

13FD0A - open
13FD0E - closed
13FD07 - tamper (no switch actually installed)

Sorry that I didn’t have an answer to your specific question. Maybe this could be helpful if these devices share some common transmitter chip?

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I also have these which are similar but with tamper switch soldered and they also send 4 codes as mentioned.

https://www.aliexpress.com/item/5pcs-433MHz-EV1527-two-way-wireless-intelligent-door-window-sensor-APP-control-wifi-door-detector-for/32642367411.html

As it seems 06 is common for low battery

19:28:28 MQT: tele/sonoffbr/RESULT = {“RfReceived”:{“Sync”:14080,“Low”:460,“High”:1370,“Data”:“BD3206”,“RfKey”:“None”}}

19:30:19 MQT: tele/sonoffbr/RESULT = {“RfReceived”:{“Sync”:14060,“Low”:480,“High”:1340,“Data”:“0B6006”,“RfKey”:“None”}}

20:22:11 MQT: tele/sonoffbr/RESULT = {“RfReceived”:{“Sync”:14100,“Low”:460,“High”:1370,“Data”:“B7EF06”,“RfKey”:“None”}}

20:26:04 MQT: tele/sonoffbr/RESULT = {“RfReceived”:{“Sync”:14060,“Low”:470,“High”:1350,“Data”:“0A2B06”,“RfKey”:“None”}}

20:31:05 MQT: tele/sonoffbr/RESULT = {“RfReceived”:{“Sync”:14110,“Low”:470,“High”:1360,“Data”:“BDA406”,“RfKey”:“None”}}

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