DW1 Door Sensor: How to Use Second Key for Reed Switch Closed State Notification?

Hi all,

I bought a DW1 Door Sensor and it is working perfectly, but I need to know the effort to make a modification to this sensor.

Basically the Sensor has a Reed Switch, a EV1527 encoder and an R433A Transmitter and has 4 pre-configured keys and only 1 is used. These keys are preconfigured numbers that are activated by Jump. (Ex key1 = 123, key2 = 321, if I want to change the key when the door is open just change the jump from key1 to key2, then instead of receiving 123 on the receiver I will receive 321).

Challenge:

I have no idea where to start, I'm IT guy.
I need to know when the door was closed (reed switch closed). 

My idea is to try to use a second keys to send data when the Reed Switch changes from Open to Closed, and it currently only sends data from Closed to Open.

I do not want to change the keys just change the board circuit to use the second key for that purpose.

I am attached the pic of the board. 
If you can help me, I'll be grateful.

Levi, I daresay this might be possible, but you'd need a bit of prodding around with a multimeter to do it.If you look at your jumpers, one side appears to be common and the other has four tracks. one leading from each of the 4 jumpers.You'd need to find out what is happening with the active jumper when the door opens.  Does it go from low to high or from high to low?  Is it a constant change or do you get a pulse?  Using the multimeter, find out if the jumper point is directly connected to the reed switch ?  if not, where does the reed switch connect to?I daresay it would be possible to make this work the other way around, by using a CMOS inverter (you have a nice 12V supply and CMOS consumes almost nothing when not changing state.  It may be as simple as connecting a cmos inverter from the active jumper to one of the other jumper points, or it may be more complicated than that.  These devices are optimised for low power consumption and there are all sorts of tricks they use to get that.The other option is to get a different reed switch.  I know you can get changeover reed switches, if you put one of those in it could work in the opposite sense.  Your device would then only sense door closings, not door openings, I read that you want to sense both?From your description it sounds like you have a basic knowledge of electronics but if the above does not make much sense, find a friend who can make sense of it.

The EV1527 is a pretty simple chip. The thing that's NOT apparent is how it gets triggered to send out a code. My guess is that when the  reed switch closes, there is a pulse that is generated to trigger the output.It would require a bit of work to trace out the circuit to figure this out.Another way to go about this is to get a second door sensor and a reed switch that opens instead of closes. Then set the code on the second one to key 2 and use it to detect when the door closes.

The circuit for these units is derived from this:

https://oshwlab.com/drinker66ru/ev1527-dw1

As you'll see the reed switch pulses a FET to power the chip for 2 seconds. It's a very simple design and a A23 12V battery lasts years

In short:

Yes, you can do it by adding more components. There's at least one Youtube video on retrofitting them to do it

No, it's not worth it. The parts cost of doing so is higher than just buying better sensors in the first place, let alone the time factor and differing Vcc requirements

DW1s are useful pulse sources, but that's about it