Hi all

I am a complete noob, so please bear with me. I found this forum searching for an IKEA sensor hack, so seems like a good place to ask. Also, I hope everyone is keeping well in this climate.

I have an older E1525 IKEA Tradfri motion sensor. The one with the dial on the back for timeout. The minimum setting available on this unit is 60 seconds, as can be set from the dial on the back that shows 1, 5, 10 (minutes). The problem is, that I find 60 seconds is not very useful when hooked up to something like Home Assistant as the sensor will show as 'Detected' for 60 seconds after motion has stopped. I get that the design makes sense when using Touchlink, but I don't.

I was reading here: https://community.smartthings.com/t/making-xiaomi-motion-sensor-a-super-motion-sensor/139806 that the Xiaomi Aqara sensor also has a minimum 60 second timeout, but was modified to be ~5 seconds. So I found myself here I would very much be grateful for some input on if this could be achieved with this sensor too.

It appears that the dial is just a plain potentiometer marked B104. My first thought (and what I really hoped) was that the minimum resistance would not be zero, and just shorting the connections with a blob of solder might do the trick, but it looks like when it is in the '1' position, the potentiometer resistance is zero.

I could be wrong about these components but: The potentiometer seems to feed into a transistor on the other side that is marked 7002, and there is also a resistor marked '623' (or 823).

I found some photos of the PCB on twitter, as well as a couple of photos I have taken: https://imgur.com/a/UnqDxWl

So the question is: Is it possible to bypass this 60 second time out - or lower it to about 5 seconds? I am totally out of my depth here but would very much welcome any input as I enjoy the learning experience Thank you in advance for any and all help!

Ok, no worries. I'd like to thank you for spending your time on this

Ok, no worries. I'd like to thank you for spending your time on this

According to the pics I found, the MCU is a Silicon Labs Mighty Gecko EFR32MG1P132GI.

With 1 probe to ground I tested:

Pos leg with dial at 1 minute (min): 2.97V
Pos leg with dial at 15 mins (max): 2.97V
Neg leg with dial at 1 minute (min): 2.96V
Neg leg with dial at 15 mins (max): 2.95V
Variable leg with dial at 1 minute (min): 2.96V
Variable leg with dial at 15 mins (max): 2.97V

Seems like a very small change.. is this enough of a change to be useful?

My meter doesn't beep, but I get a reading of 0.1 between TP5_2 and the second pin from the right, this seems to be the lowest reading by far: https://imgur.com/a/RLFyOBP is this a sign that it is connected here?

But, when I set the potmeter to minimum the Voltage = 2.95, and this doesn't change... the potmeter set to max is still 2.95V...

Yeah sorry about that. My inexperience is probably exacerbating things thank you for putting up with me

I am looking at the potmeter, and I think I can fairly say the legs are like this: https://imgur.com/a/1bTBnUo

So with one probe on the variable leg, where to I test with the other probe?

It looks like the variable leg first goes to TP5_1, then to TP5_2, then to the MCU, but it is not clear which pin: https://imgur.com/a/hbgOOBU

Voltages:

All 3 potmeter legs to MCU (blue): 2.9V - Does not change when potmeter moved
All 3 potmeter legs to MCU (red): ~0.2mV-0.3mV - Does not change when potmeter moved

Resistance:

Top green on potmeter to MCU (red): 67K (turning dial does not change)
Bottom green dot on potmeter to MCU (red): 67K at max time, 110K at minimum time
Unmarked leg to MCU (red): 110K and does not change when potmeter moved

I think I may have screwed up one of the earlier measurements. I am using a better meter now, and I got this: https://imgur.com/a/AQk22sR

The Blue pin, which I originally said was connected to the VDD pin appears to actually be connected to the ground shield over the chip - I got a reading of zero. The Red pin, I got a reading of 3V (there abouts) and this is the one connected to the VDD pin on the E93196. Turning the potentiometer did not change the voltage on this.

I remeasured the resistance from the ground leg of the potmeter to top green dot is 77K, bottom green dot is zero when at 1 minute, both are at 77K when at 15 minutes

Sure, just to confirm though (because I've not measured anything like this before), I put one probe on the MCU pin and the other to ground? Ie. Battery negative? Sorry if this seems like a really dumb question

Ok, this could be a no go.

Looks like I can get some continuity between these points: https://imgur.com/a/PKPOJdk

So that would be connecting connecting VDD to ground?

But, with a DMM set to 200k, I get a resistance reading of 66.7 between these points: https://imgur.com/a/4K0NPbP because of R12....

Could this be the resistance that is putting that to 60 seconds? Could I connect those 2 green points? Or remove that Resistor and bridge with solder?

Gotcha. So we know that pin 4 on the E93196 is VDD, so if I get continuity from pin 4 on the E93196 to either the potentiometer leg or the MCU pin that I am going to be connecting it to, then it's a no go?

I can try - is there a possibility that I could fry it doing that?