TP-Link’s Tapo P125: A smart plug with an Apple HomeKit vibe

Does the addition of Apple smart home protocol support necessitate hardware augmentation and upgrade, or do firmware-delivered feature updates suffice?

After pausing my TP-Link smart plug teardown publication cadence in May, I temporarily paused again in July (although the company’s products weren’t completely overlooked last month, mind you). It’s August, and I’m back on the treadmill, this time with a look at the Tapo P125, which adds Apple HomeKit support to the Tapo P105 foundation I dissected at the beginning of June.

I’d bought a Tapo P125 two-pack from Amazon’s Resale website area last November during a 30%-off holiday promo sale, for $12.59. Here’s a stock shot of the Tapo P105 four-pack acquired at the same time, for comparison’s sake.

The two products are dimensionally identical (2.4 × 1.5 × 1.3 in, 60 × 38 × 33 mm) and more broadly visually similar, save for the Tapo P105’s front panel status LED, whose illumination-related information has been relocated to the side-located switch on the Tapo P125 (non-illuminated in the Tapo P105 predecessor).

A history revisit

As a reminder, as it’s been a while since I started this particular teardown-coverage sequence, my basic aspiration with this project is to ascertain to what degree (if any) differences in the company’s various smart plug products’ feature sets, broadly between the Kasa and Tapo product lines as well as between products within a given line, are due to hardware variability versus (or in addition to) software-implemented inconsistency.

Here’s the so-far published dissection list:

Note that hardware changes can, of course, be developer-motivated not only by evolving feature set requirements but also by the phaseout and replacement of building block components inside these devices. Such supply chain impermanence also helps explain the multiple to-date hardware versions of each product as documented on TP-Link’s support site.

In the Kasa past, I made a two-notable-feature teardown jump from the EP10 to the EP25: not only added energy monitoring capabilities but also support for Apple HomeKit (and Siri, for that matter). In the more recent and ongoing Tapo era, the product feature iterations are more modest. As already noted, today’s Tapo P125 augments the baseline Tapo P105 with Apple HomeKit cognizance, while the Tapo P115 (dissection to come next month) instead adds energy monitoring capabilities.

And I’ll close out, hopefully before year end, with a teardown of the Tapo P110M: slightly wider albeit no taller (or shorter) or deeper (or shallower) than the Tapo 115 and also with energy monitoring support, but additionally offering Matter smart home ecosystem cognizance.

Enough of the background; let’s get to Tapo P125 tearing down. I’ll start with the remainder of the Amazon-hosted stock images, which for some unknown reason tend to be higher-resolution and otherwise higher quality than those on TP-Link’s own company and Tapo product sites.

This last one, always a pre-dissection favorite and in this case solely published on TP-Link’s own site, is the “conceptual teardown”.

Assuming it’s correct, it suggests a relocation of the mini-PCB containing digital circuitry from the upper corner of the device (seen below with the Tapo P105) back to the more common side locale.

As well as the re-integration of the LED onto that mini-PCB versus standalone and soldered to the main board in the Tapo P105 situation.

Prepping the patient

Let’s definitively confirm-or-deny the conceptual tease. Here are some box shots to start, as usual accompanied by a 0.75′′ (19.1 mm) diameter U.S. penny for size comparison purposes.

Per the obscured-but-still-faintly-visible box-bottom marking, the devices inside are based on v1.26 hardware (the initial release, per TP-Link’s support page, along with v1.6 and v1.8 successor versions). And what’s obscuring it is the as-usual additional sticker suggestive of, per its formerly-Warehouse origins, an initial customer return followed by an Amazon resale to me.

Often, albeit not always, such products were opened by their previous owners prior to being sent back (for various reasons, including malicious ones) for refund. So too was seemingly the case here, although the top of the box was still sealed (albeit damaged). When I instead initially opened it from the bottom, the cardboard around the then-left (normally right when upright) device’s plug was comparatively sullied versus that of its packaged companion.

Turning the box back over, cutting the clear plastic seal, and opening it revealed more evidence of the right-side device’s prior-owner disturbance.

So, I went with that one for the dissection.

Cute, huh?

Scrubbed for surgery

Here’s our patient.

The bottom side perspective was as-usual the most informative from FCC ID (2AXJ4P125) and other info perspectives.

The (not-)final cut

Potentially obscure reference

Time to dive inside, starting with the previously seen backside screw.

I’ve now done a few of these similar-form-factor dissections, and they seemingly get easier (for my body, if for no other reason) each time, since the first time.

This one was no exception to the trend…and yes, I realize I’ve just jinxed myself for future project(s) by typing those words.

Here comes the series of shots I know you’re all most interested in.

That blue-colored (this time) relay on the right, a common component (for…y’know…power switching reasons…) in all smart plugs I’ve taken apart to date as well as presumably also in the future, is this time a Churod A16-V-105DA2F, which we also found inside the Tapo P105.

Now for the smarts-packed mini-PCB on the left side.

Remove the foam square, zoom in, and:

That’s (once again) Realtek’s RTL8720, also previously found inside the Tapo P105, as well as in the Kasa EP25. Which might lead you to decide that although the mini-PCB and LED have been relocated (note the switch in the lower left corner this time, with the LED just to its right), the digital hardware is exactly the same as the Tapo P105. And which in fact seems to be a reasonable deduction, it turns out, although I’d initially thought otherwise.

The nexus of my initial confusion (putting aside my ever-present confusion about most if not all things) are the ICs you can’t see (clearly, at least) in my shots, on the mini-PCB backside, which was previously bare in the Tapo P105 case. Head back over to the FCC site, click on the Internal photograph link, and you’ll be able to see them for yourself.

The larger eight-lead chip, for example, is the exact same Eon Silicon Solution EN25Q32B 32 Mbit serial flash memory (marked QH32b-104HIP) as before. And the other, smaller, five-lead (two on one side, three on the other) SOT-packaged IC, marked FE1RYE and not noted (albeit still there) before, is function-unknown to me. On the Tapo P105, it (assuming my commonality assumption is correct) was marked ACeN2. Ideas, readers?

In closing, I as usual was unable to gain access to the PCB backside, although as you might be able to discern from these shots, there’s not much there to write home about, anyway.

If you really care, the FCC site is always there to alternatively satiate your solder-blob appetites. With that, I’ll wrap up for today. Reader thoughts are as-always welcome in the comments!

—Brian Dipert is the associate editor, as well as a contributing editor, at EDN.

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