The OLEBY sensor light’s hidden secret

Older, yellow OLEBY on stairs

I’m working on a simple little project (ESP01S-based) right now which needs to be able to sense a warm body nearby, so naturally I turned to my stock of IKEA OLEBY sensor lights (having hacked several in the past and having been impressed with their all round, mmm …cheapness). For such a bargain price, it was almost worth buying them just for the battery holder, but an ancient grey-beard like me really needed a couple for their intended purpose …to light the way to the toilet at 02:00. So I bought a small stock of them (not enough, as it turned out), ripped out all of the white LEDs and replaced them with a single, yellow one and added a CDS sensor on pin 9 of the BSS0001 chip to ensure that they only switch on at night. A couple of them have been sitting (out of kicking range) on the stairs for several years now and are worth their weight (without batteries) in gold.

Anyway, when the need came up for the warm-body-sensor, I immediately thought of the depleted stock of OLEBYs sitting in the drawer, still in their original packaging. As I mentioned above, I wanted the sensor to interface with an ESP01S, so that I could MQTT the heck out of any warm bodies that came into range in the middle of the night (I’m totally screwed if the intruder happens to be a zombie of course). The reason the OLEBY and ESP01S are such a good fit is that the sensor will be working in the middle of a field …and the bodies in question (zombies or not) may not always be human shaped. The field in question is outside of mains-extension-cable range, but is still fairly close to our house; close enough for an ESP to be able to piggy-back off our WiFi network. The idea is that the OLEBY will trigger as usual, but instead of turning on a bunch of LEDs, it’ll turn on the ESP8266 instead. The ESP will boot, latch the power switch on (as the OLEBY will time out if not re-triggered) and then quietly send an alert message to our MQTT server, which we can then act upon depending upon how close to harvest time it is (lights, noises, hand grenades, dynamite or 200W rendition of Slade’s “Merry Christmas” …no, you’re right, that last one is probably banned by the Geneva convention).

The bare (apart from all of the flux) OLEBY PCB

So, poking about in the (fairly manky) guts of a dismembered OLEBY (don’t they have any de-fluxing solution in the middle kingdom?) trying to find where the trace from pin-2 went before it hits the LED switching transistor/FET, I discovered something interesting. The brand-new batteries I’d just slotted into the thing measured a pretty reasonable 4.83 volts …but the output from pin-2 measured 5.1v. Eh?!?

In all of the times I’d had the backs off these things, I’d never really looked closely at anything very much beyond the BSS0001 chip or the LEDs, but it seemed like there was something quite interesting going on here. There’s no mention of a charge-pump in the BSS0001 datasheet, so what was happening?

The answer appears to be in that clump of components across at the left-hand side of the board, away from the sensitive BSS0001, where an electrolytic capacitor sits on the reverse (LED) side of the PCB. Something needs a little bit of smoothing (first clue). Now that I get the magnifier out, I can see that a three-pinned device which I’d assumed was a transistor driver for the LEDs is actually labelled as “U1” (second clue). And there, hidden in plain view right next to U1, are a fairly chunky diode and another component labelled as “L1”. Well, who’d have guessed it …the humble (and don’t forget cheap) OLEBY has a fixed-voltage, boost regulator inside it. No wonder the things never seem to lose any sensing range, no matter how dead the batteries get.

U1 is something of an enigma. There are no particularly legible markings (“E502”?) on the chip itself and, until today, I would have been willing to bet that there was no such beast as a three-pin boost regulator chip. To begin with, I was working on the assumption that it was probably a transistor being driven by a clock signal from the BSS0001. However, a Gewgull search first turned up the ON Semi NCP1402, five-pin, micropower regulator, where one pin is marked as “NC” (no connection …hah, maybe the “NCP” part of the NCP1402 stands for Non-Connected-Pins!) and yet another, the chip-enable pin, can be permanently tied to the output pin, so we have at least a theoretical three-pin boost regulator after all. A little more searching through supplier product listings produced a couple of entries for SOT23-3 devices, like the TI TPS613222. So there is such a thing as a three-pin, SMD, boost regulator chip after all. Not only that, but the link to the TI datasheet above will open at an example circuit which seems to be a perfect match for the OLEBY layout (although the actual pin assignments for the TPS613222 don’t match U1).

I’ve just checked the on-line IKEA catalogue for the OLEBY sensor light and, here in Japan anyway, they still have them in stock (although the colours seem to be limited to black, white and red …and the price seems to have gone up, too), but it may still be worthwhile picking up a few the next time you’re in your local store buying some kitchen cabinets, coz’ now you know you’ll be getting a handy-dandy, micropower regulator for your battery-driven projects as part of the deal (oh, and lots of extra flux, too).

If the non-zombie detector ever gets to the decent working prototype stage, I’ll publish another article with the details and link to it from this page (but don’t hold your breath).

Intel-based, 4-port firewall/router for less than $200

NOTE:-  This article was originally written mid 2019, but was never posted (it seems that I received a non-maskable interrupt in mid sentence and never got back to it).  Prices quoted are probably no longer valid, but I note that the systems themselves are still available from the supplier linked-to below.


As noted a couple of months back in the Odd Bargains post, I’ve been experimenting with some low-cost Celeron-based systems (in addition to the original Z8350, Atom-based unit, which started me along this particular track) as cheap, complete servers for our home network.  The main advantages for me are good OS support for most (but definitely not all) peripherals, RTC and battery as standard and they all come complete with a case and power-supply included in the up-front price.  They are a lot cheaper to run too, as these low-end processors were originally intended for laptops and tablets rather than full blown PCs.  Santa Claus only delivers for free at ChristmasWhile there’s no denying that the CPU performance is generally nothing to get too excited about, they (the quad-core units, especially) still work remarkably well as 24/7 infrastructure servers for services such as DNS, NTP, DHCP, low volume web servers and reverse proxies.  Most ,but not all,  come with a GbE port and are quite capable of handling significant amounts of traffic (…watch out  for the low-end “ACE PC” branded models though, as they only have a 100Mb port), but all GbE chipsets are not created equal and my tests with a cheap, external USB-3 to GbE dongle (as a super-budget firewall) were a resounding failure (the internal port on the Celeron box could handle the traffic, but the dongle would give up the ghost after 2 or 3 hours).

I found along the way that there are quite a few, virtually identical systems in this price range which have completely different chipsets.  Most of the very low cost machines come with Realtek chips, which research on the ‘net shows to be less than ideal for a firewall (the symptoms reported are similar to my own experience with the USB-3 dongle).  This isn’t to say that the Realtek chips are to blame (there are lots of other variables in the mix), but it is fairly common to see posts recommending Intel chipsets for long term reliability under heavy load.  So, after playing around with a couple of systems that I actually have and taking into account reviews and research, I eventually came down to the choice of a J3160 based system with four, Intel-based GbE ports (the J3160 because it’s a quad-core chip with slightly better performance than the Z8350 and (importantly) with AES-NI hardware cryptography support and four ports because I need to provide for a couple of “guest” networks, firewalled off from the main, home network).

I found a reputable looking supplier on Alibaba who had a lot of good feedback and decent prices (they sell under the names of “Yanling”, “Minisys” and “iWill”).  The model I chose was their Nuc-C3L4.  In addition to the four (Intel) GbE ports, it also comes with dual-HDMI, 2x USB-3.0 and an RS232 console port.  The cost for the bare-bones unit is was $142.60, but that doesn’t include shipping (which was an additional $20 for my location).  This vendor does accept PayPal, but only from a limited range of countries (and mine wasn’t one of them).  Depending upon where and how you’re shopping, you can probably get 4GB of memory and a 64GB eMMC card for an additional $30, or so.  And yes, because I have used this supplier and had a good experience with them and their products, I do recommend them.  Communications with them (in English) were easy, fast and friendly.  NUC-C3L4 unboxedTheir shipping was also fast and their packing is excellent (the boxes are sturdy and the units are completely surrounded by a custom, expanded polystyrene foam cushion …which may not be very environmentally friendly, but certainly is effective).  The power supply, mains lead and included VESA mounting plate are separated from the system itself by a cardboard divider and all of the individual parts (including the system) are enclosed in their own plastic bags to keep moisture at bay.  Once out of the bag, the unit proved to be very black, very shiny and of all metal construction (unlike the Beelink AP35 which I wrote about a couple of weeks back).  Offset screw holes prevent misalignmentIt looks very nicely made and well put together and it’s obvious that someone put more than a couple of minutes of thought into this very compact design (for instance, the bottom of the unit has ventilation slots and it is secured to the body with four, asymmetrically offset screws, so that it’s actually impossible to attach it in a way which would block those slots).

I ordered memory and an mSATA SSD module from Amazon here in Japan and actually got a pretty good deal.  If you do buy one of these units, it’s important that you only use the low-voltage (1.35v) variants of the DDR3 SODIMM, though; this system won’t work with higher voltage rated memory.

Here’s where I hit a very small speed-bump in the road to getting it all working.  It turns out that the motherboard slots are not identical.  You have a 50/50 chance of getting it right when installing the mSATA  …and I got it 100% wrong.

Nope, not this way!
Nope, not this way!

The right way round (R/H slot)
This way!!

As you can see, the mSATA module needs to be plugged into  the right-hand socket to be correctly recognized by the system.

Take another look at that “This way!!” photograph again.  The first point of note is the RTC battery (the yellow blob in the bottom, left-hand corner).  This system comes with an RTC and battery, which means any Unix-based OS works right out of the box; just tell the OS what timezone you’re in and you’re done.  Notice also the row of RJ45 sockets at the L/H side.  If you click on the image to get the full-sized version (it will open in a new tab), you can easily read the MAC address assigned to each port.  It’s probably worthwhile making a note of those (they’re sequential) while you have the bottom off, to help with identification later.

You can also see there’s  a SATA port available on the motherboard, but with this particular model there’s no space available to fit an internal drive.

Here’s a partial dmesg output from the machine once FreeBSD was loaded, showing the CPU features for the J3160:-

Copyright (c) 1992-2018 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 12.0-RELEASE-p4 b0ff15badd(RELENG_2_5) GENERIC amd64
FreeBSD clang version 6.0.1 (tags/RELEASE_601/final) (based on LLVM 6.0.1)
VT(vga): resolution 640×480
CPU: Intel(R) Celeron(R) CPU J3160 @ 1.60GHz (1600.05-MHz K8-class CPU)
Origin=”GenuineIntel” Id=0x406c4 Family=0x6 Model=0x4c Stepping=4
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA, CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
Features2=0x43d8e3bf<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3, CX16,xTPR,PDCM,SSE4.1,SSE4.2,MOVBE,POPCNT,TSCDLT,AESNI,RDRAND>
AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM>
AMD Features2=0x101<LAHF,Prefetch>
Structured Extended Features=0x2282<TSCADJ,SMEP,ERMS,NFPUSG>
Structured Extended Features3=0xc000000<IBPB,STIBP>
VT-x: PAT,HLT,MTF,PAUSE,EPT,UG,VPID
TSC: P-state invariant, performance statistics
real memory = 4294967296 (4096 MB)
avail memory = 4002127872 (3816 MB)
Event timer “LAPIC” quality 600
ACPI APIC Table:
WARNING: L1 data cache covers fewer APIC IDs than a core (0 < 1)
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
FreeBSD/SMP: 1 package(s) x 4 core(s)

Close to the end of the “Features2” line, you’ll see “AESNI” included.  These are Intel’s “Advanced Encryption Standard – New Instructions” which enable faster, hardware-assisted  encryption and decryption.  Although this technology is now available on some other processors (including ARM), older Intel processors don’t have it (for instance, the predecessor to this mini-pc system had a Celeron J1900 processor, which doesn’t have AES-NI), so a J3160 is worth the extra few dollars if you’re planning on a VPN server, for instance.

Last words

I actually got two of these systems, one for my own use (to replace an ancient firewall box) and one for a remote site.  They’ve now been running for almost exactly a year (since I began this article in early August, 2019) and have been totally reliable during that time.  I did think that the heat-sink was running a little bit on the hot side when I first installed them, but the “touch test” is deceptive and even during the mid-summer heat, the processors barely register 50°C.

The systems handle the traffic we pull through them without any problem and can handle multiple firewalled VLANs, encrypted VPN traffic and multiple physical networks with ease (as well as handling the normal associated processes — NAT, DHCP, DNS, NTP, etc).  I’d like to emphasize what good value these little systems are.  Not only is the initial purchase price very low, but the lack of fans and the 6W (avg TDP) processor mean the power requirements (and hence the monthly electricity bill) are low, too.  I was also very impressed with the quality of the (all metal) case, the general design and workmanship, as well as the packing and delivery from the vendor.  They may not be as cheap as a Raspberry Pi, but the quality of the case, included PSU, cables and accessories, as well as the RTC (and battery) and four GbE ports more than make up for that.  You won’t be running a 20TB database with 200 concurrent users on one of these machines, but for moderately light 24/7 operations for a good sized household or small business, I don’t thing you can go far wrong.