Headworx

The post on  Bluetooth NLC vs DALI+: Capacity and Performance has generated very valuable feedback. I promised to shed some more light on my network capacity calculations, so here they are. The key assumptions are: - The Thread network operates at 2.4GHz using IEEE 802.15.4 data links at 250kbps; - Transmitting nodes use Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) method to manage the shared communication channel; - Each unicast transmission is acknowledged - There are two hops (say: sensor → router and router → lighting controller) - The minimum data frame at PHY is 50 octets (+6: preamble + SFD), so ~1.8ms - The ACK frame (including the SIFS time) is ~0.5ms - The average CSMA/CA overhead is ~1.4ms That gives us 3.7ms per hop total. So with two hops we have the channel occupancy of 7.5ms. At full 100% channel occupancy that would give us capacity of 135 end-to-end messages per second (one way). But... 100% would simply kill the network. Thread is very fr...

Whenever I come across a discussion that involves wireless communications over the Thread protocol (such as this one ), there is almost 100% chance people don't understand the underlying physics and traffic patterns. This is the result of Thread marketing since 2014, highlighting the IPv6 protocol as its key strength. And typically it goes like that: "Thread is based on IPv6 and there are more IPv6 addresses that grains of sand in the Universe". And people read this "because Thread is based on IPv6, it is a highly scalable wireless protocol". Treating the potential number of static addresses equally to the dynamic situation when these devices actually send data. If we consider the networked lighting control domain, the most prevalent pattern today is to have a motion sensor in every luminaire. The motion sensor usually has multiple functions: it is a motion sensor of course. But it also is a light level sensor enabling daylight harvesting (or dimming lights down...

Once considered the greatest thing since sliced bread, notifications have spun of of control. Meant to be the (most) important stuff, have been sliding into complete irrelevance. And have become totally distracting and annoying. The operating systems (including the flagship Android and iOS), even with their recent Artificial Intelligence (AI) features have failed to cope with the notifications' torrents. Out of box, every app wants to send notifications about everything - this is of course the fight for potential revenue through engagement and conversion. Yes this can be managed. But only theoretically, as users really drown in the ocean of options they do not understand. On top of the notifications' options there is the hierarchy - you have favorite contacts (meant to always go through), you have time - or activity - based profiles (iOS calls them focuses). Barely anyone understands the combinations. Then there are the super annoying users of (increasingly more popular) instan...

I really liked the Lex Fridman's recent interview with David Heinemeier Hansson (aka DHH) - the 37signals / Ruby on Rails guy. Many topics, but the small teams theme has really resonated with me. I was a solo programmer for about 20 years, starting with Sinclair ZX Spectrum in 1983 and going through several jobs including the company I cocreated in 1992, which grew up to around 300 people ten years later. This solo experience has spoiled me. I was the product manager, the ux designer, the architect and the coder. And that was extremely efficient. Of course the solo approach has limits to the scalability, as there are only 2 hands and 24 hours in a day, no matter how much money you throw in. So at some point I had to give up and cede the tasks to the team. And that was so immensely frustrating. Despite the team being many developers (I still tried to keep the architect role), things started going super slow. I was spending countless hours teaching, explaining, then explaining again ...

Utilities move slowly. But ultimately they do. Half a year ago I installed the Home Assistant multi-channel energy meter which has  clearly shown the energy usage patterns. I had known before my addiction to hot bath every day cost me dearly. And it was really the lowest hanging fruit. Water boiler is the most efficient and available energy storage . After seeing the usage patterns, I was planning to switch to variable energy pricing plan. But filling the related paperwork was tedious enough to procrastinate. Until the utility offered the helping hand: switch to energy pricing with just a single "yes" click on their web site. No paperwork, no nothing.  A couple of days later the confirmation of the switch arrived. Plus I have online access to the formal energy meter readings. No Home Assistant integration yet, but the patterns and values match with what I have, which is reassuring. I need to get used to this a bit (although the main patterns have already been preprogrammed)....

This one is quite interesting and I am yet to collect the hard evidence on what really happens. Long story short: Home Assistant can, behind the scenes, drain battery in a smart watch. It all leads back many months ago when I started seeing my Garmin fēnix  watch dead every morning. I mean ALMOST every morning. Normally it can run for 1-2 weeks on a charge and suddenly every morning it was dead, despite being fully charged on the day before. I tried different things - software/firmware update of course, changing some parameters (but it had been working fine before) - no lasting improvement. Until this June (after having extensive travel period - US West Coast, twice to China and then Europe), when I realized that it did not lose the battery when I was away from home. I started thinking on what was so special at home that the watch, left for the night on my bedside table, was losing the charge completely. There was one idea that came to mind: Home Assistant. And to be precise: ...

It has been almost 6 full months since (after long procrastination) I finally completed the home energy monitoring project . In short: Home Assistant + Circuit Setup energy meter based on ESPHome. Long story short: all has been working flawlessly. There have been multiple routine firmware updates (they are released ~monthly). To be honest I have not paid (almost) any attention to them. Luckily nothing got broken, but equally Home Assistant could be releasing one update per year. This is a side observation, but generally people are fed up with software updates. Even if they go flawlessly, there is always the risk of something getting broken. I've been hearing the same from our customers: you release too frequently (we used to every 6 months, but now there is the pressure to release at most once a year). Ove the 6 months I have learned quite a lot about my usage patterns. Daily hot bath is an energy hog, but I can easily run the boiler when the energy is least expensive (=middle of ...

High speed trains in China are phenomenal. I could sit by the window for hours watching the passing landscape. They do not run on ground. They either soar high on concrete bridges and piers or pierce through tunnels. It is thousands of kilometers of piers and tunnels. And the landscape mostly flips from agricultural fields to endless seas of industrial buildings - factories. It is totally unlike anywhere else. When the train enters an industrial zone, there are thousands and thousands factories. It probably takes such a train ride to understand the hypothetical effort of moving manufacturing to the West. The factories form a unique and super efficient industrial supply chain. It is not about the iPhone. While a flagship symbol of Western dominance, we could do without iPhones. But probably we could not do without lights, linen, pots, just about every daily used item is made in China. And then there are basic components to make them: wires, bolts, glue, paint. And then the raw materials...

In this last part (so far) of the Getting Around in China mini-series I'd like to share tips on personal mapping and navigation software. Actually this is a one big tip. The Gauda / Amap mobile application. In different markets (app stores) it goes by different names, so search the app store for either Gauda or Amap. This is the go-to replacement for Google Maps or Apple Maps. While both Google and Apple work to some extent in China, their functionality is severely limited. They will not find you any public transport options and even basic driving / walking functions are limited. Also in several interesting areas Amap offers very interesting options not available in any app in the Western hemisphere. Driving in underground garages. I still need to explore the technical side of this, but the long story short is Amap can navigate in underground garage structures. Clearly no satellite reception there, so I suspect Bluetooth beacons may be at play. Nevertheless you will appreciate the ...

The terrifying crash of the Air India flight 171 in Ahmedabad has ignited a number of theories on the cause of the accident. The plane took off and went down immediately as it appeared to lose thrust in both engines. Today's aircraft are considered very safe. The key for the safety record is redundancy of all critical systems. Everything is doubled or tripled or quadrupled. From the probability theory perspective, multiplying the critical components vastly reduces the chance of a total failure, as the individual equipment unit failures are considered to be independent. That is mostly true for legacy / mechanical components. An engine blade failure in one engine does not cause the other engine to fail. Or a chance of two blades (one in each engine) failing at the same time is practically zero. But it turns out when software is involved, equipment failures can be fully synchronous. Which I believe is what happened in this accident. In the Boeing 787 Dreamliner, the fuel pumps are el...

In this third episode of the China: Getting Around mini series I'm going to share tips about long(er) distance travel in China. So far we have already covered passports, eSIM data in part 1 and translation apps, mobile payments, WeChat and DiDi in part 2 . Airlines. There is not much special about how airlines work in China. Buy tickets online, show up for check-in etc. There are some differences related to items allowed in a carry-on bag. For example foldable walking poles are not allowed. So are not multi-tools designed as so called "TSA-safe" (from my experience, they are not in Mexico either). As they say "a tool is a tool and tools are not allowed". Period. Cigarette lighters are prohibited too, and there is an interesting solution - you drop the lighter before security in a box and that box then goes to the security exit door where disembarking passengers can grab lighters.  Trains. High speed trains are what China is really famous for. The network is inc...

You have the passport and a phone with the internet on it. What is next? Translate. Unless you speak Mandarin, a language translator app in the next on the list. Language has been a barrier, but translator apps break through that barrier. Use the one you like. I use Google translate. It is prudent to download the languages for offline use. Once done you can either type or dictate (or have someone else dictate) or use camera for instant translation of signage or restaurant menus. The apps are not perfect (yet), but they do a really good job. On one of the past trips, for example, we were able to negotiate a set of medicines in a pharmacy. The pharmacist was asking many questions in Chinese, us answering in English, and ultimately the medicine worked very well. Payments. As I mentioned, China has its own preferred payment systems. Credit cards would not work in most cases. Maybe in higher end hotels. But the default means of payment is by presenting or scanning a QR code. The app I use m...

I never thought I would become an expert on China and I'm still far from being one. But our business relationships with Chinese partners have been growing strongly and that is reflected in much more frequent China trips. So here is the mini series of blogs with some tips which you may find helpful. China is not straightforward for Western visitors. It is just different and small things matter when preparing for a trip. Or just knowing what to expect. May marks my second trip to China in 2025 an I plan to be here back in June. What is different is I'm the first time on my own, which I find both exciting and liberating. Being able to do things on my own has always been important, be it soldering a PCB or writing a piece of assembly code or trekking in the mountains of Georgia or Kirgizstan. Organized trips and telling people to do things for you or carry your bags is simply not my style. So you are going to China - where to start? Passport. Obviously the number one step is making...

SILVAIR published the Q1-2025 report on May 15th. Bound by the corporate governance rules I could not share our progress earlier, but now the cat is out of the bag. We had a stellar quarter. Q4-2024 was record and always in such cases the worry is if the trend would continue. It has continued. Even stronger. Despite the US trade wars introducing uncertainty in the markets. Fundamentally I think there are couple of jointly contributing factors to our overall progress: Brand recognition. Despite very low marketing budget, we continue to be increasingly more recognized. And this is both Bluetooth NLC as the only truly interoperable wireless lighting control standard, and Silvair as the leading product based on this standard. Both brands are associated with performance, quality, robustness and ease of use. A perfect combination of features. The product feature set is increasingly more complete, particularly addressing the needs of customers in the enterprise segment. Network scalability ha...

The news of Enlighted shutting down the lighting controls business have been a real earthquake for the industry. Once the absolute champion and the leader in the lighting controls and IoT space has ceased to exist. Sadly, they have not been the first ones. There was Universal Douglas in 2023  and  Touché in early 2025 . But the Enlighted case has really transformed the company name into a verb. In a very bad way: "to be enlighted" almost feels in line with "to be musked": "to be musked" can mean to be treated poorly or "screwed over" by a company, often without apology. For example, buyers of Tesla vehicles might say they were "musked" if they experienced unresolved issues with their cars. This is a play on Elon Musk's surname and is used pejoratively. So have you been enlighted? We can help. The common theme across all the above mentioned "gone out of business" events is - they all were proprietary / vendor - locked solu...

Push notifications are now everywhere and apart from being super annoying, they have really become useless. By default every app (and most web pages too!) try enabling all forms of notifications by default and it takes a lot of fluency in handling phones and computers to set them up properly. Which mostly means "disable". I think the time has come to really reverse the defaults. They should be "do not notify me about anything". And then users would be able to select the small set of really important things they want to be actively poked about. The problem has gotten even worse as most apps / services are multi-modal - they live on PCs, phones, watches, even in earbuds. And a single event gets multiplied by being pushed to all the devices. Then some services, apart from sending a notification send an email. Which sends a notification f its own. Shopping and payment apps are the worst. "we have received your order" - "we have started processing your pay...

The wireless CarPlay was working great. Until it stopped. Did not stop completely, but started losing the connection, freezing, or not connecting at all. Interestingly, I installed the Ottocast wireless adapter exactly to solve similar problems with the wired USB connection. The hypothesis (never firmly verified) was that there was too high temperature-related clock oscillator drift in my Pioneer head unit : a cold iPhone would not connect to a sunbaked in-dash radio. So the Ottocast solved the problem (perhaps by being equally "baked" with Summer sun rays and thus drifting the oscillator in the same direction, or simply by being less strict on USB timing, compared to the iPhone). That was Summer 2024. Come Autumn and Winter, and the stable configuration started behaving less stable. Freezing screen, erratic updates, not connecting at all, or disconnecting and reconnecting in a loop). Of course the iPhone was the last suspect on the list. I was checking connectors, software ...

It is still winter(ish) here and there but some of the Spring days are really really nice in April. Perfect time to try some new activities.  Actually I learned the packrafting idea during the 2024 New Zealand trip. A packraft is like a pontoon, but smaller, better shaped, and can be quite light. You put it in a backpack, go for a mountain hike and then raft down a river. Can be quite extreme, but it is all a choice. Packrafts are perfect for slow rivers, lakes and fiords too. The one I bought (seen on the photo) is a tad above 2 kilograms. On top of that you need a paddle (a carbon one while expensive, is super light). It folds down to a size of a bear canister so can be strapped to any backpack. You can save on weight by not carrying a sleeping mat - turn the raft upside down and lie on it. Also a simple tarp is sufficient instead of a tent. A pyramid-shaped tarp can be set up on the paddle. There are a bit bigger rafts which allow carrying a bike. And then you call the think bik...

Tesla discussions have always brought very polarized opinion. Either trash and going bankrupt or the absolute leader in AI about to deliver autonomous driving (Full Self Driving - FSD) through a simple software update. My point today is really not about Tesla but about the value of FSD in general. I wrote about this many times, with the Tyranny of Convenience being the most popular post. Today the theme is similar. It is about the concept of "enough" which is one of the key enemies of capitalism. Prospering capitalist economies (the USA being the prime example here) absolutely depend on creating and expanding consumers' desires. People must want more for the wheels to spin. And the vision of consumers even remotely calling "we have enough" is the most feared. "Enough" must be eliminated. In many ways I am a person who has enough of many things. Sometimes I even feel that my level of "enough" is definitely too high. I try not to chase new car...

I am a bit paranoid about backups. That includes planning for a backup gear when going on a multi-day remote hikes. On one hand it is really prudent to take as little gear as possible to travel light and thus reduce the risk of orthopedic injuries. Unfortunately there is no way to take backup ankles and knees... Smartphones - even if out of network range - are great in combining multiple functions in one device - a camera, a map, a satellite locator, a notepad, a book reader, a chess board, a music player etc. But no matter how good they are protected, there is still the elevated risk of damaging the phone on a trek. A simple screen crack may render the touch function inoperable and the whole device suddenly becomes useless. There is one other aspect to phones - they run out of batteries and are not ideal to use in full daylight. Displays get better, but for true daylight use like reading books, we still use Kindles. But then Kindles are limited in function - no maps, no GPS, cannot be...

iPhone photography is great and it is clearly now my main camera. As the old saying goes - the best camera is the one you have with you. And it also makes very good photos. Purists will argue that a large aperture prime lens cannot be matched (and I agree) but a large aperture prime typically weighs 1 kilogram or more (and requires an equally heavy camera). So it is impossible to have a lens like that at hand all the time. One thing the iPhone (and most smartphones in general) lack is a long telephoto. Yes they have an equivalent of 70mm or even 120mm but there are certain "telephoto moments" when there is no substitute for a really long lens. I have been on a quest to find a lightest and most pocketable long lens setup for a long time. And we are talking about focal lengths of 400mm or more. Have tried different setups, such as the Ribcage - modified Sony DSC-RX0 , but nothing has worked well so far. Playing with the DSC-RX0 I realized I really needed a viewfinder to properl...

I was running Windows 10 for, well, close to 10 years. Since it's original release in 2015 almost till the end of 2024 when I had the motherboard in the 2018 MacBook replaced. It was the original install which then survived two Lenovo laptops and was then cloned to the MacBook. Unlike the older Windows releases (the unfamous Vista and earlier), Windows 10 has never suffered from the problem of getting slower with use. And it was super stable. The motherboard replacement triggered me however to perform a clean install of Windows 11 , prompted mostly by the Windows 10 line nearing its end of life, meaning mostly the end of support and security patches. There was the initial disappointment of not being able to move the taskbar to a vertical position (most monitors today are wide, so it really really makes sense to have the taskbar on the side), but other hat that Windows 11 runs just fine. Overall cleaner here and there but generally the experience has been as great as can be. There a...

I have finally decided to pull the trigger and get myself a pair of Apple Airpods (Pro 2). The key motivation has been to get a set that is comfortable for daily runs while providing decent sound isolation. It the past I praised the virtues of the non-isolating headphones. I still use the Bose Frames on my trail runs at home. But these runs are in nature's sanctuary: it is just me and the woods and some wildlife. I also absolutely love the bone-conducting Shokz with a boom mike for teleconferencing. They sound fabulous (on both ends of a teleconference). And I also have Bose Earbuds which I use when flying - still nothing comes close to Bose when noise canceling is concerned. But they don't feel quite right when running. One reason that had prevented me from buying the Airpods in the past was the white color. They just look like you have cigarettes sticked in your ears. And per the Apple / Ford rule you can have them in any color as long as it is white. But there is a soluti...

I blogged in the past about my love-hate relationships with Bluetooth products and Logitech was brought as the example of a company that maintained technical excellence while losing on the support / delivery side . I was still bringing the excellent product aspects of the KEYS-TO-GO 2. That opinion was based on my initial product experience. After several months of using the keyboard on a daily basis, I must unfortunately admit the product is not so great after all. As a matter of fact it can be quite annoying (but there are workarounds). The key problem (pun intended!) with KEYS-TO-GO 2 is it is powered by coin-cell batteries. And the batteries die quickly and without any warning. The power consumption is not as bad as the other Kickstarter keyboard I had in the past . But still since purchasing the keyboard 9 months ago, I had to replace the batteries 3 times. That means batteries last for 3 months on average. That is a far cry from the advertised 3-year lifespan . Although, to be fa...

There is no doubt the leading social media platforms influence and shape peoples' opinions globally. Elon Musk was criticized for overpaying for Twitter yet this gamble clearly played out as he is now able singlehandedly command millions across the world, making him probably the most influential person on Earth. But Twitter is of course not the only game in town. There are the well established Facebook and LinkedIn, and for those hoping for more neutrality there is BlueSky and Substack. I'm a member of both platforms, but mostly passive. I have been circling around Substack trying to understand what it is and if I should become more active there. It seems many notable people I respect have found their home there. But the key question is how the social media landscape looks like in 5, 10, or 20 years from now. This blog has been around for 20 years and despite not being promoted, difficult to find, and not very interesting, has had a steady stream of followers. People who are mo...

5G (cellular data) generally beats WiFi. That is my conclusion after the recent travels in Asia and North America. Public WiFi has aged. In most places it has probably stayed at the 802.11g (50Mbps) while 5G is typically 5-10x faster. On top of that the WiFi backhaul in many places is slow too. And very often has many restrictions. Of course 5G costs (some) money and WiFi is theoretically free. But then you probably remember that meme where "no internet" and "fast internet" are smiley while "slow internet" is the angry face. Which is very true. Speaking of WiFi restrictions - some are well known and kind of obvious (like Google services being blocked in China), so for a westerner entirely reliant on GMail, Google Maps, etc., a roaming eSIM data plan is probably a must. Also WiFi is probably the only technology thing in China which is universally bad. Budget hotels, premium hotels, factories, offices - all are slow (and restricted). 5G on the other hand is ...

I generally stay away from loyalty programs. It simply feels like having more freedom of choice when you are not by default confined to just one brand. But there is one exception - the frequent flyer program run by United Airlines, who are a member of the Star Alliance. The reason is I do fly a lot, and most of the connections from/to my home town are served by Star Alliance airlines: LOT, Turkish, Austrian and Lufthansa. That is - of course - when you do not count the European low cost behemoths: Ryanair and Wizz. Intra-Europe destinations are typically best served by the two. Yes I know people complain a lot, but this is a typical whining to get more clicks. Because - to be honest - the low cost airlines deliver just awesome value for money when you fly point-to-point. There are no transfers and the flights are typically very short so the tight legroom does not matter. Things are different when there are no direct flights, which typically is the case for any intercontinental trip. Th...