Headworx

In the previous myth-busting episode on DALI I covered the polarity aspect of the DALI bus. That is: in theory it is polarity-free (it does not matter which cable goes where as far as the DALI line cables are concerned), and it practice the polarity matters (remember to connect DA+ to DA+ and DA- to DA-). This week I'd like to talk about DALI application controllers. DALI in principle has the concept of "control gear" and "control devices and application controllers". Again, the name (especially the distinction between a "gear" and a "device" is not intuitive. So lets try that: a gear is a driver. A device is a sensor or an application controller. The technical difference is much clearer. Drivers never transmit any data on their own. Only in response to a query command. Devices do the opposite - they send data on their own. So an application controller can send a dimming command to a driver. Or an occupancy sensor can send data whenever it d...

The DALI (Digital Addressable Lighting Interface) standard has had a very uphill battle in the USA. Lots of resistance, mostly quoted to it being problematic and expensive. On the other hand DALI has almost 100% market share in Europe and similarly in Asia and Middle East. DALI Alliance has been trying to change this, addressing the North American market with several campaigns, but they have not been too successful so far. And the reason is, despite DALI being a very good technology, there are many misconceptions, false myths, contradictory statements (even by the DALI people themselves). Here I'll address some key concepts that people often get wrong or are falsely propagated even by those who should know in the first place. DALI is polarity free. I have heard this so many times. Even from the founding fathers of DALI. So yes, in principle it is, but in practice it is not. DALI bus signaling works by shorting the bus. There are two wires and there is small DC (around 18V) current ...

Fast forward 20 years and the old battery drain problem is still with us. Perhaps the consequences are even more annoying, as we rely on battery-powered devices (phones) 24/7. In 2006 it was Windows Vista. Now it is iOS. I rarely use flight entertainment systems, turning to my own screen most of the time during flights. My go-to app is YouTube in offline mode. During regular office days I flag various videos as "watch later" and have the app setting to have them downloaded in the background, so they can be watched offline. This worked for me well for many years. But recently (I think I first noticed this in January this year) my phone started draining the battery very fast in flight. Looking here and there I traced down the problem to the YouTube app. Yes it was draining the battery very fast. So fast that the phone was becoming quite hot, which was unusual for an iPhone. Have tried different solutions, playing with a number of YouTube app settings and nothing has really wor...

My recent effort to cut down noise that manifests as a continuous avalanche of notifications on a phone has been quite successful. The phone is mostly silent, the watch does not vibrate and the earbuds do not interrupt audiobooks to play announcements. I only get a handful of "beeps" per day and they only come from a couple of selected contacts and apps I really do care about. Apps generally abuse the notifications mechanisms in a big way. Rendering the notifications' mechanism practically useless. So I went through all of them, disabling notifications and also making sure they use location services only when an app is active / in the foreground. What was not immediately obvious to me, was that the functionality of an app to stay connected over Bluetooth to an accessory (such as a watch) depends on the "location" permission to be "always". It does not explicitly say "Bluetooth", but iOS ties Bluetooth access with "location". My par...

Find My is one of very useful features of the Apple ecosystem. The way it works is devices broadcast Bluetooth beacons that can be picked up by other devices that forward these beacons to the Apple cloud, after attaching location tags to the beacons. Thus, assuming there are random iOS devices close to your items, you can track the items globally. A similar system is available in the Android ecosystem - the Find Hub. Just recently Google has upgraded the feature, allowing phones that are powered off, to be found. iPhones have had this since iPhone 11 (the U1 chip). The idea is simple - continue broadcasting Bluetooth beacons even in the off mode. Bluetooth broadcast use almost no power, so this broadcasting could be almost indefinite. Maybe not literally indefinite, but at least couple of months. The Insta360 Go3s camera I lost when descending from Mt Aorai in October 2025 , has come to life just recently (it has been 5 months now). It disappears for a couple of days and then reappears...

USB Type-C (usually referred to as USB-C) chargers support a fairly sophisticated protocol for selecting charging voltage and current. What is important, when nothing is connected to a USB-C port, no power is provided. The device that wants to be charged must tell the charger what it wants. Otherwise no charging takes place. This is designed so for may reasons, but the simplest explanation is: a connected device may not want to be charged at all: imagine using a USB-C cable to connect one charger to another charger. If there was any voltage present by default, the result could be catastrophic. The simplest way to tell the charger to offer the default 5V (as in USB-A legacy chargers) is to use the so-called Dead Battery mode. This is described in Section 4.8.5 of the Type-C specification. The device that wants to be charged (known as the Sink) must apply 5.1kΩ resistors to both CC1 and CC2 lines (pins). The term Dead Battery (from the Type-C specification perspective) describes a device...

I have a truly love-and-hate relationship with my Garmin watch. I love it for the looks. And for keeping record of my daily trail runs. And for holding backup topographic maps of (almost) the entire planet. And for being the flight computer on long distance flights. Actually the last part is also a contributor to the hate part. As it keeps the location track in flight through combined satellite readings, it also updates its time to the GPS time. And a time zone with it - meaning it always shows accurate time for the current location. Which is useless when you are just a passenger. You wake up in the night, look at the watch - it shows time, but at a glance you just don't have an idea in which time zone you are in. Yes, there is always 1pm somewhere on Earth. But generally when flying, the best way is to have either the departure time zone or the arrival time zone, not something in between. A phone use to be then a much more convenient time source - just showing the departure time z...