Tech in Plain Site: Finding a Flat Tire

There was a time when wise older people warned you to check your tire pressure regularly. We never did, and would eventually wind up with a flat or, worse, a blowout. These days, your car will probably warn you when your tires are low. That’s because of a class of devices known as tire pressure monitoring systems (TPMS).

If you are like us, you see some piece of tech like this, and you immediately guess how it probably works. In this case, the obvious guess is sometimes, but not always, correct. There are two different styles that are common, and only one works in the most obvious way.

Obvious Guess

We’d guess that the tire would have a little pressure sensor attached to it that would then wirelessly transmit data. In fact, some do work this way, and that’s known as dTPMS where the “d” stands for direct.

Of course, such a system needs power, and that’s usually in the form of batteries, although there are some that get power wirelessly using an RFID-like system. Anything wireless has to be able to penetrate the steel and rubber in the tire, of course.

But this isn’t always how dTPMS systems worked. In days of old, they used a finicky system involving a coil and a pressure-sensitive diaphragm — more on that later.

TPMS sensor (by [Lumu] CC BY-SA 3.0Many modern systems use iTPMS (indirect). These systems typically work on the idea that a properly inflated tire will have a characteristic rolling radius. Fusing data from the wheel speed sensor, the electronic steering control, and some fancy signal processing, they can deduce if a tire’s radius is off-nominal. Not all systems work exactly the same, but the key idea is that they use non-pressure data to infer the tire’s pressure.

This is cheap and requires no batteries in the tire. However, it isn’t without its problems. It is purely a relative measurement. In practice, you have to inflate your tires, tell the system to calibrate, and then drive around for half an hour or more to let it learn how your tires react to different roads, speeds, and driving styles.

Changes in temperature, like the first cold snap of winter, are notorious for causing these sensors to read flat. If the weather changes and you suddenly have four flat tires, that’s probably what happened. The tires really do lose some pressure as temperatures drop, but because all four change together, the indirect system can’t tell which one is at fault, if any.

History

When the diaphragm senses correct pressure, the sensor forms an LC circuit. Low air pressure causes the diaphragm to open the switch, breaking the circuit.
The first passenger vehicle to offer TPMS was the 1986 Porsche 959. Two sensors made from a diaphragm and a coil are mounted between the wheel and the wheel’s hub. The sensors were on opposite sides of the tire. With sufficient pressure on the diaphragm, an electrical contact was made, changing the coil value, and a stationary coil would detect the sensor as it passed. If the pressure drops, the electrical contact opens, and the coil no longer sees the normal two pulses per rotation. The technique was similar to a grid dip meter measuring an LC resonant circuit. The diaphragm switch would change the LC circuit’s frequency, and the sensing coil could detect that.

If one or two pulses were absent despite the ABS system noting wheel rotation, the car would report low tire pressure. There were some cases of centrifugal force opening the diaphragms at high speed, causing false positives, but for the most part, the system worked. This isn’t exactly iTPMS, but it isn’t quite dTPMS either. The diaphragm does measure pressure in a binary way, but it doesn’t send pressure data in the way a normal dTPMS system does.

youtube.com/embed/l0cY5sLySEE?…

Of course, as you can see in the video, the 959 was decidedly a luxury car. It would be 1991 before the US-made Corvette acquired TPMS. The Renault Laguna II in 2000 was the first high-volume car to have similar sensors.

Now They’re Everywhere

In many places, laws were put in place to require TPMS in vehicles. It was also critical for cars that used “run flat” tires. The theory is that you might not notice your run flat tires were actually flat, and while they are, as their name implies, made to run flat, they also require you to limit speed and distance when they are flat.

Old cars or other vehicles that don’t have TPMS can still add it. There are systems that can measure tire pressure and report to a smartphone app. These are, of course, a type of dTPMS.

Problems

Of course, there are always problems. An iTPMS system isn’t really reading the tire pressure, so it can easily get out of calibration. Direct systems need battery changing, which usually means removing the tire, and a good bit of work — watch the video below. That means there is a big tradeoff between sending data with enough power to go through the tire and burning through batteries too fast.

youtube.com/embed/aorDT-wGz2M?…

Another issue with dTPMS is that you are broadcasting. That means you have to reject interference from other cars that may also transmit. Because of this, most sensors have a unique ID. This raises privacy concerns, too, since you are sending a uniquely identifiable code.

Of course, your car is probably also beaming Bluetooth signals and who knows what else. Not to even mention what the phone in your car is screaming to the ether. So, in practice, TPMS attacks are probably not a big problem for anyone with normal levels of paranoia.

An iTPMS sensor won’t work on a tire that isn’t moving, so monitoring your spare tire is out. Even dTPMS sensors often stop transmitting when they are not moving to save battery, and that also makes it difficult to monitor the spare tire.

The (Half Right) Obvious Answer

Sometimes, when you think of the “obvious” way something works, you are wrong. In this case, you are half right. TPMS reduces tire wear, prevents accidents that might happen during tire failure, and even saves fuel.

Thanks to this technology, you don’t have to remember to check your tire pressure before a trip. You should, however, probably check the tread.

You can roll your own TPMS. Or just listen in with an SDR. If biking is more your style, no problem.

hackaday.com/2026/01/21/tech-i…

Словацкий паспорт занял пятое место в мировом «рейтинге силы»

barikada.sk/?p=22236

Рейтинг «силы паспортов» Henley & Partners
Положение на январь 2026 года

192 Сингапур
188 Южная Корея, Япония
186 Дания, Люксембург, Испания, Швеция, Швейцария
185 Австрия, Бельгия, Финляндия, Франция, Германия, Греция, Ирландия, Италия, Нидерланды, Норвегия
184 Венгрия, Португалия, Словакия, Словения, ОАЭ
183 Хорватия, Чехия, Эстония, Мальта, Новая Зеландия, Польша
182 Австралия, Латвия, Лихтенштейн, Великобритания
181 Канада, Исландия, Литва
180 Малайзия
179 США

Come passare al software libero: una guida pratica per le amministrazioni locali:
framadrive.org/s/9fdrtLbXocg8A…

Nicolas Vivant è direttore della strategia e della cultura digitale nel comune di Échirolles vicino a Grenoble, nel corso di alcuni anni il comune è passato al software libero. Alle Journées du Logiciel Libre (Giornate del Software Libero) tenutesi a Lione il 24-25 maggio 2025 Vivant ha fatto una presentazione, basata sulla sua esperienza, che è un vero e proprio manuale pratico (18 pagine) per le amministrazioni locali che vogliono affrontare il passaggio al #SoftwareLibero. Nel link trovate la traduzione italiana della trascrizione. Mi è sembrato un documento utile anche per il contesto italiano. #AmministrazioniLocali #Linux #LogicielsLibres #traduzioni

La condivisione di questo manuale è più che gradita 😃

@maupao
@informapirata
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@ItaLinuxSociety
@devol
@fedimedia
@linux
@lealternative
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@openiteste
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Un grand merci à
@nicolasvivant
et
@Marie_Odile_Morandi del gruppo Trascrizioni di @aprilorg

Espressif Introduces the ESP32-E22 Wi-Fi 6E and Bluetooth Co-Processor

Espressif has unveiled its latest major chip in the form of the ESP32-E22. Officially referred to as a Radio Co-Processor (RCP), it’s intended to be used via its PCIe 2.1 or SDIO 3.0 host interface to provide wireless communications to an SoC or similar.

This wireless functionality includes full WiFi 6E functionality across all three bands, 160 MHz channel bandwidth and 2×2 MU-MIMO, making it quite a leap from the basic WiFi provided by e.g. the ESP32-S* and -C* series. There is also Bluetooth Classic and BLE 5.4 support, which is a relief for those who were missing Bluetooth Classic in all but the original ESP32 for e.g. A2DP sinks and sources.

The ESP32-E22 processing grunt is provided by two proprietary Espressif RISC-V CPU cores that can run at 500 MHz. At this point no details appear to be available about whether a low-power core is also present, nor any additional peripherals. Since the graphics on the Espressif PR article appear to be generic, machine-generated images – that switch the chip’s appearance from a BGA to an LQFP package at random – there’s little more that we can gather from there either.

Currently Espressif is making engineering samples available to interested parties after presumed vetting, which would indicate that any kind of public release will still be a while off. Whether this chip would make for an interesting stand-alone MCU or SoC along the lines of the -S3 or -P4 will remain a bit of a mystery for a bit longer.

Thanks to [Rogan] for the tip.

hackaday.com/2026/01/21/espres…