• Hypercube. How we gave developers test devices without losing any

      You can’t properly test and debug mobile apps without test devices, which there should be plenty of considering how the same code may behave differently on different models. So how do we keep track of these devices? How do we quickly provide developers and testers with the smartphones they need, configured the way they need, and without much red tape?

      I’m Alexey Lavrenuke. Over the years, I’ve worn many hats: one of the authors behind Yandex.Tank, a speaker on load testing, and the guy who calculated energy consumption by mobile phones. Now I’m a Yandex.Rover developer on the self-driving car team.

      After the phones and before Yandex.Rover, there was Hypercube.

      A few years ago, the head of mobile development popped in to the load testing department and mentioned a problem they were having with test devices: phones had a tendency to inexplicably migrate from one desk to another. Picking the right device and then finding it had become a challenge. We already experienced working with mobile devices from building a digital ammeter to calculate energy consumption, so we decided to help our coworkers out and quickly rig up a handy contraption. We figured the whole thing wouldn’t take more than three months. Oh how wrong we were. Let me tell you what we were really in for.


      ''Dallas cube''
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    • Writing a laptop driver for fun and profit, or How to commit to kernel even if you're not that smart

      • Translation

      Where it all began


      Let’s start with our problem statement. We have 1 (one) laptop. A new, gamer laptop. With some RGB-backlight on its keyboard. It looks like this:

      image
      Picture taken from lenovo.com

      There’s also a program installed on this laptop. That’s the thing that controls our backlight.

      One problem – the program runs under Windows, and we want everything to work on our favourite Linux. Want LEDs to flash and those pretty colours to blink on and off and such. A natural question arises, can we do all that without reverse-engineering and writing our own drivers?

      A natural answer arises, no. Let’s open IDA and get cracking.

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    • AHURATUS Smart Home Voice Assistant

      N|Solid


      N|Solid


      AHURATUS Smart Home Voice Assistant


      Developed by Ehsan Shaghaei
      Innopolis University
      AHURATUS Scientific Club.

      STM32F103ZET6 UNIVERSAL BOARD


      Introduction


      AHURATUS Smart Home Voice Assistant is an IOT device developed in order to control other home devices by voice detection. Note: This device is made ONLY for academic purposes.


      Approach


      Description


      "AHURATUS Smart Home Voice Assistant" uses an ARM Cortex-M3 process for running the instructions as well as several peripheral devices in order to decrease the complexity of data bus and RF-Circuit calculations.


      Bill of Materials


      # Component Name Role Technical Document links
      1 STM32F103ZET6 Process and Control Datasheet
      2 HC-05 Bluetooth Module Bluetooth Radio Connection Datasheet
      3 220-5V AC-DC Adapter Powering the circuit Datasheet
      4 LED or Mosfets or Relays To System Output Datasheet
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    • Optimising server distribution across the racks

        Recently, a colleague asked me in a chat:

        — Is there an article how to pack servers into the racks properly?

        I realised that I'm unaware of it. So, I decided to write my text.

        Firstly, this is an article about bare metal servers in the data centre (DC) facilities. Secondly, we estimate that there are a lot of servers (hundreds or thousands); the article doesn't make sense for fewer quantities. Thirdly, we consider that there are three constraints in the racks: physical space, electric power per each one, and cabinets stay in the rows adjacent to each other, so we can use a single ToR switch to connect servers in them.
        The answer to the original question depends significantly...
      • TOKEN2 Molto-1, world's first multi-profile TOTP hardware token

          imageOur new product currently being finalized, the Token2 Molto-1, will expand on our technology by now supporting up to 10 Time based One-Time Password (TOTP) profiles. Earlier this year, with the miniOTP-2, miniOTP-3, and C301 we introduced the world’s first programmable TOTP tokens with time sync. The aim of these products was to provide a solution to the time drift that affects hardware tokens. We didn’t want to stop there, though! We also recognize the desire for multiple profiles which is why our latest product is a programmable multi-profile hardware token, called Token2 Molto-1. The clue is in the name, at least for anyone who understands Italian — “molto” is “many” in Italian. Having a multi-profile programmable hardware token means you can have only one device for up to 10 of your accounts.
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        • Tech Insights: Are LED filament-lamps so good?

          • Translation
          Saluting my LED lamp fans!

          Today we will talk about the palpitating and extremely popular subject in recent years — filament LED (Light-Emitted Diode) lamps. Numerous articles have been published here on Habr (1, 2, 3) and on the web, but none of them tells us a word about in-depth analysis of the lamps (what is actually inside) and comparison of their temperature characteristics. Therefore, especially for you — my dear LED-lovers — I conducted a detailed analysis of such lamps from different manufacturers, including temperature measurement of LEDs themselves.

          Afterwards we will try to answer the question: are filament lamps as good as marketers present them to us?

          Disclaimer: this is my very first attempt to translate and adopt an article from Habr into English, so I will ask you to give a fruitful feedback and correct some mistake if any present.
          Shock, thrill and scandals!
        • Independent Tests of Baikal-T1 — the first Russia's 28 nm SoC — and BFK 3.1 Evaluation Board

            Tech journalist Igor Oskolkov of 3DNews.ru has recently tested publicly available version of the evaluation board or, as the vendor calls it, the developer software-hardware complex, under the code name BFK 3.1 with the Russian SoC Baikal-T1 based on the MIPS P5600 Warrior architecture. Here goes the English translation of his text, that was first published in Russian by servernews.ru.
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          • AdBlock has stolen the banner, but banners are not teeth — they will be back

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          • Flightradar24 — how does it work?

              I’m going to hazard a guess and say that everyone whose friends or family have ever flown on a plane, have used Flightradar24 — a free and convenient service for tracking flights in real time.



              But, if my friends are any indication, very few people know that the service is community-driven and is supported by a group of enthusiasts gathering and sending data. Even fewer people know that anyone can join the project — including you.

              Let’s see how Flightradar and similar other services works.
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            • System in Package, or What's Under Chip Package Cover?

                Transistor feature size is decreasing despite constant rumors about the death of Moore’s law and the fact that industry is really close to physical limits of miniaturisation (or even went through them with some clever technology tricks). Moore’s law, however, created user’s appetite for innovation, which is hard to handle for the industry. That’s why modern microelectronic products aren’t just feature size scaled, but also employ a number of other features, often even more complicated than chip scaling.


                Disclaimer: This article is a slightly updated translation of my own piece published on this very site here. If you're Russian-speaking, you may want to check the original. If you're English-speaking, it's worth noting that English is not my native language, so I'll be very grateful for the feedback if you find something weird in the text.
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