This time just a quick info. I just published library of KiCAD footprints that I made recently for my new project. The project itself has not been published yet and I want to keep it that way until I get first working prototype (what I hope will happen really soon). Meanwhile I am publishing this small library of footprints that I made for it with perspective of extending it in future with other hardware projects.
Still this is quite new topic for me as I have no electronics education, nor professional experience, so there is still a risk that I may fail at what I do and abandon such kind of projects. But for now, I just finished validation of footprints published here with a board that I ordered from JLCPCB, so you are guaranteed that they are fine (except one marked explicitly as such). Continue reading “My small library of KiCAD footprints”→
Few months ago I wrote a tutorial about creating Linux distribution consisting of just busybox as its userspace. In the meantime I worked a bit with docker and it sounded like nice next step in learning docker to automate the process of creating Linux distribution using it. As a result, today I present Linux distribution built with docker and based on my previous tutorial. I called it busy-linux due to it consisting of only busybox at the moment. My plan is to develop it further, most likely for private purposes only, so there might not be much happening in the project, but for sure I want to create dynamically linked variant in the near future, as this is what my use case requires. In the meantime feel free to try it yourself. Continue reading “Creating one-file Linux distribution with docker”→
Bluetooth application in AOSP hardcodes strange constraint in form of whitelist of MIME types that are allowed to be received. Also LineageOS seems to have that code compiled for some reason. There is no other way to allow any file transfer than to make your own Bluetooth apk and install it. In this tutorial I will show how to recompile APK and install it in system.
The fact that Android knows a lot about its user and don’t keep that information for itself is quite well known. But how much data is sent to the outside world on first connection to WiFi? Which apps are responsible for pushing the data into the web? I will try to show that on example of Xiaomi Redmi Go.
For the purpose of the test, I created network that is not forwarding any packet outside. Before performing the test I installed few APKs. Only one is known to contact strange servers – File Manager (com.rhmsoft.fm). I marked them with (*) on a list. Rest should not have any influence on the results. They were: Termux, AFWall+, F-Droid, Magisk and Aurora Store. Continue reading “How Android smartphone is spying on you?”→
Long, long time ago, before prices of inkjet and laser printers fell to levels allowing home users to own and use them, there was a primitive printing technology called dot-matrix. As any technology of the past, it is not competitive anymore. However it still has few advantages and one of them is reliability of these devices. Some time ago I found quite a cheap Oki 3321 printer that has 9 pin head and is capable of printing on A3 paper in portrait orientation. Usual mode of printing for these devices was simple text mode, where you just were writing your text in ASCII (or any weird coding popular in your country of origin) to its parallel port. Fortunately these printers usually had also graphic mode, where you could fully use capabilities of the device.
I already was experimenting some time with my device, so I already know it uses Mazovia variant (with zł as single glyph) as its codepage. I was also able to guess how to switch into graphic mode, so in theory I was able to print images for some time. Unfortunately any CUPS drivers I used did not provide acceptable results, so all I could do was to write some support tool myself. Continue reading “Printing pictures like its 1873 using Oki 3321 dot-matrix printer”→
When I have seen CO2 sensor for the first time, it was quite expensive device. Well, if one want to buy consumer device these days, it still could cost a lot. However in the days of cheap Chinese electronics sellers on biggest auction platforms, for makers, situation is quite different now. MH-Z14 is the cheapest CO2 sensor I was able to find. I costs about $19 and comes in few variants: MH-Z14 and MH-Z14A. Also it can measure up to 1000 ppm, up to 2000 ppm or up to 5000 ppm. However the range does not matter in practice, as it is possible to switch between them using UART.
The device interfaces are quite flexible for such a cheap device, as beside mentioned UART port it provides PWM and analog output. However, I was not able to measure valid value using analog and my cheap multimeter. Maybe some more sophisticated equipment is required for that.
While tinkering with spy camera, I found one detail that is significantly slowing the process of reverse engineering and debugging the applications, installed on its embedded Linux platform – finding final values of preprocessor directives and sometimes also results of sizeof() operator.
As I am not aware of any existing solution for that problem (I guess there might be some included in one of the more sophisticated IDEs, however I use Vim for development) it is good reason to create one. By the way I used cmake template I published some days ago to bootstrap the project. Continue reading “SADVE – tiny program for computing #define values”→
First of all, we need kernel. To be precise, kernel sources. Without that, it is really hard to be successful (I don’t want to tell it is impossible, but really hard, believe me). Because Sony is very liberal in terms of cooperation with community, they provide anything required to tinker with the device (obviously together with caution message about warranty loss, but who cares, right? 🙂 ).
Lately, I bought some random, noname spy camera from usual Chinese sources. Just after unboxing, one detail seemed a bit suspicious to me: together with the camera there comes a link to Android app, that is meant to control the camera. What is worse, the link leads to some Chinese app shop, obviously with only one language available (notice the version – 1.0.33, as it is not the only one in the wild):
As I’ve already seen apps that i.e. calls home, despite having no need to open a single socket and then sending data like IMEI, IMSI, MAC addresses and so on, red lamp turned on and I said to myself: stop. Let’s reverse engineer the thing first!
Before I begun my reverse engineering, I attempted to ask uncle Google (and his friends 🙂 ) to gain some knowledge. Usual virustotal gives me this:
Few weeks ago I made an attempt to reverse engineer some obscure Android APK. It was available only through some Chinese shop, obviously described in only one language there. Unfortunately, it turned out that every tool designed for reverse engineering APK files outputted source with mysterious resource IDs, as plain integers, which is not the most convenient way to read them. Therefore I started looking for any way to find some meaningful name from these ids. At the end of my development effort I found out, there is one file that usually might be used for that purpose – res/values/public.xml, as produced by apktool (if I remember correctly). However, according to its name it contains only public resources, so some of them are missing there (in my case at least some drawable type resources were missing). Therefore, I am publishing my program to do things even more reliably.
This program requires my library created together, but which is separate project – libarsc. It is available, as usually through Github and also as a package to be downloaded from PyPI. Just type: