Sorry for ranting, you do not need to read this. I hope writing this down helps me sleep.
There’s this new virus Covid-19 (formerly known as 2019-nCov), that is rapidly spreading. It will not be the end of humankind, there have been much worse pandemics in history, but it *will* kill and it *will* change our world.
- Mortality is around 1% (averaged over all age groups) *if and only if* you have access to intensive care units.
- Mortality increases to 3-5% if no intensive care is available
Our old dreambox 7000 records movies in the mpeg-ts format (file extension:.ts). I wrote a Makefile to burn recorded files to dvd.
The old version of readesm was using a command-line interface to convert the tachograph data into html. If one wanted it shown in the browser, there was a script to convert the file, write it to a temporary directory, and then open that file in the browser. However, this approach turned out to be not portable at all.
There were other problems: readesm was using custom Makefiles, which apparently made compiling the source difficult. I was amazed to discover this wiki entry for fahrlinx, which contained information on how to install the windows version of readesm using wine. As the windows version at that time was cross-compiled in linux and lacked some features, readesm was clearly too difficult to compile.
Digital tachographs are a compulsory equipment for heavy trucks in the european union. The companies owning these trucks have to download the data at least once every 3 months.
Without dedicated hardware, this was so far not easily possible in linux, but my python script should make it possible to download the data with a serial cable with the right connector.
In some cases it is convenient to have a shortcut to open the newest file in a directory. Maybe the last show your dvr recorded, or the last file you bought from amazon.
For these cases I found this little bash snippet useful:
ls -tr | tail -n 1 | xargs -I FILE kde-open "FILE"
Posted in Computers
Tagged bash, snippet
This article describes building a small (3.3 cm times 3.3 cm) RC servo controller using an avr microprocessor and an FT232RL USB-uart chip. All RC servo signals can be set to pulsewidths from 0 to 8.1 ms using the usb-serial interface.
RC Servos are popular among modelling and robotics enthusiasts because of their simplicity. They take a pulsewidth-encoded input, and turn accordingly with relatively high torque. They have their disadvantages, for example one cannot tell if the servo was able to get where it was sent, but their low price and the fact that driver and gear box are integrated make up for that. Also, Conrad sells them for 3 € a piece, so I bought some.
Posted in Electronics
Tagged avr, servo, usb
Due to my slightly outdated computer flash is a huge problem. So, for viewing youtube videos, youtube-dl.py is a great solution. However, I wanted something more comfortable.
ytplay wraps around youtube-dl.py, it searches for a video, orders youtube-dl to get it, and starts playing it in vlc.
Usage is simple:
> ytplay foobar
will search youtube for videos about foobar and play the first one found.
The code is still quite dirty, especially the subprocess part. However, it should work, have fun!
Having recently acquired a bluetooth GPS receiver for as little as 20 €, and just having switched to KDE 4, i tried to combine those two, and write a little plasmoid to show the current position on the desktop.
And that is basically everything to say, enjoy the little applet.
LCD Controllers using an HD44780 Display Controller are commonly used for small batch electronic devices, and are popular with electronics fans worldwide. One problem with those controllers is their demand for IO-lines, due too the parallel interface they require at least 7 IO lines.
One solution, if you don’t have enough IO ports to spare, is to use another Display, like serial cellphone displays, which are cheap and color is a great thing to show off. Or you can expand the number of IO lines by using a shift register or TWI device. This is one such implementation using a 74hc164 shift register. It is based on an implementation by Peter Dannegger. If you prefer to use a 4094 cmos shift register, there are also schematics floating around the net.
Posted in Electronics
Tagged avr, c++, lcd
Update, November 2011: See the post about readesm 2011 and the sourceforge project page for newer descriptions of readesm.
Update, March 2011: There is a new release of readesm, The description provided here no longer applies, the new readesm uses Qt and cmake. You can get the new release at the sourceforge project page and read the documentation here.
For several years now, new trucks sold in the European union are equipped with digital tachographs, that record the driving times and replace the older chart-based mechanical tachographs.