May 052011
LCD and Arduino

Driving a LCD from an Arduino is no problem at all. There are nice libraries doing this. I bought a slightly different display which uses an I2C interface instead of the usual 4 or 8 bit parallel interface. Since I connected recently the Wii Nunchuck which uses I2C too to my small Arduino board, the next logical step was to add the display too. After all, I2C is all about adding devices to a 2 wire bus.

There was only one small problem: I2C LCD is not supported natively by the Arduino library system. But someone (and I really do not know who as the amount of comments was limited) created a library for Arduino here. All I can say about the author is that he (or she) is using a Mac and probably Japanese since I found a Japanese comment. This library was a great starting point, and although it was not complete and quite some functions were commented out with a “Does not work”, they worked out fine after I replaced them with what I thought should be here according to the data sheet of the used controller (ST7032i).

Now I have connected to my Arduino:

  1. Wii Nunchuck (2 button, 3 axis accelerometer, analog joystick)
  2. LCD (2 lines with 16 characters each)
  3. Servos (like those)
  4. A 12V fan which can be controlled via PWM to change its rpm
  5. LEDs of course
  6. 12V relays

If anyone wonders what the goal here is, for those I can only say: “Der Weg ist das Ziel” by Confucius.

Next on my list:

  1. RTC via I2C so the Arduino knows what time it is
  2. A piezo buzzer
  3. More sensors, like temperature, humidity, light etc.
  4. Another uController via I2C

With the first two I can make an alarm clock. Not that I would need one…


May 032011
Kubuntu 11.04

I upgraded my notebook from Kubuntu 10.10, which worked well with only few (but annoying) issues. One was that once in a while the internal NIC will behave funny: either it won’t connect at all, or only 100 or 10 MBit/s instead of GBit/s. The fix is to power the notebook off, remove the battery, wait few seconds, then put back battery and power.

The other problem is that if you tax the CPU too much (think: compiling Linux kernel using “make -j” to keep all CPUs busy), it’ll actually shut down as the CPU gets too hot. The price you pay for having a too powerful CPU in a notebook.

So I thought, since 11.04 is out, let me try that.

Well…the good news is that nothing important broke.

The bad news news is that small things broke:

  • Firefox (now 4 instead of 3) knows no Adobe Flash anymore. However Google Chrome does. Odd, but works for me.
  • The CPU fan started and kept on running at full speed.  See bug report here. The highly in-elegant fix is to limit the CPU speed severely.
  • /proc/acpi/thermal_zone no longer exists. That is now using the /sys interface and it’s in /sys/class/thermal/thermal_zone*/. Some tools still use /proc only, which makes them display no temperature anymore, although the kernel knows the temperature.


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