Category Archives: QWT

Qt Embedded 4.6.0 + Qwt + kxps5 accelerometer!

After testing the operation of the kxps5 accelerometer with i2c-tools i wrote a test application using the i2c-dev interface. If you want to test your code before you write a kernel driver this is definately a good place to start. Once i had the configuration registers set properly and i had a routine for reading the acceleration vectors I stripped down a ds1621 kernel driver to a bare minimum, and then built it back up again to work with the kxps5. I then bitbaked the kxps5 driver as a kernel module, along with hwmon and it works perfectly! 🙂 Next i cross compiled qwt 5.2.0 and plotted the acceleration as function of time. The video below is taken with antialiased lines which slows down the refresh rate but makes them look nice. If you plot it without this enabled it runs very smoothly. Here you see the kxps5 running without an external low pass filter (the internal filter is 1kHz) and despite this the output is pretty stable. What impressed me the most is the sensitivity. When placed on a desk the free fall interrupt indicator lights up if you drop one of the little nuts from the friendlyarm LCD about 10cm away from the device!

Watch this video on YouTube.

The kernel driver for this is now available here.