Monthly Archives: January 2015

USBasp USB-Programmer Firmware update

2015-01-25Arduino, ATtiny, Programming

I recently purchased a cheap USBasp clone (Made in China), originally developed by Thomas Fischl. It is an USB in-circuit programmer for Atmel AVR controllers. It simply consists of an ATMega88 or ATMega8 and a couple of passive components. The programmer uses a firmware-only USB driver, no special USB controller is needed.

No driver is needed under Linux in order to program Amtel chips. With the Arduino IDE, it is enough to connect +5V, GND, MISO, MOSI, SCK and RESET to the respective pins of the microcontroller. However, after uploading a sketch, avrdude complained about an outdated firmware version:

avrdude: warning: cannot set sck period. please check for usbasp firmware update

So I decided to attempt to update the firmware on the USBasp using one of my Arduino UNO boards as the programmer. There is a lot of confusing information on the web about how to do this, so here is what worked for me:

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How to plot the frequency of PIR sensor events?

2015-01-04GNUPlot, MySQL, Raspberry Pi, SensorsGNUPlot, MySQL

With a PIR sensor one can detect movements within it’s field of view and trigger other hardware, such as surveillance cameras. It is also possible to record the frequency of movements over time, e.g. to monitor motion activity in a room of your apartment.

With a PIR sensor attached to my RasPi, I recorded motion events by storing UNIX timestamps in a single-column MySQL table. I wanted to visuaize these data points as a histogram displaying the frequency of motion events over time, but this task turned out to be more complicated than expected using GNUPlot. So here’s a short tutorial how it works: