Suppose you have an old joystick that you want to use to control your latest micro-controller project. These joysticks use a DB-15 connector with a readily available pinout. A Game Port style joystick consists of digital buttons, and analog axes. In this post, I will go over how to optimally interface the axes of these types of joysticks with your microcontroller. Inside of the joystick, mounted at right angles are potentiometers, one for each axis: Read more...

I recently took a class on Embedded systems design at PSU. In this class, we covered designing memory systems, serial busses, as well as sensors, transducers, and outputs. The labs for this class used an ARM development board based on the (then Intel) PXA270 microprocessor. Students were supposed to develop software in ARM assembly to demonstrate what was learned in class. I decided to implement my solutions in C to provide more of a challenge. Read more...

Recently I took a class on Embedded Systems at Portand State University, and was required to program a bare metal ARM development board. This is a continuation of my notes on how to program the board. You can read the first part here. In order for this development environment to work, we need to implement the syscalls that newlib will use for the C standard library. Most of the required syscalls are necessary in order to access abstractions that wont make sense on the development board. Read more...

Recently, I participated in Oregon State University’s Engineering Expo. Every year, freshmen are encouraged to enter innovative designs based on the TekBot learning platform used in the ECE program. A friend and I decided that we would try to implement a macro system for the robot: by using an NES controller, we could have the robot record button combinations and sequences, then play them back later. Boy did we learn a lesson about procrastination. Read more...