Since the last blog entry I’ve done two main things for the project:

  • Update the software to make it a bit cleaner
  • Created a PCB design for fabrication

Software Updates

There’s not that much to be said about the software updates. I’ve cleaned up the code and finally figured out how to split it over several files without a huge number of compilation errors! As far as I can tell, the code appears to be working the same as before, and it should be easier to maintain in the future.

As always the latest version of the code has been uploaded to the Google Code project page at …

PCB Design

This is the more interesting part of this version update.

After a good number of weeks, I finally have a PCB design that I’m happy with. Below are some of the issues I’ve been having with creating the design.

  • Making everything small enough so that it can fit on a finger design, and most of the components will fit under the screen;
  • Some of the components weren’t available on Eagle Cad (which I used for creating the PCB), so I had to learn how to create new library components;
  • It’s been a long time since I did any PCB design work, so it took a while to remember some of the basics of PCB design.

But after a few weeks of work, I finally have something which I think will be useful. The figure below shows the PCB design which I’ve come up with. As cn be seen, almost all of the components are under the OLED display, but since I’ve never actually built a circuit with so many SMD components, I think the circuit might be more difficult to make then it looks (to me).


The large square in the middle (with the pins at the top) is the 0.96inch OLED display, which should give a good indication of the overall size. The three buttons of the right are Up, Down, and Off / Back. You can’t see the Select button because I think I’ll need to make this separate with wires to make sure it fits on the side of the finger.

The PCB is double-sided and has been sent to ITead Studio for fabrication. If all goes well, I should have a working prototype within the next month or so, so fingers crossed all goes well.