05

ELECTRONICS DESIGN

Disclaimer: I learnt after making the PCB that the ATTiny44 is an outdated microcontroller that is no longer used for reasons I don't understand. I would've been better of attempting the 412 or the 1624 (if I wanted to stick to the ATtiny world) apparently.

Schematic Design

The assignment was to go a step forward from the exercise in Week 3 to redesign an echo hello-world board and add a button and an LED. Despite being largely oblivious to the workings of a PCB, I ventured forth to attempt redesigning the ATtiny44 echo board. In the process, I referred to this previous project, especially the websites referenced within the documentation. I also found this page very useful because of the images showing the various parts and their labels--it made finding them in the shop much easier. I used Eagle to first redraw the schematic of the original board (image on the left) and then added a switch and an LED to the schematic (image on the right). I am yet to understand what is happening on the board and what the role of each component/connection is.

Board Design

Untangling the board parts was proving to be very difficult. I depended heavily on the placements in the original board (image on the left) and the reference sites to optimise the position of the footprints to eventually allow for easier routing. DRC (design rule check) was a very helpful command both in the checking for errors as well as to set the signal widths/clearances. In the process of routing, I started exploring the potential of shaping the circuit board like a rocket. I'm pretty happy with the resulting traces (image on the right) and the use of the 1x6 FTDI-SMD-HEADER as the rocket's exhaust.

Milling and Stuffing

After processing the traces and outlines on Photoshop, I used Roland SRM-20 to mill the board. I would have preferred the traces to be a little thicker (with correspondingly greater clearance) to give me more room for soldering.

Testing

Sadly, I was not able flash my PCB because the ATtiny44 is not really used anymore and I could not find the necessary support (people/instructions) to test it. It was however identified by the USB slot (see image). I'd like to think the PCB could have worked (with a blinking LED on the rocket's head) if it could have been bootloaded and programmed.