This week started with watching many tutorials on the use of eagle, and researching all about electronics design. Aside from my positive experience creating a circuit board during week 3, I am a neophyte, so I have had to start at square one, beginning with the basics, like learning the symbols on schematics.
Components:
I was sick last week, so was unable to attend the CBA recitations until Monday, but luckily, Thrasyvoulos Karydis the CBS TA for this week's subject was very helpful in providing me with support, he gave me information to start my explorations in this week's subject.
I began by downloading Eagle, which, like Fusion 360, is part of the Autodesk suite. As a student I have been able to access these powerful programs to assist with different aspects of this course. I had to locate the correct inventory libraries to begin working with the components. Two relevant libraries were already available with eagle: 01_FAB_Hello and 01_ng, both of which had some of the necessary components. I searched within the class website to find the fab.lbr library, downloaded it as a text file and was able to upload it to my local eagle file, making all the components readily available. I began by looking up and listing each component as listed on the hello.ftdi.44 board image.
1x ICT1t44: AT tiny 44A-SSU, Integrated circuit with many uses
1x R1 10K: Resistor, provides limit to current
1x C1 1uF: Non polarized capacitor, provides a buildup of charge
1x J1 ISP: 2x3 pin ISP header, For connecting to the programmer
1x XTAL1 20Mhz: Crystal 20 MHz, For keeping time
1x J2 FTDI: 1x6 pin header SMD, Connects the board to power and the computer
In addition, I added the following components required for this assignment:
1x LED 1206 SMD, a tiny red light
1x Switch tactile SPST 0.05A 24V, tiny button will provide board an "Off Mode"
1x R1 10K, For providing resistance to limit the current flowing through the LED
I built several schematics by adding components and connecting them together. Thras suggested connecting the components by naming them, and he showed me how to do this. I noticed several other students had success with this. I tried it and lost track of the connections, so I chose to continue to use the net tool to connect them visually for this exercise. I started over several times, to ensure I had selected the correct components from the library, made the right connections, and oriented them correctly. When it was time to move from schematic mode to board mode, I struggled significantly with creating problematic traces. It took me several tries to locate the components and connections successfully. At first, the traces crossed over each other, I had to tell the program to draw the traces on one layer only. Then, the program placed the traces going through areas where there was not enough space for them. I decided to relocate the button and LED light, which gave the traces more options for space. When I finished the board, I realized the lines were too small, and decided to make them bigger to make sure the current can flow successfully. I had to move some of the traces over to make room for the bigger lines. I ran the design rules function and it identified a couple problem areas for me to fix. I used the ripup tool to make the changes and all seemed well. On the bottom layer, I drew the exterior line, and exported both the top and bottom layers as .png image files for milling.
I went to the CBA lab first to use the modelo there, since I had luck with it previously.
Unfortunately, it was not working correctly, the View Mode light kept flashing even when I tried to clear the buffer, close and re-open mods, reboot the computer, and reboot the milling machine itself. Luckily, John was in the lab and he worked on the problem while I went down to the electronics lab to use the miller there.
I had no problem with activating the milling process. I did have one issue where I miscalculated the origin point, causing the design to be printed right up to the edge of the traces.
Luckily, the traces were on the board, but I had to rework the outline to three lines so that I wouldn't break the bit. It worked well. Part of the copper trace wire between the capacitor and the ATtiny were too close and the milling machine did not separate them.
I had to edit the board with a cutting blade, making sure to cut deep enough so it would not create a short.
With a successfully printed board, I began to solder on the parts.
Soldering went well, including placement of the LED, which must be placed with the cathode line facing the direction the current is flowing.
After each component was tacked on, I tested each with the multimeter and each worked. I connected the board to the programmer and 6 pin USB cable to the computer.
When it comes to making things, I am always interested in the accessibility of materials. Are they readily available, easy to use, or could be used by a layman? Are they flexible – can they be used in a variety of ways for a variety of purposes? This is one reason I like clay so much: you can do so much with it, and it's easy to obtain. On this topic, when I was shopping for gifts for my kids a few months ago, I came across a pen with conductive ink that kids (or anyone) can use to make circuits. I saw it at the time and was curious about it, but didn't buy it.
Given the difficulty I had with the modelo both times I created circuit boards, I thought this time I might try to make a successful board using the pen with circuit ink. The pen came packaged in a kids' kit with a bunch of different parts for about $45. I did some research on the pen and it turns out the company recently did a kickstarted campaign to help the "Circuit Scribe" kits reach the market. They are currently working on industrial uses and had posted a tutorial on how to use the pen to make circuit boards with real parts.
I printed the image of my "LEDbuttonboard" onto glossy photo paper in order to maintain good insulation for the circuit. I used a piece of mat board underneath for a hard substrate. Then, I drew over the traces with the pen. The pen poses many issues that limit accuracy.
It's a ballpoint pen and the gauge is thicker than some of my traces. I had to very carefully go over the lines to make sure they had enough space in between them, and it took several tries. I'm still not sure if it will work. Also, the ink does not flow consistently, so I would have to stop and try to get the ink flowing again. It also collects on the tip of the pen so it has to be cleaned frequently.
I think the pen needs to be further refined in order to be truly useful. Still, it's technically a child's toy, so it doesn't need to be very accurate. Next, I glued the components onto the board with superglue, as the tutorial suggested.
We shall see if the superglue will allow for the current to flow adequately. If the finished board works, I think it would be a good option for making this kind of work accessible to more people. It's exciting to think about possibilities for making objects where all you have to do to create a circuit is draw it.
I created a new design in my third try. It was successful! What was wrong initially? Debugging revealed: I was using a resonator instead of a crystal. My circuit traces were too thin.
The computer was successfully talking to the board! I got it to do so in the Ubuntu terminal following the code and was able to successfully burn the bootloader in Arduino.