Home | Weekly assignments | Final project

week6

*assignment

-group project:

-use the test equipment in your lab to observe the operation
of a microcontroller circuit board

-individual project:

-redraw the echo hello-world board,
add (at least) a button and LED (with current-limiting resistor)
check the design rules, make it, and test it

extra credit: simulate its operation
extra credit: render it

Test equipment(Digital Voltmeter and Oscilloscope)

Digital Voltmeter

At first we used digital voltmeter to check connection.

Our body has 1.20ohm resister.

Oscilloscope

And then we tried to test with Oscilloscope.
We can check frequency, noise, and amplitude over time with it.

We put probe tip on circuit board.
And used breadboard and external wire because of protection for the board.

1.Making PCB software:Eagle

I chose to use Eagle as software for making PCB.
My instructor Rodrigo recommended us to use Eagle.
I've never made PCB before so I just accepted his advice.
guide

And also there is a tutorials on Fabacademy.
It's really helpful.
If you're beginner, I highly recommed you to read and read tutorials.

What is Eagle?

EAGLE is abbreviation of (Easily Applicable Graphical Layout Editor).
We can use it freely.
So that's why many people already use it.
And there are so many component libraries which we can use and refer.
You can download Eagle Here.

2.Getting used to use Eagle

search

First, I just followed tutorials
I downloaded fab.lbr
And put it in the Eagle folder and changed name "00fab".
Because searching libraries on the Eagle, they are listed in alphabetical order.
So as to search easily, we should changed fab.lbr to "00fab".

search search

On the seach bar, putting the parts that you want, we can see and find.
But some problem happend.
When I searched 'LED', no problem.
But with 'attiny', it didn't show anything.
And that time I found explanation on the right.
It guided me to add "*" in the last.

search

I tried with "*".
And then succeeded.

3.Redrawing 'the echo hello-world board'

echo

Comparing to this image, I added the parts needed.
the parts: Attiny44>Attiny44-SSU / AVRISP>AVRISPSMD / Cap-unpolarized>Cap-unpolarized C1206 / FTDI-SMD-header / Res-US>Res-US1206Fab / Resonator
redraw

I redrawed 'Hello echo world' and added 'LED' and 'Button' on schematic.

redraw

On the board, it appeared like above.
And then 'autorauter' function helped me to draw line.
I had to export this image into png.

redraw redraw

In layers, except 'top' none should be selected.
And 'Monochrome' is so important.
Because it is related to 'black and white'

I opened this png file on fabmodule site.
And I calculated this image to see how it would be miled.
I found something wrong happend.

redraw

Some parts are connected even though they were not on png file.
So I should deal with it.
First I tried with 'Inkscape.'
And I got into unexpectable error.

redraw

The size is different!!!!!!
So all my efforts were gone.
I was so sad.... and should start from the bottle.

redraw
I tried with 'paint'.
Still some error happened.
I don't know why but in the process of exporting png file, the size would be changed.
So I didn't use.
Because of using it, outline size would not match.

redraw

Finally, I used with 'Gimp'.
And then there was no problem.
Size Ok, Picture quality Ok.
I drawed line by myself.

redraw

Now that I got right image.
I could mile.

mil redraw

I got milled one. But I found something really wrong.
All the componants that were originally supposed to be with the same size are totally different and so small.
(You can see this on the right picture.)
This is because I editted all components one by one on 'Gimp' , using eraser and pen tool.
This is totally wrong and I found I should restart again from the bottle and draw by myself, not 'autorauter'.

redraw

I redrawed one by one. and finally made it.
And also I found the cause of my problem.(connected and extraordinary smaller on fabmodules than I thought)
This was not because of 'autorauter'

The reason of problem

This is related to DRC.
Before showing how to solve problem.
I'll explain 'ERC' and 'DRC'.

ERC

ERC(Electrical Rule Check) is a powerful tool to help us check important things.(Schematic on Eagle)
It checks when the components and lines are connected or not.
(Sometimes when zoomed out, it looks like connected though it's not actually) And also electrical things can be checked.
For example, I drawed line from output to output.
It's wrong and we should be careful for our safety.
But on the schematic it doesn't show any problem.
So ERC functions this time.

erc

Click here. ERC emoticon.
erc

And then automatically checked and show you.

DRC

DRC(Design Rule Check) is a series of tests to discover logical and physical errors in the design.(Board on Eagle).
It fuctions quite similar to ERC.
I found the good explanation about DRC on Sparkfun.

I searched 'drc' on Sparkfun.
There are many referenecs.

drc ex

Drc explanation from 'how to use' to 'fuction'.
Read before using DRC, it will help you a lot!

drc ex

Here is the fuction part.
Most of the functions are about Design.
For example if the lines are overlapped, it means connected though they are not supposed to be.
Drc can find it.

redraw

I checked 'ERC' on schematic and 'DRC' on board.
It has no problem.
But this was really important but I ignored.

redraw

I didn't care about drc clearance on previous one.
So the problem happend.(many lines and components were connected.)

redraw

I put this png file into fabmodules. and then got the right caculated milled board.
Still some parts were connected, but it was understandable.
I just moved some lines to avoid connected.
And then solved.(right picture).

4.Milling and soldering

Now that I got ready for everything to start milling, so I did.
First try, I failed to get the right one.
I did set wrong z value, so it didn't cut well(not deep enough).- right picture
So I resetted z value and then got the right one.- left picture

redraw

I soldered and felt better than first.
At my first trial, I had spent almost 3 hours to do this.
This time, only a little over 1 hour took.
But problem happended, my soldering was so ugly and during re-soldering some parts, I broke my board again.
So I repeated milling and soldering.
(This week was so amazing for me.... All failures were coming to me....hhhh)

redraw

I tried again.
And this time was much better than before.
As I already had failed a lot, so I was afraid of running into fail again.
So I asked Rodrigo(my instructor) before programming whether this board is okay or not for programming.
And he answered me my soldering was quite ugly, which can lead to fail.
I didn't know the conception.(ugly soldering can fail)
So I did again and got the above one.

5.Programming

I followed this link highlowtech.org that was very good for downloading the Attiny board for the Arduino.

I just followed the guide line and got it.

I wanna give myself a hand to go through so mannnnnnnnny failures and finally got it.
This week was amazing.... I will never forget.
Anyway thanks!

downloads

untitled1.sch
untitled1.brd
minsoo 3.png
minsoo 3.rml
minsoo 3 outline.png
minsoo 3 outline.rml