Week 6 - Electronics design

Assignment

Redraw the echo hello-world board and add (at least) a button and LED (with current-limiting resistor)

Check the design rules, and make it

Redraw the echo hello-world board

For this assignment we are going to start working with EAGLE (my first time), and the first thing to do is downloading the EAGLE software here

The second thing to do is start watching some tutorial here, there is also an assignment tutorial, cool! here

Working whit Eagle

Once we have installed the software we must download the fab.lbr file (fab library) and drop it into the libraries folder of Eagle /Eagle/lbr. To activate the libraries launch Eagle software and go to libraries/use.

Now we can start a new project. File/new/project, and then we must create a "new schematic"

List of componennts:

1X 6-pin programming header

1X Microcontroller: attiny44A

1X FTDI header

1X 20MHz resonator

2X Resistor (value 10k)

1X Button

1X LED

1X Resistor (value 100 ohm)

Now we can start adding components by clicking in toll button of the side bar, selecting them fron de fab library

It's important to set the connexion betwen the components by clicking in the "name" button, set it's values whit the "value" button and connecting with the "Net" button.

It's also important to set the DRC clearence settings as you can see in the image. This value corresponds to the tool diameter 1/16 and thus we guarantee that we will be able to pass everywhere when we do the tracess.

This is the scheme of the board

At BOM we found some components like 'resistors', how is it? how does it works. The resistor included at BOM is enough to let the LED bright in a consistent way, he larger the resistance value will emit less light the LED.

Here a online resistance calculator

Back to Eagle, now we can change of window by clicking in the button "Generate/switch to board" in the top bar

At this point we see the components linked through fine lines, these lines tell us which points are joined together. The first thing is to drag the components inside the window of the workspace

Now we can change of window by clicking in the button "Generate/switch to board" in the top bar, At this point we see the components linked through fine lines, these lines tell us which points are joined together. The first thing is to drag the components inside the window of the workspace

It is now when we begin to add the "Route" lines (use "wire" button) that join the different components, trying to keep it in an orderly manner and that the lines do not cross each other.

Once the position of the lines and components has been edited, trying to make it looks like the design we are reproducing, we generate an image based on the design, this image will be use to make the milling

Before creating the png image we must turn off some levels, by clicking in the top bar "View/Layer Settings" and selecting the levels we want to turn off and then click on "Apply"

Now we have the lines and the pads but still visible some little text. To turn off this text click on the top bar "Options/Settings/"and click on "Misc" tab and diselect the options that displays those texts.

We are ready to "File/Export/Image". Select the folder where you want to save the png image, slect the "monochrome" option, set the resolution to 600dpi and the option or area by "window", and the "OK". It's better if you rezise the window of the Eagle application like in the picture above

This is the result of distribution of the different components always trying to optimize the dimension of the board.To obtain the "outline" png file I used Gimp, It is important to check that the dpi stills on 600.

Milling

Check the week 04 - Electronics production Assignment, there you can find the information about how to mill a PCB Board.

In Fabmodules set the parameters for traces, calculate, save the rml file. the same for outline file.

Place the board to mill on the monofab bed surface.

In VPanel. Define the X,Y and Z origin, place the tool , click on "Cut" button and then load the rml file, then click on "Output". After milling clean the board.

This is the result of the milling, I had to clean a little the board using a cutter, i don want to have problems with the conexions after the soldering.

Nice result, but...., as you see there is an error, there is a pad and a trace together. I cut it usin a cutter. it'´my second milling in FA.

To know how to perform the milling check the information of the week 4 Electronic production

Soldering

An importat equipement, the 'Multimeter', When i'm in soldering process is very useful to check the connectivity.

A digital multimeter (DMM) is a test tool used to measure two or more electrical values—principally voltage (volts), current (amps) and resistance (ohms). It is a standard diagnostic tool for technicians in the electrical/electronic industries.

The terms counts and digits are used to describe a digital multimeter’s resolution—how fine a measurement a meter can make. By knowing a multimeter’s resolution, a technician can determine if it is possible to see a small change in a measured signal.

Example: If a multimeter offers a resolution of 1 mV on the 4 V range, it is possible to see a change of 1 mV (1/1000th of a volt) while reading 1V.

To know how to perform the soldering check the information of the week 4 Electronic production