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Electronics design

Week 6

Make Schematic

This week's work was to design, fabricate and program the echo hello-world board by adding some extra components like a button and an LED.

I used the Eagle program to do the schematic and then get the design of the electronic circuit on the pcb with the paths between the components.

To make echo hello-world you will need the following components:

  • Attyny 44
  • 1uf capacitor
  • Ceramic resonator
  • Pins header
  • FTDI pins

  • Extra componentes:

  • Switch Button
  • LED
  • * Each type of LED requires a different resistance depending on the value of your voltage. On this site can help you to calculate the resistance that you will have to use:LED Res Calculator

    These components can be found in the library: fab.lbr

    Work with EAGLE

    Make Schematic

    Eagle is a software for PCB design that works easily and with easy-to-use tools for every engineer.

    Components should be placed in the circuit correctly. Just like the example in the figure.

    Eagle is free autodesk software and you can find more information here:Eagle software

    The eagle is an easy program to learn. To make an electronic card You should start with drawing and drawing the diagram.

    For this we must first put in the eagle all the components that we want to put on our electronic board.

    In the command bar there is a command that is "ADD" that opens a window with several components that you can choose.

    Besides these components that comes with Eagle you can inatalar some libraries with more componenets. FabAcademy has some libraries to download, which are:

  • fab.lbr

  • After the added components you must create the routes between them and connect them correctly. It is necessary that you have some experience and notions of electronics to do it correctly.

    In the Eagle toolbar, you have basic commands to select, move, copy, paste, etc that you can use.

    And you also have commands to draw the routes between the components that are the green and blue symbols. In addition you can draw shapes like rectangles, circles, etc ...

    To not fill your layout with many routes because it will be confusing, you can use the Label command that is the one that has a green line with an "AB" and make a label to your component, which will join a component with the same name.

    For example, labeling an output pin of the microcontroller with "TX" and labeling a component pin with "TX" will make that although you do not see, they are connected.

    Your components should be labeled to better understand positioning on the board.

    For this you can change the "properties" of each component by clicking with the right side of the mouse. With this it is possible to define the value of each component, this can be useful for example to define the value of the resistors.

    The following diagram represents the final drawing of my board.


    Once you have the schematic well defined, you can click the "switch to board" icon on the eagle's top toolbar and the program automatically generates the components on a board and some yellow lines that are the driving lines between the components . As we can see in the figure.

    Before proceeding to the next step of drawing the driving lines between the components, you must go to the "edit" menu and click on "net classes" to define the thickness of your lines, which should be 0,4mm

    From there you can draw the circuit based on the yellow lines of the circuit.

    To facilitate there is a tool that draws automatic lines.

    I used this tool at first and I was changing my drawing until I got a correct 100% complete layout. This is a process that takes some time.

    After having my board made, I exported the image from Eagle, and I used the illustrator program to extract the vector lines from the image of the board.

    For this, I just click on "living trace" button and then make some adjustments to the lines drawing.

    When the board design was finished, I save the file in svg format ready to go to the milling machine.

    Milling and Soldering

    After I got my drawing ready from the board, I put it in the milling machine to get my board with the copper lines, just like it was done in week 4.

    After that, I did an illustrative scheme of my board based on my schematic, to better understand the positioning of the components and started to solder.

    My pcb is ready!

    Now it is necessary to program and see if we can click the button to turn on the light.

    These are my two Hello-world boards.

    STEP 2


    After realizing how electronic board manufacturing works, I decided to make a microcontroller board, like an arduino, for my final project.

    On my microcontroller I added:

  • Attiny 44
  • 3 leds with different color, with 1 resistance each
  • ISP pins to program
  • 1 digital pin output
  • 2 analog pins output
  • 2 output pins - GND and VCC, for connecting a battery
  • 1 FTDI pins for connection to the computer, and with a future wifi-module

  • I programmed my board easily.

    In week 8 you can see how it was.

  • week 8. Embedded programming


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