07. Electronics design

Electronics Design

This week’s assignment was to redraw the echo hello-world board using Eagle and then fabricate it.

you can find the my folder here to download

hello world schematic

from my background of architecture i needed to review the electronics from scratch
. and here is some of my noted i take during our electronics revision 8

three main things i need to consider while designing electronics :

  1. add components to the schematic view and then create correct connections between them.
  2. check and verify the design using the ERC (Electrical Rules Check).
  3. finishing the connection of components and fix any rapid errors -switch to board view and place the components and route the traces.

three main components meanings:

CURRENT is the directed flow of charge through a conductor.
VOLTAGE is the force that generates the current.
RESISTANCE is an opposition to current that is provided by a material, component, or circuit.

it was a bit scary to open eagle at this time but here we go 8

and here are the two main windows we are going to use to build up the board.

Schematic (.sch) - logical components

Board Layout (.brd) for the actual board that we mill

and we can switch between them using this button

as directed by the tutorial i needed to download the fab library of examples. so i downloaded it from this repository and copied paste it the folder inside the library folder inside the program. what’s next is to open a new project by right click on projects and then open the schematic view 8

to use library i added i will go to library and library manager and then browse from the library location on Eagle program files


this is the board that i will redesign so starting with

and then we need to start adding component accordingly to the board.

  1. add button
  2. add grounds
  3. add VCC
  4. add LED
  5. add resistor

there is an important note to consider: knowing the function of the board is an essential part of designing electronics boards after that we can look at the data sheet for the microcontroller.

Datasheet for my microcontroller i found it here: http://ww1.microchip.com/downloads/en/devicedoc/Atmel-7701_Automotive-Microcontrollers-ATtiny24-44-84_Datasheet.pdf

Datasheet includes very useful information about architecture of this device. The most useful information for current step is pins configurations:

after adding the components i wanted to add VCC and GND .

As per the original echo hello-world ATtiny44 board and using “Net” tool, add wiring to components. wan to make sure to draw direct connections between components when it’s possible!

Switching to the pcb designs :

Fine yellow wirings represent the connections made in the schematic. All those wirings should be replaced using “Route Airwire” tool. from this repository as (fabcity-designrules.dru) copy paste to “..\Documents\EAGLE\design rules”.

In Board Editor go to “Tools > DRC…” and then select “File” tab. Click on “Load” and locate fabcity-designrules.dru on your drive. Click “Open” and then “Apply”. The DRC window title is changes to DRC (fabcity-designrules). Click “Select” to close the DRC window.

Last update: November 30, 2021