---
tags: Fabacademy
---
# Week06 - Electronic design

### For simulation
We do not cover the subject but in Kicad website there is all the info to do it.

## Concept

## Design

### Import library
Download library from https://gitlab.fabcloud.org/pub/libraries/electronics/-/tree/master/kicad
#### Symbol
Installing the library
Preferences -> Libraries -> Manage symbol library
Create new empty global library

Repeat possibly with (optional) : https://github.com/KiCad/kicad-footprints
#### Footprint
Preferences -> Libraries -> Manage footprint library
Add an existing library, select fab.pretty

### Schematic edition
Keystrock
* M = move
* R = rotate
* E = edit
* C = copy
* V = edit value
* D =
* G = Drag, not to loose connection when moving parts
* backspace = remove component
* W = create a wire from the place you are

Click on the following button
+
Checks
* grid
* mm

1. Place symbole (ampli-op button)
2. In the library choose your element
* R = rotate
* click when ok with positiob
* The adding window appear again, choose if adding again or not (esc if not)
3. Hover over the element and click **M** to move
4. To remove, right-click -> remove
5. When placing a resistance, the value does not impact at the beginning
6. Adding a capacitor on VCC to filter power input. 1uF is a good general value but check the datasheet of IC
mm
#### Labels
Used to route signal limiting wires. Only important thing is that they share the same name.

#### Pull-up/down resistance
Use a 10kOhm resistance as pull up-down
Consumption is of the order of magnitude of nano-amps


#### Generate NETLIST

### PCB Edition


Then check where the components are (maybe outside of the screen)

If there is an error, it means some footprints are missing.

Ex : go back to schematic, delete the footprint from any component. Go back to PCB and click the following button


#### Place approximately components

#### Layers
1. Red = Upper layer
2. F.Silks = unfunctional writing (names etc...)
3. Yello = part with holes

#### Design rules
Some limitations exists due to the manufacture process.
Files -> Board setup


**Clearance** = separation between footprints
tool : 1/64 in = 0.3968 mm -> 0.4mm

**Track Width** = 0.3mm (good value, even a bit big)

**Via** are the info for 2 layers PCB

Some info can be calculated with the PCB calculator

Ex : removing copper from the PCB with milling machine.
* Components separation

If a component has to be put on the other side, click **F** on the component to FLIP it.

#### Create your traces
Select the trace tool

Rules:
* Closest possible but not too much too let the board "breath"
* Connect on the pads better than on the tracks


Make tracks bigger
Edit -> track & wire properties
Click tracks
Set to specify value or Set to netclass value

**Cleaning tracks**
Edit -> Clean-up tracks and vias

#### Debug your tracks


Issue : edge to close to the board -> at the moment no problem.

#### Create the board edge
* Select "edge.cut" layer
* We are going to draw

1. Create a 1/4 circle
2. Copy/paste on all sides

Finish created the yellow board line

#### Check the final aspect

Check the board with the BUG

Check the 3D part
ALT3 gives the 3D view

## Prepare

### Oscar's way
Adding a plugin to Kicad
https://gitlab.com/fablabbcn-projects/electronics/kicad-exports
Creates SVG
Then a command creates the PNG
Then rolland

### Josep's way
#### Export as SVG
File -> Export -> SVG
Using this configuration

#### Open Inkscape
Open SVG file

Open Layer tab

Add layers (+ button)

Split objects between layers

Create a big black square

For exporting, select outerline in Selection, then select "custom".
Select the layer you want to export
Export

### SVG Export

### Make PNG

## Global Class
### Inventory
**Wires** : warning with full core coper or "tressé" depending on frequency
**Resistors** : value, power dissipation, process for fabrication (10kOhm for LED -> 5mA at 5V)
**Capacitor** : block steady current. Used as filters (1-10uF) (low frequency).steady voltage, no curren - voltage variation = current. There is polarized and not polarized Capacitors. Main package = 1206 (in inches) -> good to fit a track below. If the capac is big enough it can act as a sall battery
* C = Q/V
* Q =CV
* I = C * dV/dT
Polarized capa are a bit more complex (10F), smaller max voltage.
**Crystals** : to set up specific timing (if IC clock not sufficient)
**Inductors** : block high frequency current
* V=L*dI/dT

**Diodes** : anode/cathode. Let the current in one direction only. Ideal diode is perfect conductor. But not true. When dV>0.6V --> perfect conductor.
* Perfect diode
* Zener diodes (symetric behavior)
* LED diode

**Transistors** : electrical switch.
* MOFSE : Drain, Gate, Source, maximum current handled, RDS (resistance between Drain and Source). The Gate control the resistance between Drain and Source.
**Regulators** : Are used to manage the power source to adapt it to the microcontroller. Input 6-30V -> output 5V. It works with Capa before and after
**OpAmp** :
**MicroControllers** :
### Circuits
**Kirchoff law** :
* Sum of current = o at a node
* Sum of voltage around a circuit = 0v
* P= UI = I^2 * R

UNDERSTANDING Ciruits : http://falstad.com/circuit/

## Thursday - Local Class
### What is a microcontroller

### Transistor

### Circuits
**Combinational** circuit
No memory, not aware of their state. input -> output
**Sequential** circuit
Memory of their state (combinational circuit + state memory)

### Advanced electronic components

#### Capacitor


#### Diodes
Important to READ the link : https://lcamtuf.coredump.cx/electronics/#19

2 important diodes
* Zener diodes
* for USB, computer connetion
* they allow a littlebit of backward current
* Good for protection during connection
* Schottky diodes
* Normal diodes provok voltage drop
* Schottky diodes do not provok voltage drop

#### Oscillators
Oscillator : does not have capacitor included
Resonator : has capacitor included

Can generate pulse signal to impose signal to a microchip.


Fuses are the commands we send to the microchip to tell him his hardware configuration

#### Regulators
Most common one is LDO
Not combinable with PWM

#### How to design the board
1. We have to know how to program it
2. Think about input current depending on the use
3. Choose MC (ATtiny 3216 32 = memory / 16 = pins):
1. Inputs : digital / analog
2. Outputs : how many ? what can they do ? (PWM, Emission ...)
3. Processing power (16Mhz ok for motor controller)