MicrocontrollerPlayground

A collection of scripts used in combination with various micro controllers (and a Raspberry Pi utilizing it's GPIO pins and systemd).

Setup

Linux (e.g. Arch/Manjaro)

Permissions to write to Microcontrollers

# Find device
ls /dev/ttyACM*
ls /dev/ttyUSB*
# Give user write permissions:
# e.g. /dev/ttyACM0: (Arduino UNO R3)
sudo chmod a+rw /dev/ttyACM0

The permissions can also be done permanently by adding the current user to the uucp group (provides access to serial ports, USB serial devices, etc.):

sudo usermod -a -G uucp $USER

Basics

Prototyping Tools

Breadboard

A breadboard is a reusable platform for quickly building and testing electronic circuits without soldering.

The holes on the outer 2 columns are vertically connected while the ones in the 2 inner columns are connected horizontally (sometimes the red and blue lines have a space in the middle meaning that there the lines are disconnected).

Jumper Cables

A jumper cable is an insulated wire (which is able to conduct electricity) with an exposed connector on both endings. Plugging the connectors inside the holes of a breadboard makes it possible to create quickly electrical connections between components. The insulation is important to prevent accidental contact with other wires (or other electrical conducting components) and electrical shocks.

Important

Humans generally cannot get an electric shock from extra-low voltage systems (like the 5V output of a Raspberry Pi) as the voltage is too low to overcome the resistance of human skin under normal conditions.

$16mA$ is the most a human can experience while still being able to let go and not take permanent damage.

Still the resistance of human skin drops dramatically when being wet or damaged to as low as $500\Omega-1k\Omega$¹

$$ \overbrace{I\text{ (Current)} = \dfrac{V\text{ (Voltage)}}{R \text{ (Resistance)}}}^\text{Ohm's law}: $$

$$ \begin{aligned} \dfrac{5V\text{ (Voltage Raspberry Pi)}}{100k\Omega \text{ (Resistance human dry skin)}} &= 50 \mu A \text{ (harmless)}\\ \dfrac{5V\text{ (Voltage Raspberry Pi)}}{1k\Omega \text{ (Resistance human wet skin)}} &= 5 mA \text{ (noticeable but not yet dangerous)}\\ \end{aligned} $$

Theory

Electric Current

Electric current is the flow of electric charge (usually electrons) through a conductor like a wire.

TODO

Conductor

TODO

Ohm's Law

Ohm's law describes the relationship between voltage, current, and resistance in a circuit: $$ I(\text{Current in amperes }[A]) = \dfrac{V(\text{Voltage in volts }[V])}{R (\text{Resistance in ohms}[\Omega])} $$

Power

It’s how much energy is used per unit of time: $$ P (\text{Power in watts}[W]) = V(\text{Voltage in volts }[V]) \cdot I(\text{Current in amperes }[A]) $$

Kirchhoff's circuit laws

Kirchhoff's circuit laws are two equalities that deal with the current and potential difference (commonly known as voltage) in the lumped element model of electrical circuits.

TODO

AC/DC

TODO

Basic Electronic Components

Resistor

A resistor is an electronic component that limits or regulates the flow of electrical current in a circuit. It is used to control voltage and current levels, protect components from excessive current, and create voltage drops.

Capacitor

Stores and releases electrical energy; often used for smoothing voltage or timing circuits.

Diode

Allows current to flow in only one direction, commonly used in rectifiers.

Transistor

Acts as a switch or amplifier in circuits, key to microcontroller operation.

Advanced Electronic Components

LED

TODO (RGB LED)

Button

TODO

Communication Protocols

Microcontrollers communicate with other devices using the following protocols (they define how data is transmitted and received using electrical signals):

I2C ($I^2C$)

TODO

SPI

TODO

UART

TODO

Microcontroller Inputs/Outputs

Output Pins

TODO (High/Low, PWM, Digital, Analog)

Input Pins

TODO (Digital, Analog Inputs)

Sensors

DHT22

TODO

LCD Display

TODO

...

Footnotes

1. https://www.cdc.gov/niosh/docs/98-131/ Publication No. 98-131: Worker Deaths by Electrocution (PDF). National Institute for Occupational Safety and Health. Retrieved 2024-12-14. (archived: https://web.archive.org/web/20081011191854/http://www.cdc.gov/niosh/docs/98-131/pdfs/98-131.pdf) ↩