Secure Digital (SD) is a memory card format for portable devices such as digital cameras, mobile phones, laptops and even game consoles (both desktop and laptop), among many others.

SDHC Speed Class 2 Class 2 2 MB/s
SDHC Speed Class 4 Class 4 4 MB/s
SDHC Speed Class 6 Class 6 6 MB/s
SDHC Speed Class 10 Class 10 10 MB/s
UHS Class 1 UHS Class 1 10 MB/s
UHS Class 3 UHS Class 3 30 MB/s

When we talk about RJ45 ("Registered Jack" 45) we refer to a telecommunications network interface for wired connection of voice and data equipment.

This connector has 8 pins or connections and may have a specific category depending on the data transfer speed and bandwidth (category 5e, 6, etc.)

The common application is their use in Ethernet network cables under TIA/EIA-568-B standard that defines the arrangement of pins (pinout), but can also be used for other applications.

- Direct pin diagram:

EIA-568A
Pin No.1: WHITE-GREEN
Pin No.2: GREEN
Pin No.3: WHITE-ORANGE
Pin No.4: BLUE
Pin No.5: WHITE-BLUE
Pin No.6: ORANGE
Pin No.7: WHITE-BROWN
Pin No.8: BROWN

EIA-568B
Pin No.1: WHITE-ORANGE
Pin No.2: ORANGE
Pin No.3: WHITE-GREEN
Pin No.4: BLUE
Pin No.5: WHITE-BLUE
Pin No.6: GREEN
Pin No.7: WHITE-BROWN
Pin No.8: BROWN

- Schematic of crossed pins:

The crossover cable has one end with EIA-568A scheme and the other one with EIA-568B.

Depending on the quality and type, network cables are classified into categories that help us know the characteristics of them.

The categories of network cables most commonly used are:

- Category 5
- Category 5e
- Category 6
- Category 6
- Category 7

As can be seen, category 5e (enhanced or improved) and category 6A (Augmented), are an improvement of categories 5and 6, respectively, which it has improved the top speed and bandwidth.

The higher the category, the higher the speed of maximum data, the maximum 100 meters distance as its standard.

You can see a table which shows the 5 categories, where V is the maximum velocity, D is the maximum and MHz frequency which can work away.

Arduino is defined as a combined system between hardware and software, which allows users with or without programming knowledge to create projects from scratch. Thanks to its low cost and its wide range of accessories, it has become one of the most appreciated devices by the creative community or called makers (creators).

Within the Arduino range we can find different devices, which will allow us to easily create projects that perform different functions. Its open source GNU free access is essential in the maker community, which allows its creator to develop almost any prototype he can think of.

Arduino was created with the aim of reducing and lowering the material costs needed by interactive design students from Ivrea, Italy, since the devices they used previously were very expensive. This new Arduino project reduced the cost of the material each student needed and eventually became a commercial product as we know it today.

These small plates consist of a SRAM memory, with its own flash storage system (EEPROM), microcontrollers and a microprocessor, currently we can find different processors for the most current models, such as processors:

- 8-bit Atmel AVR
- 32-bit ARM Cortex-M0+
- 32-bit ARM CortexM3
- Intel Quark (x86) 32-bit

Arduino has an open source programming software called the Arduino IDE, with which anyone can create the basis of a new project. Both software and hardware are compatible with Windows, MacOS, and Linux operating systems. Its programming only requires a USB connection to the PC and the free programming software.

Among the different devices we can find the main Arduino board, the nerve center of any project, among which we can find:

- Arduino Uno R3
- Arduino Leonardo
-Arduino 101
- Arduino Explore
-Arduino Zero
- Arduino Mega 2560
-Arduino Due
-ArduinoMicro
- Arduino Nano
- Arduino MXR 2 UNO Adapter
- Arduino MKR Zero
- Arduino Yun
- Arduino Ethernet among others



In order to expand its functionality, we have a wide range of shields or modules that allow you to expand its functionality, such as screens, Wi-Fi modules, etc. these can be attached to the Arduino board itself, thus allowing it to read inputs and send data outputs. Among some shields we can find:

- Xbee wireless modules
- USB ports
- Sensors
- Breadboard
- Card readers
- WiFi connection
- Motors or servos
- Ethernet connection
- GPS module
- GSM module
- RS232 module
- Relays
- LCD screens
- Sound and DMX

Among some examples that we can create with Arduino and its external components we can find clocks, scales, alarms, automated irrigation systems, a battery tester, control of mechanical arms and much more.

Thanks to its large community of makers, we can find hundreds of projects to carry out on the net, ideal for delving into the world of electronics and programming, whether at an educational, professional or domestic level.