Cron is a time-based job that runs in the background at specific intervals or designated times. It allows you to run tasks and scripts automatically, making cron useful for automating maintenance-related tasks. Therefore, it is a very popular server administration tool.
Cron is present in all Linux distributions. However, if it is not installed, you can install it using apt:
The KY-023 is an easy-to-use analog joystick. The joystick uses a biaxial potentiometer to control the X and Y axis. It also has an integrated push button. In this tutorial, it is shown how to connect the KY-023 joystick with the Arduino and how to use it.
A potentiometer is a simple knob that provides a variable resistance, which we can read into the Arduino board as an analog value. They can be attuned from zero ohms to whatever maximum resistance that is specific to it. For example, a potentiometer of 10 kΩ can be adjusted from 0 Ω to its maximum of 10 kΩ.
Today we are going to speak about push buttons, the wiring and how to implement the code for this circuit elements in Arduino. Push buttons connect two points in a circuit when you press them. That means that logic state of the circuit change when you press and keep pressed the button.
A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow and adjust signal levels among other uses. Resistance is measured in Ohm with a sign of Ω.
A microcontroller (e.g. Arduino) utilizes I/O signals for communication with external hardware devices, where the most commonly known being GPIO. As a reminder, digital logic circuits have three logic states: high, low and floating (or high impedance). When there’s nothing connected to your GPIO pins, your program will read a floating impedance state, which we do not want. To achieve either high or low states, we’ll have to implement pull-up or pull-down resistors in our digital circuit.
Having two or more Arduino boards be able to communicate with each other wirelessly over a distance opens lots of possibilities like remotely monitoring sensor data, controlling robots, home automation and the list goes on. A good, reliable and inexpensive solution is NRF24L01.
The NRF24L01+ is a newer version of the NRF24L01, capable of doing an extra 250kbps of on-air data rate while the one without “+” has only 1Mbps and 2Mbps. Both versions can be mixed together as long as 1 or 2 MBps is being used as the data rate.
Generally, OpenSSL is used for CSR generation on Linux-based web servers (Apache or Nginx) So, if the default web server is installed, there should be no issues with using OpenSSL as it is installed by default on these web servers.
The RSA key algorithm is the algorithm most widely used in digital security. It's an asymmetric cryptography algorithm. This basically means that there are two keys involved while communicating, i.e., the Public key and Private key.
Arduino is an open-source electronics platform based on easy-to-use hardware and software. Arduino boards are able to read inputs - light on a sensor, a finger on a button, or a Twitter message - and turn it into an output - activating a motor, turning on an LED, publishing something online. You can tell your board what to do by sending a set of instructions to the microcontroller on the board. To do so you use the Arduino programming language and the Arduino Software (IDE).
An Apache web server can host multiple websites on the SAME server. You do not need separate server machine and Apache for each website. This can be achieved using the concept of Virtual Host or VHost.
Any domain that you want to host on your web server will have a separate entry in Apache configuration file.
Swap space is the area on a hard disk. It holds memory pages that are temporarily inactive. Swap space is used when your operating system decides that it needs physical memory for active processes and the amount of unused physical memory is insufficient. When this happens, inactive pages from the physical memory are then moved into the swap space, freeing up that physical memory for other uses.
