Understanding I2C: The Versatile Communication Protocol for Connected Devices

In the fast-paced world of technology, seamless and efficient communication between electronic components is vital. As devices become increasingly interconnected, the need for reliable and versatile communication protocols becomes even more crucial. One such protocol that has been a cornerstone in connecting various devices is I2C, short for Inter-Integrated Circuit. In this article, we'll delve into the world of I2C, its history, how it works, and its applications in today's interconnected landscape.

A Brief History of I2C:

I2C was developed by Philips (now NXP Semiconductors) in the early 1980s as a means to communicate between different components within a single device. The protocol's initial purpose was to simplify communication between CPUs and peripheral ICs (Integrated Circuits) on a PCB (Printed Circuit Board). Since its inception, it has grown to become a widely adopted serial communication protocol, making it a fundamental part of modern electronics.

How I2C Works:

I2C is a synchronous, half-duplex communication protocol that uses only two wires: a serial data line (SDA) and a serial clock line (SCL). These wires connect all the devices in an I2C network, and each device on the network has a unique address. The simplicity of the protocol and the minimal wiring required make it an attractive choice for connecting multiple devices.

The I2C communication process involves two main types of devices:

1. Master:  The master device initiates and controls communication on the bus. It generates the clock signal and initiates data transfers with slave devices.

2. Slave: The slave devices respond to the master's commands and share data when requested.

I2C Communication Sequence:

1. Initialization: The master device sends a start signal (S) on the SDA line while keeping the SCL line high. This indicates the beginning of a communication sequence.

2. Addressing: The master then sends the address of the slave device it wants to communicate with, along with a read/write bit indicating whether it wants to read from or write to the slave. The addressed slave acknowledges receipt of its address.

3. Data Transfer: Depending on the read/write bit, the master or slave device will take turns sending or receiving data, while the clock signal is generated by the master on the SCL line.

4. Stop Signal: Once the data transfer is complete, the master sends a stop signal (P) on the SDA line while keeping the SCL line high. This indicates the end of the communication sequence.

Advantages of I2C:

1. Simplicity: I2C's two-wire setup simplifies the hardware connections and reduces PCB complexity.

2. Versatility: I2C can support multiple masters and multiple slaves on the same bus, making it suitable for a wide range of applications.

3. Low Power Consumption: The synchronous nature of I2C reduces power consumption compared to asynchronous communication protocols.

4. Hot-Swapping Support: I2C supports hot-swapping, meaning devices can be added or removed from the bus without disrupting the communication of other devices.

Applications of I2C:

I2C finds applications in various industries, owing to its simplicity and versatility. Some common applications include:

1. Embedded Systems: I2C is widely used to connect sensors, EEPROMs, RTCs (Real-Time Clocks), and other peripheral devices to microcontrollers in embedded systems.

2. Consumer Electronics: Many consumer electronic devices, such as smartphones, tablets, and laptops, use I2C to facilitate communication between components and sensors.

3. Industrial Automation: I2C is utilized in industrial automation for interconnecting sensors, actuators, and other control devices.

4. Medical Devices: Medical devices often employ I2C to interface with sensors and control modules, ensuring precise and accurate data exchange.

Conclusion:

In conclusion, the I2C communication protocol has stood the test of time and continues to play a vital role in enabling efficient data transfer between interconnected devices. Its simplicity, versatility, and ability to handle multiple devices on a single bus make it an invaluable tool for engineers and developers across various industries. As technology continues to evolve, I2C will likely remain a fundamental communication protocol in the ever-growing world of connected devices.

How a Thermistor Works?

Thermistor 

A thermistor is a type of resistor whose resistance is dependent on temperature, more so than in standard resistors. The word is a combination of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors (negative temperature coefficient or NTC type typically), self-resetting overcurrent protectors, and self-regulating heating elements (positive temperature coefficient or PTC type typically).

Thermistors are of two opposite fundamental types:

With NTC thermistors, resistance decreases as temperature rises. An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current limiter.

With PTC thermistors, resistance increases as temperature rises. PTC thermistors are commonly installed in series with a circuit, and used to protect against overcurrent conditions, as resettable fuses.

Thermistors are generally produced using powdered metal oxides.[1] With vastly improved formulas and techniques over the past 20 years, NTC thermistors can now achieve accuracies over wide temperature ranges such as ±0.1 °C or ±0.2 °C from 0 °C to 70 °C with excellent long-term stability. NTC thermistor elements come in many styles [2] such as axial-leaded glass-encapsulated (DO-35, DO-34 and DO-41 diodes), glass-coated chips, epoxy-coated with bare or insulated lead wire and surface-mount, as well as rods and discs. The typical operating temperature range of a thermistor is −55 °C to +150 °C, though some glass-body thermistors have a maximal operating temperature of +300 °C.

Thermistors differ from resistance temperature detectors (RTDs) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistors typically achieve a greater precision within a limited temperature range, typically −90 °C to 130 °C.

Controlar LEDS con el PIC16F84A

Configurando los puertos de entrada/salida digitales. El programa propuesto tomará las salidas  por el puerto A y mostrará la salida por la barra de leds conectado al puerto A, simulando las luces de una discoteca. También se realizarán algunas pruebas con operaciones en ensamblador, lectura de tablas y su simulación hasta alcanzar el principal objetivo de la práctica que es la implementación de la misma.

Objetivos:

• Manipular el puertos A  para otorgar datos y utilizar esos datos en una tarea específica con impacto real.
• Practicar de forma física con el PIC16F84A.
• Utilizar retardos en el lenguaje ensamblador para evitar el rebote de los pulsadores.
•  Hacer uso de la herramientas de simulación y diseño de circuitos para realizar una práctica más eficiente.

Materiales:

• 1 PIC16F84A.
• 5 leds RGB
• 1 regulador de voltaje 7805.
• 1 multímetro.
• 1 transistor 2n2222.
•  Resistencias:
•    5 de 330 ohms.
•    1 de 220 ohms.
•    1 de 10k ohms.
• 1 fuente de voltaje.
• 1 Cristal de cuarzo
• 2 capacitores de 22pF
• Grabador MASTER PROG
• Software:
• MPLAB v8.92.
• Proteus 8 Profesional.
• MASTERPROG

Procedimiento:

Planteamiento, asignación de salidas del puerto A:

Secuencia 1: Enciende en forma ascendente los 5 led conectados al puerto A.

El puerto A comienza apagado y se mueve a W el número que enciende el primer led del puerto A: B’00000001’ y se asigna un delay de 2s para que se observe el cambio en la salida, posteriormente se sigue cargando el numero que enciende el siguiente led hasta llegar a tener encendidos todos los bits del puerto A: B’00011111’.

Secuencia 2: Apaga en forma descendente los 5 led conectados al puerto A.

El puerto A comienza apagado y se mueve a W el número que apaga el primer led del puerto A B’00001111’ y se asigna un delay de 2s para que se observe el cambio en la salida, posteriormente se sigue cargando el numero que apaga el siguiente led hasta llegar a tener apagados todos los bits del puerto A: B’00000000’.

Secuencia 3: Realiza un secuencia ascendente y descendente solo con los bits pares (RA0, RA2 Y RA3).

El puerto A comienza apagado y se mueve a W el número que enciende el primer led del puerto A: B’00000001’ y se asigna un delay de 2s para que se observe el cambio en la salida, posteriormente se sigue cargando el numero que enciende el siguiente led par B’00000101’ hasta llegar a tener encendidos los siguientes bits del puerto A: B’00001101’ y por último se debe realizar la misma secuencia pero en sentido contrario apagando los leds hasta que todo el puerto de apague.

Repetir el ciclo.

Código:

Para realizar el programa se tuvo que crear una librería a la que se le asignó el nombre “RETARDO”, en la cual gracias a la ayuda del programa Delay Code Generator se crearon dos retardos, uno de dos segundos y otro de cinco segundos (DELAY2 y DELAY5 respectivamente).

Figura 1: Programa en ensamblador 

Simulación:

Se realizó una simulación en Proteus ISIS para verificar el correcto funcionamiento del programa y así poder implementarlo de manera física:

Figura 2: Simulación en proteus ISIS

Se cargó el programa  con el grabador MASTER PROG:

Figura 3. Grabador MASTER PROG.

Resultados:
Se ensamblo el circuito en un protoboard siguiendo el diagrama de simulación en proteus, se alimentó con una fuente variable GPS-3303 a 5v.

Figura 4: Implementación en un circuito físico.

Conclusiones:

Con base a los procedimientos realizados en esta práctica, nos fue posible llevar un correcto control y dirección del trabajo, aplicando los conceptos de implementación de software y hardware del microcontrolador previamente estudiados en el curso.

Los objetivos específicos de la práctica descritos en la introducción se cumplen satisfactoriamente; se implementaron de forma eficiente los diferentes programas de simulación y de grabación del PIC y asu vez, se hizo un uso correcto de los retardos dentro del programa principal del PIC, logrando de esta manera, que el microcontrolador realizara correctamente la tarea para la cual fue programado.

How to simulate an Arduino project

Nowadays, there are many software to simulate Arduino or electronic projects, but today I am going to show a really easy one. Tinkercad is an online simulation software develop by Autodesk, because it is online, you don´t have to install anything on your device. It has a lot of components and it is totally free, you have to register and then you are ready to begin your simulation projects. Another think that you can do on Tinkercad, is to design 3D objects, I haven´t used yet, but I think it is really a basic program like the new 3D paint on windows.

Features:

• Collaborative projects
• Online and free
• You can share projects with the community
• Easy to use
• On cloud storage
• Interactive
• Code by text or blocks

Now I am going to show you a little example, so you can know the basics.

Controlling a servo with a digital PIN on Arduino

In this example we are going to control a servomotor by using a digital pin on an Arduino board, we are basically to simulate a PWM signal changing states of a digital pin.

In the next image your going to see how a servo can move through different positions just changing the width of the HIGH state on a PWM signal frequency.

First, enter to Tinkercad website and register, once you are registered and have logged in, go to circuit on the main page and create a new Circuit.

Go to the right side and searh for a microverso, a pot and an Arduino board. Like in the image below.

Connect both components: 

Servo	Arduino
Red	5 v
Black	GND
Orange	pin 9

POT

Center   A0

Left       5 v

Rigth     GND

To code our Arduino, we are going to click on the Code button and then click on Text. An IDE window will appear, we are going to put the next code, it is commented, so you can understand it.

//Define pins and variables
#define servo 9
int pot;

void setup()
{
//Setting up the Serial port, so we can see our variable velues
Serial.begin(9600);
//The pin to control our servo as OUTPUT
pinMode(servo, OUTPUT);

}

void loop()
{
 //Using the pot to change our pulse width on HIGH state
 pot= map(analogRead(A0), 0, 1023, 700, 2000);
 //Showing the actual value
 Serial.println(pot);
//Making out PWM pulse, changing from HIGH to LOW for specific periods digitalWrite(servo, HIGH);
 delayMicroseconds(pot);
 digitalWrite(servo, LOW);
 delayMicroseconds(1500-pot);

}

Once you have your code and all setting up, start the simulation. You will see how the servo is moving while you change the value on the potentiometer. Like in the next animation.

This is all, hope you like it and find this information useful.

FreeCAD the open-source CAD Software

Hello everyone, today I´m goint to make a little intorduction to FreeCAD, this program save me when I wasn´t able to use Windows on my computer and also I used in one of my classes.

FreeCAD is an open source 3D modeler, design to make objects of different sizes, it is a good option for hobbyist makers, students and teachers that don´t want to worry about license issues. I have used for a while and I think it has the essential tools to model pieces and printed with a 3D printer.

With this softwae you can run robot simulations and automatize it with you python scripts, also it counts with sketcher for 2D drawing.

FreeCAD supports the next standard formats:

• STEP
• STL
• IGES
• SVG
• DXF
• OBJ
• IFC
• DAE

You can downloaded for Windows, Mac and linux.

Download

For linux you can use:

sudo apt-get install freecad 

References:

https://www.freecadweb.org/

Transfer files from PC to BeagleBone/Raspberry

Last week one of my classmates ask me if he could pass a code from his computer to a BeagleBone or Raspberry Pi because sometimes when he copy some code from his computer and then when he paste the code with nano, the code lost its format.

In this entry I will explain you how to use a program called FileZilla, this program will allow us to connect with our devices and access to the files that we have on them.

Materials:

1.  PC
2. BeagleBone or Raspberry PIconnected to your PC
3. Filezilla software

The first thing we have to do is to install de softwae from the oficial site:

https://filezilla-project.org/

Then click on Download FileZilla Client. After this you have to choose between FileZilla pro and FileZilla free.

After downloading and installing you must see a window like this :

Now we have to fill the blank spaces, server is the ip of your device (Raspberry Pi or BeagleBone), you user name, for example on BeagleBone could be "debian" and for the Raspbery Pi could be "pi". Your username password and the port, most of the times the port used is 22.

After filling all the requirements just click on connect and the files of your device will appear at the rigth corner, like in the next image:

Once you are connected you can move, copy and delete files.

Comment and share if you find this useful.

PIC Delay Code Generator (assembly)

One of the most laborious things that we deal with PICs on assembly code, is to make delays. I am going to share you a program that I made for my course of microcontrollers.

I made this program using MATLAB, it comes in a ejecutable form, but your computer must has installed a MATLAB distribution upto 2015 or later.

Here is the interface that you are going to see when you run the DELAY.exe file.

Time (tiempo) is the delay time that you want to generate, it can be on seconds or cycles (segundos and ciclos). Also you must specify the type of your clock in Mhz (tipo de reloj) and the name of your constants (constante 1, 2,3). Finally you just put the name of the rutine (nombre de la rutina) and click on generate code (generar código)

After configuring all and clicked, you are going to see the generated code, you just have to copy it and paste it on your script.

DONWLOAD HERE

COMMENT AND SHARE IF YOU FIND THIS USEFUL

Bluetooth module HC - 06 on Raspberry Pi

On my last blog I published an easy way to use your smartphone as a GPS module using a Bluetoth module to communicate with different boards, but I realize that some people doesn´t know how to configure and connect the Raspberry Pi to the HC - 06 module. So, in this blog that´s what we are going to do.

Materials:

1. Raspberry PI
2. HC - 06 Bluetooth module
3. Wires
4. Computer with ssh connection program.

Buy here:

Baoblaze 3 piezas HC-06 Wireless 6 Pin Bluetooth 4.0 Serial Módulo para Arduino Android IOS

Process: 

First we are going to configure our UART port on our Rasberry Pi, this is because by default raspbian has configured its baud rate to 115200 bps and our module use 9600 bps.

Following some instructions from Miguel Bringerg and his very useful blogs I did it in this way:

NOTE: The instruction to open and edit files is: sudo nano -file direction-

1. First, we are going to open the file /boot/cmdline.txt , and change the options console and kgbdoc  from 115200 bps to 9600 bps.
2. Now we go to a second file /etc/inittab and also change the property of the port that has 115200 bps to 9600 bps.

All we have to do next is to write some example code, I use the pyserial library from python, you can install it using the next instruction:

sudo pip install pyserial

You can find more information about this library in: 

https://pythonhosted.org/pyserial/

In this example I configured my serial port and then I read some data that came with letters to detect the variable that is receiving the module:

NOTE: Your device might be called ACM0 intead of AMA0, to check the devices connected to you board use ls /dev/tty*

The right connection of the module is shown next:

Comment and share if you find this useful.

Using android phone as GPS for Arduino and Raspberry Pi projects

Sometimes, when we are making projects money is the principal challenge, and components like GPS modules are kind of expensive. Once I was in that situation and I figured the way to fiinish my work, I did it with cheap and common compoenents, a smatphone and a Bluetooth module.

Nowadays, allmost every person has a smartphone and they come with sensors that we can use in our inventions, like IMU, GPS, Cameras, etc. And we can obtain a Bluetooth module for around $4.00 USD.

So, lets begin with this toturial:

Materials:

• HC-06 Bluetooth module

• Android phone
• Raspberry PIor Arduino

Process:

First we are goin to enter to App Inventor, this is a MIT website to create android apps, you are able to log in with your Google account or register with another email.

Once you're logged in, go to start new project. Now that you are in the window of creation you could see a Palette where sensors, buttons and other functions can be added to our app.

We are going to add a ListPicker, WebViewer, Bluetooth Client, Clock and a Location Sensor. Your components and preview have to look like the next screenshot.

On my app I configure the ListPicker like a conecction button, all you have to do is to click on the component and change its properties.

You can change colors, dimensions and another things if you want, but today we are going to make it a little simplier. Now, we have to do the code, don´t worry, this website allows you to program buttons and sensors with blocks. I am going to put some screenshots of each part of the app, you can get blocks from the right corner of the main window. And all fuctions are on the blocks window.

Now the programing:

Connection button:

Clock:

In this image we can see our message that is sended trought our bluetooth module. You can make a script for arduino or python for a Raspberry Pi board, also this could work for BeagleBone.

Now, we can download our app:

Finally, I will leave here an example of how the information can be recieved on an Arduino board.

Comment and share if you found this useful.

State Space to Transfer Function | TI - Nspire

Simulación de un Semáforo con PLC´s