In the previous tutorial, we have seen how to write our own sketch for a circuit of our own. We have also seen some new functions and how to use those functions as per our requirement. Calculus early transcendentals 3rd pdf. In this tutorial, we will see a new topic called Serial Communication. We will see how to transfer data between Arduino UNO and a computer.
The SoftwareSerial library has been developed to allow serial communication on other digital pins of the Arduino, using software to replicate the functionality (hence the name 'SoftwareSerial '). It is possible to have multiple software serial ports with speeds up to 115200 bps. First up is serial communication. This is pretty simple. I expected there to be more hitches, but it turned out to be pretty straight forward. Well let's get to it. First things first, HERE is the Arduino playground page for serial communication. You might want to read up on the different commands you have there.
Before going further in the tutorial, first we will discuss about what communication is in general. Communication is nothing but exchange of information between two devices. Here, the information is nothing but data which can be anything like text documents, images, audio or video files etc. Data can be sent or received between two systems or devices and it is in the form of bits i.e. 0’s and 1’s.
Hundreds of communication protocols have been defined to achieve this data exchange. Each protocol can be categorized into one of the two categories: parallel or serial. Parallel Communication. Parallel connection between the Arduino and peripherals via input/output ports is the ideal solution for shorter distances up to several meters. Driving an LED on/off using command coming from the Serial communication with Arduino. In the programs above we used Serial.print and Serial.println to print data to the Arduino serial interface. In order to implement a simple two-way communication we also have to be able to read from the serial interface. See the Arduino serial lab, the Serial Input to the P5.js IDE lab or the Serial Communication with Node.js lab for more on sending serial from Arduino to another computer. When two devices are communicating serially, they can’t read each other’s program logic. They can only read what the other device has said.
There are many types of protocols that are used in transferring data between two devices, but all these protocols are based on either Parallel Communication or Serial Communication.
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Parallel communication is a method of transferring multiple bits of data simultaneously using more number of data lines. Some of the common examples of parallel communication are olden day’s printers and hard disks. Even RAMs in modern computers use parallel communication as it increases the speed of data transmission by using separate channel for each bit to be transmitted.
But these high speed data transfers in parallel communication requires more number of wires and also the distance of communication is very less i.e. they cannot be used for long distance communication.
Apart from the on board communications like RAM, graphics cards and other PCI connections, all other devices like printers, hard disks, Ethernet etc. use serial communication. This is because, unlike parallel communication, serial communication transfers one bit of data at a time over two to four wires depending on the protocol.
Even though the data transfer speeds in serial communication is very less when compared to that of parallel communication, this speed is sufficient for devices like printer, hard disk, mouse etc.
The main advantages of serial communication over parallel communication are longer distance communication, less number of wires for communication, reduction in hardware complexity etc.
When coming to Arduino, the communication between Arduino UNO (or any other board) and computer is serial communication.
Wifi survey app mac. The main purpose of this serial communication is to transfer the sketch from computer to Arduino, send information to computer etc.
The most common type of serial communication protocol is UART i.e. Universal Asynchronous Receiver Transmitter. The UART connection requires a 9 pin DE – 9 Connector. But, most modern computers and laptops do not include these COM ports. Hence, if we want to connect our microcontrollers like 8051, AVR or ARM, we need to use an external serial to USB converter.
But Arduino UNO has an on board serial to USB converter and hence we can directly connect the Arduino to the computer. Using this USB connection and Arduino IDE, we can send data to Arduino or receive data from Arduino. This data can be monitored with the help of Serial Monitor in the Arduino IDE.
Now that we have some idea about serial communication, we write a program for communication between Arduino and the computer. For this we will modify the button – LED program we used in the previous tutorial.
In this sketch, whenever the button is pressed, the LED connected to the Arduino is turned on. In this tutorial, we will perform the same operation with an additional task of transferring the status of the button to the computer and printing it on the terminal or serial monitor.
In Arduino environment, in order to begin or initiate the serial communication, we need to use a predefined function called “Serial.begin”.
Serial.begin is a function that is used to begin the serial communication and also set the data transfer rate for communication.
The syntax of Serial.begin is Serial.begin (baud rate);
In the syntax, the baud rate indicates how many bits we are going to transfer in one second. The units of baud rate is bits per second (bps) and the common values of baud rate are 9600 bps, 19200 bps, 115200 bps etc.
The preferred baud rate in most devices is 9600 bps and the default value in Arduino’s serial terminal is also the same. Hence, in the sketch, we will initialize the serial communication by writing Serial.begin (9600); in the setup function.
After initializing the serial communication, the next step is to send data to the serial terminal of the Arduino, which will be displayed on the computer screen. In order to do that, we need to use another function called “Serial.println”.
Using Serial.println function, we can transmit data from the Arduino to computer that can be seen on the serial monitor. The syntax of Serial.println function is Serial.println (“Data”);
In place of Data in the Serial.println function, we have to write the actual data that has to be transmitted. For example, if we want to transfer the data as “Train no: 1234”, then we have to submit Serial.println (“Train no: 1234”);
Coming back to the tutorial, in the button – LED program, we turn on the LED after checking for the status of the button in the “if – else” statement. For the purpose of the tutorial, we are going to do the same thing along with printing the status of the button in the serial monitor.
The modified sketch is shown above. In this sketch, we have modified the “if – else” statement to send the necessary data as per the status of the button. If the condition in the “if” statement is true i.e. if the button is pressed, the LED is turned on and also the status of the button is transferred to computer as “button pressed”. Similarly, when the condition is false, the LED is turned off and serial data is transmitted as “button not pressed”.
In the next tutorial, we will continue exploring features of Arduino by utilizing the Analog Input feature of the Arduino and also the PWM function of Arduino.
In our previous tutorial learned about SPI communication in Arduino. Today we will learn about another Serial Communication Protocol: I2C (Inter Integrated Circuits). Comparing I2C with SPI, I2C has only two wires while SPI uses four and I2C can have Multiple Master and Slave, while SPI can have only one master and multiple slaves. So there are more than one microcontroller in a project that need to be masters then I2C is used. I2C communication is generally used to communicate with Gyroscope, accelerometer, barometric pressure sensors, LED displays etc.
In this Arduino I2C tutorial we will use I2C communication between two arduino boards and send (0 to 127) values to each other by using potentiometer. Values will be displayed on the 16x2 LCD connected to each of the Arduino. Here one Arduino will act as Master and another one will act as Slave. So let’s start with the introduction about I2C communication.
What is I2C Communication Protocol?
The term IIC stands for “Inter Integrated Circuits”. It is normally denoted as I2C or I squared C or even as 2-wire interface protocol (TWI) at some places but it all means the same. I2C is a synchronous communication protocol meaning, both the devices that are sharing the information must share a common clock signal. It has only two wires to share information out of which one is used for the cock signal and the other is used for sending and receiving data.
How I2C Communication works?
I2C communication was first introduced by Phillips. As said earlier it has two wires, these two wires will be connected across two devices. Here one device is called a master and the other device is called as slave. Communication should and will always occur between two a Master and a Slave. The advantage of I2C communication is that more than one slave can be connected to a Master.
The complete communication takes place through these two wires namely, Serial Clock (SCL) and Serial Data (SDA).
Serial Clock (SCL): Shares the clock signal generated by the master with the slave
Serial Data (SDA): Sends the data to and from between the Master and slave.
At any given time only the master will be able to initiate the communication. Since there is more than one slave in the bus, the master has to refer to each slave using a different address. When addressed only the slave with that particular address will reply back with the information while the others keep quit. This way we can use the same bus to communicate with multiple devices.
The voltage levels of I2C are not predefined. I2C communication is flexible, means the device which is powered by 5v volt, can use 5v for I2C and the 3.3v devices can use 3v for I2C communication. But what if two devices which are running on different voltages, need to communicate using I2C? A 5V I2C bus can’t be connected with 3.3V device. In this case voltage shifters are used to match the voltage levels between two I2C buses.
There are some set of conditions which frame a transaction. Initialization of transmission begins with a falling edge of SDA, which is defined as ‘START’ condition in below diagram where master leaves SCL high while setting SDA low.
As shown in the above diagram below,
Canon mf4350d driver for windows 10. The falling edge of SDA is the hardware trigger for the START condition. After this all devices on the same bus go into listening mode.
In the same manner, rising edge of SDA stops the transmission which is shown as ‘STOP’ condition in above diagram, where the master leaves SCL high and also releases SDA to go HIGH. So rising edge of SDA stops the transmission.
R/W bit indicates the direction of transmission of following bytes, if it is HIGH means the slave will transmit and if it is low means the master will transmit.
Each bit is transmitted on each clock cycle, so it takes 8 clock cycles to transmit a byte. After each byte either sent or received, ninth clock cycle is held for the ACK/NACK (acknowledged/not acknowledged). This ACK bit is generated by either slave or master depending upon the situation. For ACK bit, SDA is set to low by master or slave at 9th clock cycle. So it is low it considered as ACK otherwise NACK.
Where to use I2C communication?
I2C communication is used only for short distance communication. It is certainly reliable to an extent since it has a synchronised clock pulse to make it smart. This protocol is mainly used to communicate with sensor or other devices which has to send information to a master. It is very handy when a microcontroller has to communicate with many other slave modules using a minimum of only wires. If you are looking for a long range communication you should try RS232 and if you are looking for more reliable communication you should try the SPI protocol.
I2C in Arduino
The image below shows the I2C pins present in Arduino UNO.
Before we get start into programming I2C using two Arduino. We need to learn about the Wire library used in Arduino IDE.
The library <Wire.h> is included in the program for using the following functions for I2C communication.
1. Wire.begin(address):
Use: This library is used for making communication with I2C devices. This Initiate the Wire library and join the I2C bus as a master or slave.
Address: The 7-bit slave address is optional and if the address is not specified, it joins the bus as a master like this [Wire.begin()].
Serial Communication Programs Arduino Code
2. Wire.read():
Use: This function is used to read a byte that was received from master or slave device, either that was transmitted from a slave device to a master device after a call to requestFrom() or was transmitted from a master to a slave.
3. Wire.write():
Use: This function is used to write data to a slave or master device.
Slave to Master: Slave writes data to a master when Wire.RequestFrom() is used in master.
Master to Slave: For transmission from a master to slave device Wire.write() is used in-between calls to Wire.beginTransmission() and Wire.endTransmission().
Wire.write() can be written as:
value: a value to send as a single byte.
string: a string to send as a series of bytes.
data: an array of data to send as bytes
length: the number of bytes to transmit.
Find nikon lens serial number. 4. Wire.beginTransmission(address): Oasis montaj crack.
Use: This function is used to begin a transmission to the I2C device with the given slave address. Subsequently, build queue of bytes for transmission with the write() function and then transmit them by calling endTransmission() function. 7-bit address of the device is transmitted.
5. Wire.endTransmission();
Use: This function is used to end a transmission to a slave device that was begun by beginTransmission() and transmits the bytes that were queued by Wire.write().
6. Wire.onRequest();
Use: This function gets called when a master requests data using Wire.requestFrom() from the slave device. Here we can include Wire.write() function to send data to the master.
7. Wire.onReceive();
Use: This function gets called when a slave device receives a data from a master. Here we can include Wire.read(); function to read the data sent from master.
8. Wire.requestFrom(address,quantity);
Use: This function is used in the master to request bytes from a slave device. The function Wire.read() is used to read the data sent from the slave device.
address: the 7-bit address of the device to request bytes from
quantity: the number of bytes to request
Components Required
Circuit DiagramWorking ExplanationSkype
Here for demonstrating I2C communication in Arduino, we use Two Arduino UNO with Two 16X2 LCD display attached to each other and use two potentiometers at both arduino to determine the sending values (0 to 127) from master to slave and slave to master by varying the potentiometer.
We take input analog value at arduino pin A0 from (0 to 5V) by using potentiometer and convert them into Analog to Digital value (0 to 1023). Then these ADC values are further converted into (0 to 127) as we can send only 7-bit data through I2C communication. The I2C communication takes place through two wires at pin A4 & A5 of both arduino.
Values at Slave Arduino’s LCD will be changed by varying the POT at master side and vice versa.
I2C Programming in Arduino
This tutorial has two programs one for master Arduino and other for slave Arduino. Complete programs for both the sides are given at the end of this project with a demonstration Video.
Master Arduino Programming Explanation
1. First of all we need to include the Wire library for using I2C communication functions and LCD library for using LCD functions. Also define LCD pins for 16x2 LCD. Learn more about interfacing LCD with Arduino here.
2. In void setup()
3. In void loop()
The received value is read using Wire.read()
We convert that value in terms of one byte as 0 to 127.
Slave Arduino Programming Explanation
1. Same as master, first of all we need to include the Wire library for using I2C communication functions and LCD library for using LCD functions. Also define LCD pins for 16x2 LCD.
2. In void setup()
Next we need to call the function when Slave receives value from master and when Master request value from Slave
3. Next we have two functions one for request event and one for receive event
For request Event
When Master request value from slave this function will be executed. This function does take input value from the Slave POT and convert it in terms of 7-bit and send that value to master.
For Receive Event
When Master sends data to slave with slave address (8) this function will be executed. This function reads the received value from master and store in a variable of type byte.
4. In Void loop():
We display the received value from master continuously in the LCD display module.
By rotating the Potentiometer at one side, you can see the varying values on LCD on another side:
So this is how I2C communication takes place in Arduino, here we have use two Arduinos to demonstrate not only sending of data but also receiving the data using I2C communication. So now you can interface any I2C sensor to Arduino.
The complete coding for Master and Slave Arduino is given below with a demonstration video
Master Arduino Programming
//I2C MASTER CODE
//I2C Communication between Two Arduino //Circuit Digest //Pramoth.T
#include<Wire.h> //Library for I2C Communication functions
#include<LiquidCrystal.h> //Library for LCD display function LiquidCrystal lcd(2, 7, 8, 9, 10, 11); //Define LCD Module Pins (RS,EN,D4,D5,D6,D7)
void setup()
{
lcd.begin(16,2); //Initilize LCD display lcd.setCursor(0,0); //Sets Cursor at first line of Display lcd.print('Circuit Digest'); //Prints CIRCUIT DIGEST in LCD lcd.setCursor(0,1); //Sets Cursor at second line of Display lcd.print('I2C 2 ARDUINO'); //Prints I2C ARDUINO in LCD delay(5000); //Delay for 5 seconds lcd.clear(); //Clears LCD display Serial.begin(9600); //Begins Serial Communication at 9600 baud rate Wire.begin(); //Begins I2C communication at pin (A4,A5) }
void loop()
{
Wire.requestFrom(8,1); // request 1 byte from slave arduino (8) byte MasterReceive = Wire.read(); // receive a byte from the slave arduino and store in MasterReceive int potvalue = analogRead(A0); // Reads analog value from POT (0-5V) byte MasterSend = map(potvalue,0,1023,0,127); //Convert digital value (0 to 1023) to (0 to 127) Wire.beginTransmission(8); // start transmit to slave arduino (8) Wire.write(MasterSend); // sends one byte converted POT value to slave Wire.endTransmission(); // stop transmitting lcd.setCursor(0,0); //Sets Currsor at line one of LCD lcd.print('>> Master <<'); //Prints >> Master << at LCD lcd.setCursor(0,1); //Sets Cursor at line two of LCD lcd.print('SlaveVal:'); //Prints SlaveVal: in LCD lcd.print(MasterReceive); //Prints MasterReceive in LCD received from Slave Serial.println('Master Received From Slave'); //Prints in Serial Monitor Serial.println(MasterReceive); delay(500); lcd.clear(); }
Slave Arduino Programming Kodi addons • download kodi.
Total video converter download mac. //I2C SLAVE CODE
//I2C Communication between Two Arduino //CircuitDigest //Pramoth.T
#include<Wire.h> //Library for I2C Communication functions
#include<LiquidCrystal.h> //Library for LCD display function LiquidCrystal lcd(2, 7, 8, 9, 10, 11); //Define LCD Module Pins (RS,EN,D4,D5,D6,D7)
byte SlaveReceived = 0;
void setup()
{
lcd.begin(16,2); //Initilize LCD display lcd.setCursor(0,0); //Sets Cursor at first line of Display lcd.print('Circuit Digest'); //Prints CIRCUIT DIGEST in LCD lcd.setCursor(0,1); //Sets Cursor at second line of Display lcd.print('I2C 2 ARDUINO'); //Prints I2C ARDUINO in LCD delay(5000); //Delay for 5 seconds lcd.clear(); //Clears LCD display Serial.begin(9600); //Begins Serial Communication at 9600 baud rate Wire.begin(8); //Begins I2C communication with Slave Address as 8 at pin (A4,A5) Wire.onReceive(receiveEvent); //Function call when Slave receives value from master Wire.onRequest(requestEvent); //Function call when Master request value from Slave }
void loop(void)
{ lcd.setCursor(0,0); //Sets Currsor at line one of LCD lcd.print('>> Slave <<'); //Prints >> Slave << at LCD lcd.setCursor(0,1); //Sets Cursor at line two of LCD lcd.print('MasterVal:'); //Prints MasterVal: in LCD lcd.print(SlaveReceived); //Prints SlaveReceived value in LCD received from Master Serial.println('Slave Received From Master:'); //Prints in Serial Monitor Serial.println(SlaveReceived); delay(500); lcd.clear(); }
void receiveEvent (int howMany) //This Function is called when Slave receives value from master
{ SlaveReceived = Wire.read(); //Used to read value received from master and store in variable SlaveReceived }
void requestEvent() //This Function is called when Master wants value from slave
{ int potvalue = analogRead(A0); // Reads analog value from POT (0-5V) byte SlaveSend = map(potvalue,0,1023,0,127); // Convert potvalue digital value (0 to 1023) to (0 to 127) Wire.write(SlaveSend); // sends one byte converted POT value to master } Comments are closed.
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