Different types of serial communications

To get familiar, let us take a simple example. For suppose, you want to send a file present in your laptop to smartphone. How would you send? Probably using Bluetooth or WiFi protocol, Right. In the first step, your laptop will search for devices nearby m and will list out the devices found. This process is often called roaming. To connect to your mobile, the pairing has to be done.

The default configuration is already present in the software. So no need to configure the baud rate manually. Beyond this, there are four unknown rules.

They are baud rate, data bit selection framing , start-stop bit, and parity. Baud rate is the speed of transferring data from the transmitter to a receiver in the form of bits per second. Some of the standard baud rates are , , , , Note: The Higher a baud rate, more data can be transferred in less amount of time.

However, I recommend using up to as a safe limit due to mismatch of sampling frequency at the receiver end. Framing shows how many data bits you want to send from the host device Laptop to mobile receiver.

Is it 5, 6, 7, or 8 bits? Mostly many devices, 8 bits are preferred. After selecting the8-bit data chunk, endianness has to be agreed by the sender and receiver.

Transmitter appends synchronization bits 1 Start bit and 1 or 2 Stop bit to the original data frame. Synchronization bits help the receiver to identify the start and end of the data transfer. This process is known as asynchronous data transfer. Data corruption may happen due to external noise at the receiver end.

The only solution to get the stable output is to check the Parity. The most common question that will come to mind when you start working on the embedded system is why to use Asynchronous protocols? As you know, the data stored in the memory are in the form of bytes. You may have a doubt How is the byte-wise data converted to binary bits?

The answer is a Serial port. The serial port has an internal chip called UART. The RS serial port has nine pins, male or female type models.

RS C serial communication interface is the later version of RS Out of 25 or 9 pins, we use only three pins for the connection of terminal devices. We can transfer data only up to 1Mpbs limit using RS To overcome this problem RS comes into the picture. RS is a multi-drop serial interface. It sends data using two twisted pair cables differential configuration. Cable length is feet with a baud rate of 10Mbps.

RS is the industry preferred protocol. Unlike RS, you can connect 32 line drivers and 32 receivers in a differential configuration. The transmitter is also called Line driver.

However, only one transmitter is active at a time. One wire is similar to I2c protocol. But, the difference is one wire protocol uses single data line and ground. It requires no clock signal and the slaves are clocked using internal crystal oscillator.

It provides half duplex communication. One wire uses bit addressing scheme. Serial communication is a communication method that uses one or two transmission lines to send and receive data, and that data is continuously sent and received one bit at a time. Since it allows for connections with few signal wires, one of its merits is its ability to hold down on wiring material and relaying equipment costs.

Of these communication standards, RSC has been widely adopted in a variety of applications, and it is even standard equipment on computers and is often used to connect modems and mice.

Sensors and actuators also contain these interfaces, many of which can be controlled via serial communication. This serial communication standard is widely used and is often equipped on computers as standard. It is also called "EIA". The purpose and timing of the signal lines and the connectors have been defined D-sub pin or D-sub 9-pin.

However, even now it is generally referred to as "RSC". This standard fixes problems in RSC such as a short transmission distance and a slow transmission speed. It is also called "EIAA". For even parity, the parity bit makes the number of 1's even. For odd parity, the parity bit makes the number of 1's odd. Example: The data bits have three 1's.

For even parity, the parity bit should be 1 to make the total number of 1's equal to 4 an even number. For odd parity, the parity bit is 0 since there is already an odd number of 1's. The baud rate, or speed of transmission, is also part of the protocol.

It is important that the sender and the receiver should have the same baud rate. The standard rates are as follows:. I'm not sure why is that but I know that is the maximum serial port speed of old IBM computers popularly know as the first "personal computer".

If you connect a serial output pin which sends a "A" ascii 41 or in binary character to the oscilloscope, this is what you would see on the screen:. If you want to interface your micro to another device which uses serial communication, you need to connect the micro's Tx to the device's Rx and vice versa. The number of UART device varies among microcontrollers. The only way for it to communicate serially is through bit-banging a method of directly sending bits by pulling a pin high or low at a specific length of time.

Example: If you want to send the binary data serially at a speed of 9, baud, you could toggle the state of the Tx pin you assigned based on the binary sequence. The length for which the pin remains on the specified state 1 or 0 would be By experience, software serial is more susceptible to transmission errors than using hardware UART.

The only reason I use software serial is when I need to use multiple serial devices at once. I highly recommend using the hardware UART if you are only using one serial device and your microcontroller supports one.

The Beaglebone Black and Raspberry Pi also contain serial communication hardware. Arduino boards communicate with the PC via USB cable or to other serial devices using the serial pins. Each arduino board has at least one serial port and is at digital pins 0 and 1 Tx and Rx respectively. Using these pins while loading a program to the board causes an error because it's the same pins for USB connection.

This is why it's a bad idea to connect the arduino's serial pins directly to a PC's serial port. The USB port which is also serial also uses different voltage levels and protocol. The AnalogReadSerial example is one of the best starting points in understanding how to use the arduino's serial port.

This example reads analog voltage at pin A0 and stores it to the variable sensorValue. The sensorValue is now visible in the serial terminal via the Serial. If you want your arduino to receive data, you'll be using the Serial. For more information on arduino's serial functions, check out the official documentation Arduino Serial. Running out of pins to use is common in microcontroller programming. This is especially true for the Arduino UNO which has only one serial port.

The GSM module in fact uses software serial to communicate witht the arduino board. You can assign whichever pins are available for use as Tx and Rx pins! The above code assigns the serial pins to digital pins 10 and Once there is s software serial object, you can now use the functions of the library which are the basically the same functions as with hardware serial.

The only way to implement it is through software.