What is Asio?
Asio is a cross-platform, open-source C++ library. It is an underrated C++ library designed for input, output, and networking purposes. Asio stands for asynchronous input-output. Christopher M. Kohlhoff developed Asio in 2003. It is released under Boost Software License. Multiple platforms support Asio, including Windows, Linux, macOS, and FreeBSD.
Multiple projects have used Asio, including the WebSocket framework, Osiris, CodeShop, JukeFly, and Web toolkit. There are two variants of Asio involving the Boost.Asio and non-boost Asio. Boost is another library of C++.
Asio Serial ports
When discussing computers and input-output, it is important to mention serial ports. Serial ports are used to connect the input-output devices to a computer. The Asio library in C++ provides us the functionality to specify what to do with the i/o devices connected via serial ports.
The Asio library contains various classes for manipulating and creating serial ports. You can use the various free functions available in Asio. Some of these functions are read(), write(), read_until(), async_read(), async_write(), or async_read_until().
You can open a serial port using the below command.
serial_port port(my_io_context, name);
serial_port is an alias or typedef of basic serial usage.
typedef basic_serial_port serial_port;
The basic_serial_port is a wrapper or abstraction of all the serial port functionality. It contains various functions that you can use to create and manipulate serial ports.
Some of the functions of serial_port are:
assign(), async_read_some(), async_write_some(), close(), open(), write_some(), set_option(), etc.
The serial_port_base class in Asio is used as a base for basic_serial_port. It provides a common place to specify the serial port options.
The serial_port_base class is used to set five main serial port options, they are:
- baud_rate
- character_size
- flow_control
- parity
-
stop_bits
We will discuss each of these options in brief now.
serial_port_base::baud_rate
The baut_rate class of the serial_port_base is used to set the baud rate. The speed at which data is sent through a communication medium is known as the baud rate.
The important member functions of this class are:
- baud_rate() - constructor of this class, sets the rate to 0.
- load()
- store()
-
value()
serial_port_base::character_size
The character_size class in Asio provides us with the functionality to change the character size for any serial port. You can increase or decrease the character size as per your needs.
The important member functions of this class are
- character_size() - constructor of this class sets the size as 8.
- load()
- store()
-
value()
serial_port_base::flow_control
This class sets or changes the flow control for a serial port in Asio. The flow control is defined as the amount of data transferred through a serial port. It includes both the input and the output data.
Some devices cannot process as fast as the computers they are connected to, so in such cases, you need to define an appropriate flow control factor to ensure that the data is not lost.
The important member functions of this class are
- flow_control() - constructor of this class.
- load()
- store()
-
value()
serial_port_base::parity
The parity class is used to change the parity for any serial port in Asio. Parity is a method of checking transmission errors. You are taking input and giving output, so there is a chance of error. You can use the parity class for this purpose.
The important member functions of this class are
- parity() - constructor of this class.
- load()
- store()
-
value()
serial_port_base::stop_bits
The stop_bits class in serial_port_base of Asio is used to change or set the number of stop bits. The stop bits specify the end of the frame being transferred by the serial port. Using this class method, you can set the value of the number of stop bits.
The important member functions of this class are given below.
- stop_bits() - the constructor of this class, which sets the number of stop bits as one.
- load()
- store()
- value()
Also read about, Abstract Data Types in C++ and Application of Oops
Frequently Asked Questions
What is Asio?
Asio is a cross-platform, open-source C++ library. It is an underrated C++ library designed for input, output, and networking purposes. Asio stands for asynchronous input-output. Christopher M. Kohlhoff developed Asio in 2003.
What is error control?
When data is transmitted, it is necessary to check for errors; this is called error control. There are various ways of checking errors in received data. Some methods are checksums and parity.
Why do we need flow control?
Some devices cannot process as fast as the computers they are connected to, so in such cases, you need to define an appropriate flow control factor to ensure that the data is not lost.
Asio is written in which language?
Asio is written in C++ as it supports objected oriented programming. It has various classes to perform certain functions specific to i/o and networking.
Is C++ a fast programming language?
C++ is a fast programming language compared to other high-level languages like Java and Python.
Conclusion
This article discussed the Asio library of C++. We have discussed serial ports in Asio, and we have also discussed the important classes to set the basic options for serial ports in Asio.
To learn more about C++ and programming, visit the below articles.
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