serial communication on atmega3216

Description: A basic introduction to RS232-based serial communication on the ATmega32/16 using the USART hardware. It is recommended to have the ATmega32 datasheet available for reference. Serial communication involves transmitting data one bit at a time across a communication channel, in contrast to parallel communication, which sends multiple bits simultaneously. While parallel communication is faster and easier to understand, it incurs higher cabling costs, prompting a shift towards serial communication. RS232 is a protocol that defines the standards for sending control signals between transmitters and receivers in serial communication. The 9-pin male socket on a desktop CPU serves as a serial port that utilizes RS232 for communication. The USART (Universal Synchronous and Asynchronous Receiver and Transmitter) is a hardware component that facilitates serial communication, commonly found in microcontrollers. Serial communication underpins various systems, including cell phones, printers, and Distributed Control Systems, employing protocols such as RS232, RS485, I2C, SPI, and Token-passing. In tech events involving image processing and robot control, serial communication is essential. Synchronous serial communication requires a constant external clock for bit transmission, while asynchronous serial communication does not, using start and stop bits to differentiate messages.

Serial communication is a fundamental aspect of modern electronics, particularly in microcontroller applications such as the ATmega32/16. The USART hardware integrated into these microcontrollers allows for effective management of serial data transmission, adhering to the RS232 protocol. This protocol is crucial as it establishes the communication rules necessary for devices to exchange data reliably.

In a typical RS232 setup, the communication channel consists of a transmitter and a receiver, where the transmitter converts parallel data from a microcontroller into a serial format for transmission. The RS232 standard defines electrical characteristics, signal timing, and the physical connector specifications, often represented by a 9-pin D-sub connector. Each pin serves a specific function, such as transmitting data (TX), receiving data (RX), and providing control signals like Request to Send (RTS) and Clear to Send (CTS).

When implementing serial communication using the USART, the configuration parameters must be set correctly. These parameters include baud rate, data bits, stop bits, and parity settings. The baud rate determines the speed of data transmission, while the number of data bits typically ranges from 5 to 9. Stop bits signal the end of a data packet, and parity can be used for error checking.

Synchronous and asynchronous modes of serial communication offer flexibility depending on application requirements. In synchronous mode, a clock signal synchronizes data transmission, ensuring that both the transmitter and receiver operate in unison. This mode is beneficial for high-speed applications where timing is critical. Conversely, asynchronous communication allows for more straightforward implementation as it does not require a shared clock, relying instead on start and stop bits to frame the data packets.

Overall, the ability to utilize RS232-based serial communication with the ATmega32/16 through USART hardware opens up numerous possibilities for interfacing with various peripherals and systems, making it an essential skill for electronics engineers and hobbyists alike.A very basic introduction to RS232 based serial communication on ATmega32/16 using the USART hardware. But before you start reading, let me warn you this post is a bit lengthy (but contains everything you need as a beginner.

so no skipping :P), so bear with it. Secondly, please keep a datasheet of ATmega32 ready with you, this is the link. I want to talk to my friend. I use my vocal cords (hardware) to transmit meaningful information (software - analogy) but using the rules of language to do it, so that he can understand it. So generalizing, for any form of communication to take place, you need hardware, software and some rules that govern the communication, right In the opening statement to this post, I referred to three terms which are very important to understand.

Most of the time, there is always a confusion regarding this terms and it is desirable to know the difference. Amongst various advantages, it helps the show-off factor. First of all, serial communication is the form of communication in which data is sent one bit at a time - across a communication channel.

The other option is parallel communication, in which, many bits are sent simultaneously across the communication channel. Needless to say, parallel communication is faster than serial communication and also easier to fathom.

But a major disadvantage is the cabling cost, which is a very important factor in the transition from parallel to serial communication over the years. RS232 (RS = Recommended Standard) is a protocol a set of standards/rules using which control signals are sent to and from the transmitter and receiver used for serial communication.

In very simple words, RS232 is a set of rules by which you can perform serial communication. That 9-pin male socket at the back of your desktop`s CPU is a serial port that carries out communication using RS232, when in use. USART (Universal Synchronous and Asynchronous Receiver and Transmitter) is hardware an integrated circuit most of the times, that helps accomplish serial communication.

USART is present inside the microcontroller begging you to use it. Serial communication is the basis of a lot of communication going around you. The communication inside your cell-phone, those noisy printers at the medicine stores, Distributed Control Systems in industries, MP3 players amongst many other systems. The protocols used vary from RS232, RS485, I2C, SPI, Token-passing etc. As for techfest aspirants, those IP-based events in which you perform image processing on some software (Matlab, OpenCV, Scilab etc.

) and are supposed to control your robot using the results of the same involve serial communication. Yes you CAN use parallel communication but that not only increases the hardware but also makes it necessary to have a desktop computer. What college kid uses a desktop ! :P So we all agree that the set of rules used is the most important thing when you want to communicate with someone.

If there are no rules, there would be no communication! Synchronous serial communication is that type of serial communication in which you supply a constant external clock and all the bits are transmitted with respect to this clock. The clock is analogous to a musical beat of any instrument, say drums. You must have noticed, in songs there is generally a beat going on and the words/lyrics start only at particular beats.

Different instruments kick in, words stop and all types of such events take place at particular beats making the song memorable. Similar is the case with synchronous serial communication. Asynchronous serial communication is that type of serial communication in which there is no need of an external clock.

Immediately, the question comes to mind how do I differentiate between messages The answer is with the help of start and stop bits. These bits are preset sequences of electronic signals that signify the start or stop