4.1 Basic Concepts of Serial Communication
Serial communication is a commonly used communication method, which refers to data transmission between devices through a Serial Interface. There are several basic concepts of serial communication:
4.1.1 Serial Communication
Serial communication refers to the transmission of data bit by bit, transmitting only one bit at a time. Compared to parallel communication, serial communication, although slower, has fewer pin and cable requirements, reducing hardware costs.
4.1.2 Communication Protocol
A communication protocol is a set of rules that defines how two parties exchange information. There are various protocols for serial communication, such as UART (Universal Asynchronous Receiver-Transmitter), SPI (Serial Peripheral Interface), and I2C (Inter-Integrated Circuit). Different protocols have different characteristics such as transmission speed, communication distance, and the number of connected devices.
4.1.3 UART Communication
UART is a commonly used serial communication protocol. It uses asynchronous communication, which does not require a clock signal for synchronization. UART communication has two signal lines: TX (transmit) and RX (receive). Data is sent on the TX line and received on the RX line. UART communication can achieve full-duplex communication, meaning that data can be sent and received simultaneously at the same time.
4.1.4 Baud Rate
The baud rate is the unit of measurement for the speed of data transmission in serial communication, representing the number of symbols transmitted per second (unit: bps, bits per second). Both parties in communication need to use the same baud rate to ensure the accuracy of data transmission. Common baud rates include 9600, 19200, 38400, 57600, and 115200 bps, etc.
4.1.5 Parity Bit
To ensure the accuracy of data in serial communication, a parity bit can be used for error detection. The parity bit can be odd parity, even parity, or no parity. Odd and even parity calculate the number of 1s in the data bits so that the total number of data bits and the parity bit is odd or even. No parity means no error detection is performed.
4.1.6 Start and Stop Bits
Start and stop bits are used to indicate the beginning and end of a data frame. In UART communication, the start bit is usually low, indicating the start of the data frame; the stop bit is usually high, indicating the end of the data frame. Start and stop bits help the receiving end correctly parse the data frame.
Through these basic concepts, one can understand the basic principles and characteristics of serial communication. Serial communication is widely used for data transmission between various devices, such as microcontrollers, sensors, communication modules, etc. In practical applications, serial communication can achieve data exchange, remote control, and monitoring functions between devices.
4.1.7 Communication Modes
There are several common communication modes for serial communication:
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Simplex Communication: Data can only be transmitted in one direction, meaning the sender can only send data, and the receiver can only receive data.
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Half-Duplex Communication: Data can be transmitted in both directions, but only one direction can transmit data at a time. Both parties need to wait for the other to complete data transmission before starting their own data transmission.
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Full-Duplex Communication: Data can be transmitted simultaneously in both directions. Both parties can send and receive data at any time without waiting for the other party.
4.1.8 Level Shifting
Since different devices may use different voltage standards, such as 5V or 3.3V, level shifting may be required in serial communication. A level shifter can enable communication between devices of different voltages, preventing device damage due to voltage mismatches.
4.1.9 Programming Implementation
In programming, serial communication is usually implemented through software libraries or hardware modules. For example, on the Arduino platform, the Serial library can be used for serial communication. The Serial library provides common serial communication functions, such as setting baud rates, sending, and receiving data. Through programming, control and data processing of serial communication can be achieved.
By understanding the basic concepts and principles of serial communication, one can better apply them in practical projects. The flexibility and scalability of serial communication make it an ideal choice for communication between various electronic systems and devices.
