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1. Communication Basics
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Based on transmission direction, communication can be divided into simplex, half-duplex, and full-duplex communication. -
Simplex communication: Data can only be sent from the sender to the receiver, and cannot be sent back. -
Half-duplex communication: Data can be transmitted back and forth between the sender and receiver, but cannot be sent simultaneously. -
Full-duplex communication: Data can be transmitted simultaneously between the sender and receiver.
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Baud rate (in bps): The rate at which binary data bits are transmitted, indicating the number of binary bits transmitted per second. For example: 256bps means 256 data bits can be sent per second. -
Asynchronous communication: A communication method where the sender sends data without waiting for a response from the receiver before sending the next data packet—non-blocking. -
Synchronous communication: A communication method where the sender sends the next data packet only after receiving a response from the receiver—blocking.
2. UART Communication Principles
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UART (Universal Asynchronous Receiver Transmitter) is a universal serial, asynchronous communication bus,which has two data lines and one ground line, supporting full-duplex asynchronous communication. It is commonly used for communication between microcontrollers and peripheral devices.
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UART sends 8-bit data from low to high in sequence, and actually sends and receives 10 bits of data at a time. Note: The baud rates of the sender and receiver must match. When the bus is idle, the line remains high; before sending data, a 0 is sent first to change the bus from high to low, signaling the data receiver to prepare. It sends 8 bits of data sequentially from low to high. After the 8 bits of data are transmitted, a 1 is sent to return the bus to a high state. If new data is to be sent, the start bit needs to be sent again, repeating the above process. RS-232 and USB to serial are often used for board-to-board communication.
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