Serial Communication Basics

Study Notes

Serial communication transmits data one bit at a time over a single channel.
Common for communication between computers and peripherals.
Data is sent sequentially, contrasting with parallel communication where multiple bits are transmitted simultaneously.
Parallel data must be "shifted" to be transmitted serially.

Asynchronous: Data is sent without a clock signal, using start and stop bits to indicate the beginning and end of a data packet.
Synchronous: A clock signal synchronizes the sender and receiver, allowing for faster data transfer.

Bit rate: measures the number of bits transmitted per second (bps).
Baud rate: measures the number of signal changes or symbols transmitted per second, which may represent one or more bits.

Bit Error: a single bit is incorrectly transmitted.
Framing Error: the receiver fails to detect the correct start and stop bits in the data frame.
Overrun Error: a new byte overwrites the previous byte before the receiver completes reading the previous byte.
Parity Error: the number of 1s in a data frame does not match the expected parity.
Timeout Error: no data is received within an expected time frame.
Checksum Error: used to check errors in blocks of data.

RS-232: Widely used for connecting computers and peripherals, typically ranges from 300 bps to 115,200 bps and effective up to 15 meters.
RS-485: Used in industrial environments for its robustness over long distances, up to 10 Mbps and 1,200 meters.
I2C (Inter-Integrated Circuit): Primarily used for short-distance communication between chips on a circuit board, supporting multiple devices and up to 3.4 MHz speeds.
SPI (Serial Peripheral Interface): Primarily used for short-distance communication between microcontrollers and peripherals, supporting full-duplex communication and speeds ranging from a few Mbps to tens of Mbps.

Developed to define the electrical characteristics and timing of signals and the physical interface for serial data communication.
Introduced in the 1960s by the Electronic Industries Alliance (EIA).
Uses voltage levels to represent bits and includes start/stop bits for framing.
Characterized by its use of a 25-pin connector (DB-25) or a 9-pin connector (DB-9).