The speed of Serial Communication, measured in bits per second (bps). It’s the number of signal changes or transitions that occur on a communication line every second
A baud rate of 9600 bps means that 9600 bits (containing data, start/stop bits, and any parity bits) can be transmitted each second
Arduino Uno
Set the Baud Rate of the serial communication to 9600bps
Serial.begin(9600);
UART
Stands for Universal Asynchronous Receiver/Transmitter
2 wires, one wires for sending data, another wire for receiving data. The rate is determined by the Baud Rate
Unable to communicate over long distance
We have RS232 that supports communication distance that is up to 30m or RS485 that supports communication distance that is up to 1000m. RS485 also supports one-to-many communication.
Slow communication speed
UART has a maximum 11520 Baud Rate for standard applications, that means 11.25KB/s. This can be handled with SPI which has a speed up to 10MB/s.
No one-to-many communication
The CPU needs to have a dedicated pair of UART wires for each peripheral. Unable to have one pair of wires for many peripherals. This can be handled with I2C.
