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I2C vs RS485-Difference between I2C and RS485

This page compares I2C vs RS485 and mentions difference between I2C and RS485. It provides links for further study on I2C and RS485 interface protocols.

I2C Protocol


It is a communication protocol which allows one or more masters to communicate with multiple slave devices on ICs. Like SPI it is used for short distance communication within single device. It requires only two signal lines to exchange data.
Refer difference between I2C vs SPI vs UART.

RS485 Protocol


The RS485 is predecessor to RS422 interface. It is a multidrop and balanced interface which uses half as well as full duplex communication modes. In RS485 single device can control upto 32 devices. Binary data of 1 is indicated when B>A by value of 1.5V (max.) and data of 0 is indicated when A>B by value of 1.5V (max.). Here A and B are two wires used in RS485 for transmit and receive.
Refer RS485 Interface and difference between RS485 vs RS232.

Specifications I2C RS485
Distance It is short distance protocol. It is long distance protocol. Covers 50 feet (@10 Mbps) to 4000 feet (@100 Kbps).
Clock It sends and receives the data with respect to clock signal. It sends and receives the data without clock signal.
Speed Slower compare to RS485 Faster compare to I2C
Addressing It increments address for data storage automatically. It assigns address manually for data storage every time.
Multi-master communication Supported Such feature is not available rather RS485 works in single transmitter to multiple receiver mode.
Pin Designations It uses SDA (Serial Data) and SCL (Serial Clock) lines. It uses two transmit (TxD+, TxD-) and two receive (RxD+ and RxD-) lines.
Data rate I2C supports 100 kbps, 400 kbps, 3.4 Mbps. Some variants also supports 10 Kbps and 1 Mbps. 100 Kbps to 10 Mbps
Type of communication Synchronous Asynchronous

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