ATXMEGA64A1 datasheet(36/99 Pages) ATMEL

36 / 99 page

8067I–AVR–04/09

XMEGA A1

19. TWI - Two-Wire Interface

19.1

Features

• Four Identical TWI peripherals

• Simple yet Powerful and Flexible Communication Interface

• Both Master and Slave Operation Supported

• Device can Operate as Transmitter or Receiver

• 7-bit Address Space Allows up to 128 Different Slave Addresses

• Multi-master Arbitration Support

• Up to 400 kHz Data Transfer Speed

• Slew-rate Limited Output Drivers

• Noise Suppression Circuitry Rejects Spikes on Bus Lines

• Fully Programmable Slave Address with General Call Support

• Address Recognition Causes Wake-up when in Sleep Mode

• I2C and System Management Bus (SMBus) compatible

19.2

Overview

The Two-Wire Interface (TWI) is a bi-directional wired-AND bus with only two lines, the clock

(SCL) line and the data (SDA) line. The protocol makes it possible to interconnect up to 128 indi-

vidually addressable devices. Since it is a multi-master bus, one or more devices capable of

taking control of the bus can be connected.

The only external hardware needed to implement the bus is a single pull-up resistor for each of

the TWI bus lines. Mechanisms for resolving bus contention are inherent in the TWI protocol.

PORTC, PORTD, PORTE, and PORTF each has one TWI. Notation of these peripherals are

TWIC, TWID, TWIE, and TWIF, respectively.

ATXMEGA64A1 Datasheet(PDF) 36 Page - ATMEL Corporation