ATmega32A datasheet(176/352 Pages) ATMEL

176 / 352 page

176

8155B–AVR–07/09

ATmega32A

20. Two-wire Serial Interface

20.1

Features

• Simple Yet Powerful and Flexible Communication Interface, Only Two Bus Lines Needed

• 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 AVR is in Sleep Mode

20.2

Two-wire Serial Interface Bus Definition

The Two-wire Serial Interface (TWI) is ideally suited for typical microcontroller applications. The

TWI protocol allows the systems designer to interconnect up to 128 different devices using only

two bi-directional bus lines, one for clock (SCL) and one for data (SDA). The only external hard-

ware needed to implement the bus is a single pull-up resistor for each of the TWI bus lines. All

devices connected to the bus have individual addresses, and mechanisms for resolving bus

contention are inherent in the TWI protocol.

Figure 20-1. TWI Bus Interconnection

Device 1

Device 2

Device 3

Device n

SDA

SCL

........

ATmega32A Datasheet(PDF) 176 Page - ATMEL Corporation