ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 212

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

22. 2-wire Serial Interface
22.1
22.2
212
Features
2-wire Serial Interface Bus Definition
Atmel ATmega48PA/88PA/168PA [Preliminary]
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The 2-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
hardware 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 resolv-
ing bus contention are inherent in the TWI protocol.
Figure 22-1. TWI Bus Interconnection
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 400kHz 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
Compatible with Philips’ I
SDA
SCL
Device 1
2
C protocol
Device 2
Device 3
........
Device n
V
CC
R1
R2
9223B–AVR–09/11