Datasheet

42
XMEGA E5 [DATASHEET]
Atmel-8153J–AVR-ATxmega8E5-ATxmega16E5-ATxmega32E5_Datasheet–11/2014
22. TWI – Two-Wire Interface
22.1 Features
 One two-wire interface
 Phillips I
2
C compatible
 System Management Bus (SMBus) compatible
 Bus master and slave operation supported
 Slave operation
 Single bus master operation
 Bus master in multi-master bus environment
 Multi-master arbitration
 Bridge mode with independent and simultaneous master and slave operation
 Flexible slave address match functions
 7-bit and general call address recognition in hardware
 10-bit addressing supported
 Address mask register for dual address match or address range masking
 Optional software address recognition for unlimited number of addresses
 Slave can operate in all sleep modes, including power-down
 Slave address match can wake device from all sleep modes
 100kHz, 400kHz, and 1MHz bus frequency support
 Slew-rate limited output drivers
 Input filter for bus noise and spike suppression
 Support arbitration between start/repeated start and data bit (SMBus)
 Slave arbitration allows support for address resolve protocol (ARP) (SMBus)
 Supports SMBUS Layer 1 timeouts
 Configurable timeout values
 Independent timeout counters in master and slave (Bridge mode support)
22.2 Overview
The two-wire interface (TWI) is a bidirectional, two-wire communication interface. It is I
2
C and System Management Bus
(SMBus) compatible. The only external hardware needed to implement the bus is one pull-up resistor on each bus line.
A device connected to the bus must act as a master or a slave. One bus can have many slaves and one or several
masters that can take control of the bus.
The TWI module supports master and slave functionality. The master and slave functionality are separated from each
other, and can be enabled and operate simultaneously and separately. The master module supports multi-master bus
operation and arbitration. It contains the baud rate generator. Quick command and smart mode can be enabled to auto-
trigger operations and reduce software complexity. The master can support 100kHz, 400kHz, and 1MHz bus frequency.
The slave module implements 7-bit address match and general address call recognition in hardware. 10-bit addressing is
also supported. A dedicated address mask register can act as a second address match register or as a register for
address range masking. The slave continues to operate in all sleep modes, including power-down mode. This enables
the slave to wake up the device from all sleep modes on TWI address match. It is possible to disable the address
matching to let this be handled in software instead. By using the bridge option, the slave can be mapped to different pin
locations. The master and slave can support 100kHz, 400kHz, and 1MHz bus frequency.
The TWI module will detect START and STOP conditions, bus collisions, and bus errors. Arbitration lost, errors, collision,
and clock hold on the bus are also detected and indicated in separate status flags available in both master and slave
modes.