Datasheet
685
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
34. Two-wire Interface (TWI)
34.1 Description
The Atmel Two-wire Interface (TWI) interconnects components on a unique two-wire bus, made up of one clock line and
one data line with speeds of up to 400 Kbits per second, based on a byte-oriented transfer format. It can be used with
any Atmel Two-wire Interface bus Serial EEPROM and I²C compatible device such as Real Time Clock (RTC), Dot
Matrix/Graphic LCD Controllers and Temperature Sensor, to name but a few. The TWI is programmable as a master or a
slave with sequential or single-byte access. Multiple master capability is supported.
Arbitration of the bus is performed internally and puts the TWI in slave mode automatically if the bus arbitration is lost.
A configurable baud rate generator permits the output data rate to be adapted to a wide range of core clock frequencies.
Table 34-1 lists the compatibility level of the Atmel Two-wire Interface in Master Mode and a full I
2
C compatible device.
Note: 1. START + b000000001 + Ack + Sr
34.2 Embedded Characteristics
2 TWIs
Compatible with Atmel Two-wire Interface Serial Memory and I²C Compatible Devices
(1)
One, Two or Three Bytes for Slave Address
Sequential Read-write Operations
Master, Multi-master and Slave Mode Operation
Bit Rate: Up to 400 Kbit/s
General Call Supported in Slave mode
SMBUS Quick Command Supported in Master Mode
Connection to Peripheral DMA Controller (PDC) Channel Capabilities Optimizes Data Transfers
One Channel for the Receiver, One Channel for the Transmitter
Note: 1. See Table 34-1 for details on compatibility with I²C Standard.
Table 34-1. Atmel TWI compatibility with I
2
C Standard
I
2
C Standard Atmel TWI
Standard Mode Speed (100 kHz) Supported
Fast Mode Speed (400 kHz) Supported
7 or 10 bits Slave Addressing Supported
START BYTE
(1)
Not Supported
Repeated Start (Sr) Condition Supported
ACK and NACK Management Supported
Slope control and input filtering (Fast mode) Not Supported
Clock stretching Supported
Multi Master Capability Supported