at91sam9g20-cu ATMEL Corporation, at91sam9g20-cu Datasheet - Page 415

• Manufacturer Part Number: at91sam9g20-cu
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

31. Two-wire Interface (TWI)
31.1
31.2
6384B–ATARM–15-Dec-08
Overview
List of Abbreviations
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. Arbitra-
tion 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.
Below,
a full I2C compatible device.
Table 31-1.
Note:
Table 31-2.
I2C Standard
Standard Mode Speed (100 KHz)
Fast Mode Speed (400 KHz)
7 or 10 bits Slave Addressing
START BYTE
Repeated Start (Sr) Condition
ACK and NACK Management
Slope control and input filtering (Fast mode)
Clock stretching
Abbreviation
TWI
A
NA
P
S
Sr
SADR
Table 31-1
1. START + b000000001 + Ack + Sr
(1)
Atmel TWI compatibility with i2C Standard
Abbreviations
lists the compatibility level of the Atmel Two-wire Interface in Master Mode and
Description
Two-wire Interface
Acknowledge
Non Acknowledge
Stop
Start
Repeated Start
Slave Address
AT91SAM9G20 Preliminary
Atmel TWI
Supported
Supported
Supported
Not Supported
Supported
Supported
Not Supported
Supported
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