Two-wire interface (twi), 1 description – Rainbow Electronics AT91CAP9S250A User Manual
Page 483
483
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
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. 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.
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
Table 34-1.
Atmel TWI Compatibility with I
2
C Standard
I2C Standard
Atmel TWI
Standard Mode Speed (100 KHz)
Supported
Fast Mode Speed (400 KHz)
Supported
7 or 10 bits Slave Addressing
Supported
START BYTE
Not Supported
Repeated Start (Sr) Condition
Supported
ACK and NACK Management
Supported
Slope control and input filtering (Fast mode)
Not Supported
Clock stretching
Supported