42.1 Description

The Two-wire Interface (TWIHS) interconnects components on a unique two-wire bus, made up of one clock line and one data line with speeds of up to 400 kbit/s in Fast mode and up to 3.4 Mbit/s in High-speed Client mode only, based on a byte-oriented transfer format. It can be used with any Two-wire Interface bus Serial EEPROM and I²C-compatible devices, such as a Real-Time Clock (RTC), Dot Matrix/Graphic LCD Controller and temperature sensor. The TWIHS is programmable as a Host or a Client with sequential or single-byte access. Multiple Host capability is supported.

A configurable baud rate generator permits the output data rate to be adapted to a wide range of core clock frequencies.

The table below lists the compatibility level of the Two-wire Interface in Host mode and a full I2C compatible device.

Table 42-1. TWI Compatibility with I2C Standard
I2C Standard TWI
Standard Mode Speed (100 kHz) Supported
Fast Mode Speed (400 kHz) Supported
High-speed Mode (Client only, 3.4 MHz) Supported
7- or 10-bit(1) Client Addressing Supported
START Byte(2) Not Supported
Repeated Start (Sr) Condition Supported
ACK and NACK Management Supported
Input Filtering Supported
Slope Control Not Supported
Clock Stretching Supported
Multi Host Capability Supported
Note:
  1. 10-bit support in Host mode only.
  2. START + b000000001 + Ack + Sr.