C161RI_1 Datasheet, PDF (239/317 Pages) Siemens Semiconductor Group – 16-Bit CMOS Single-Chip Microcontroller

The I²C-Bus Module
C161RI
17.2 The Physical I²C-Bus Interface
Communication via the I²C Bus uses two bidirectional lines, the serial data line SDA and the serial
clock line SCL. These two generic interface lines can each be connected to a number of IO port
lines of the C161RI (see figure below). These connections can be established and released under
software control.
I²C
Module
Generic data line
Generic clock line
SDAx
SDA0
SCL0
SCLx
Figure 17-3
I²C-Bus Line Connections
This mechanism allows a number of configurations of the physical I²C-bus interface:
Channel switching: The I²C module can be connected to a specific pair of pins (e.g. SDA0 and
SCL0) which then forms a separate I²C channel to the external system. The channel can be
dynamically switched by connecting the module to another pair of pins (e.g. SDA1 and SCL1). This
establishes physically separate interface channels.
Broadcasting: Connecting the module to more than one pair of pins (e.g. SDA0/1 and SCL0/1)
allows the transmission of messages over multiple physical channels at the same time. Please note
that this configuration is critical when the C161RI is a slave or receives data.
Note: Never change the physical bus interface configuration while a transfer is in progress.
Semiconductor Group
17-4
1998-05-01