C161RI_1 Datasheet, PDF (159/317 Pages) Siemens Semiconductor Group – 16-Bit CMOS Single-Chip Microcontroller

The External Bus Interface
C161RI
9.6 The XBUS Interface
The C161RI provides an on-chip interface (the XBUS interface), which allows to connect integrated
customer/application specific peripherals to the standard controller core. The XBUS is an internal
representation of the external bus interface, i.e. it is operated in the same way.
For each peripheral on the XBUS (X-Peripheral) there is a separate address window controlled by
a hardwired register pair similar to registers BUSCON and ADDRSEL. As an interface to a
peripheral in many cases is represented by just a few registers, the registers partly select smaller
address windows than the standard ADDRSEL registers. As the register pairs control integrated
peripherals rather than externally connected ones, they are fixed by mask programming rather than
being user programmable.
X-Peripheral accesses provide the same choices as external accesses, so these peripherals may
be bytewide or wordwide, with or without a separate address bus. Interrupt nodes are provided for
X-Peripherals to be integrated.
Note: If you plan to develop a peripheral of your own to be integrated into a C161RI device to create
a customer specific version, please ask for the specification of the XBUS interface and for
further support.
Semiconductor Group
9-26
1998-06-01