SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 28

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

C164CM/C164SM
Derivatives
Architectural Overview
External Bus Interface
To meet the needs of designs where more memory is required than is provided on chip,
up to 64 KBytes of external RAM and/or ROM can be connected to the C164CM
microcontroller via its external bus interface. The integrated External Bus Controller
(EBC) allows very flexible access to external memory and/or peripheral resources. For
up to five address areas the bus mode (multiplexed / demultiplexed), the data bus width
(8-bit/16-bit) and even the length of a bus cycle (waitstates, signal delays) can be
selected independently. This allows access to a variety of memory and peripheral
components directly and with maximum efficiency. If the device does not run in Single
Chip Mode, where no external memory is required, the EBC can control external
accesses in one of the following external access modes:
• 16-bit Addresses, 16-bit Data, Demultiplexed
• 16-bit Addresses, 8-bit Data, Demultiplexed
• 16-bit Addresses, 16-bit Data, Multiplexed
• 11-bit Addresses, 8-bit Data, Multiplexed
The demultiplexed bus modes use PORT1 for addresses and PORT0 for data input/
output. The multiplexed bus modes use PORT0 for both addresses and data input/
output.
Important timing characteristics of the external bus interface (waitstates, ALE length, and
Read/Write Delay) have been made programmable to allow the user select a wide range
of different types of memories and/or peripherals.
The on-chip XBUS is an internal representation of the external bus. It allows access to
integrated application-specific peripherals/modules in the same way as external
components. It provides a defined interface for these customized peripherals. The on-
chip CAN-Module is an example for these X-Peripherals.
Even though the C164CM supports all the bus modes described above, many
applications will use it in Single-Chip mode. Due to the very compact package many
alternate I/O signals use PORT0 and PORT1, so utilizing the full bus interface conflicts
with a number of peripheral functions.
A very good compromise is 8-bit multiplexed mode, where only 11 pins of PORT0 are
occupied by the bus interface. This allows control of external peripherals while providing
most I/O functions at the same time.
User’s Manual
2-11
V1.0, 2002-02