TC1796
Functional Description
3.5
External Bus Unit
The External Bus Unit (EBU) of the TC1796 is the units that controls the transactions
between external memories or peripheral units with the internal memories and peripheral
units. The EBU is a part of the PMU and communicates with CPU and PMI via the
Program Local Memory Bus. This configuration allows to get fast access times especially
when using external burst FLASH memory devices.
32
Data
Bus
Data Path
Control
Asynchronous
Access
State Machine
Control
Lines
64
32
Burst Access
State Machine
Program
Local
Memory
PLMB
Data
64
Region
Selection
Bus
Arbitration
Signals
External Bus
Arbitration
PLMB
Address
24
Address
Bus
Address Path
Control
External Bus Unit EBU
MCB05713
Figure 4
EBU Block Diagram
The following features are supported by the EBU:
•
•
64-bit internal Program Local Memory Bus (PLMB) interface
32-bit external demultiplexed bus interface
– Asynchronous read/write accesses support Intel-style and Motorola-style interface
signals
– Synchronous burst FLASH memory read
– Five programmable regions associated each to one chip select output
– Flexibly programmable access parameters for each chip select region
– Little-endian and Big-endian support
– Programmable wait state control
Scalable external bus frequency
•
– Derived from PLMB frequency (fCPU) divided by 1, 2, 3, or 4
– Max. 75 MHz
Data Sheet
41
V1.0, 2008-04
INFINEON [ Infineon ]
