XC2269I Datasheet, PDF (46/134 Pages) Infineon Technologies AG – 16/32-Bit Single-Chip Microcontroller

XC2269I
XC2000 Family Derivatives / Premium Line
Functional Description
3.2
External Bus Controller
All external memory access operations are performed by a special on-chip External Bus
Controller (EBC). The EBC also controls access to resources connected to the on-chip
LXBus (MultiCAN and the USIC modules). The LXBus is an internal representation of
the external bus that allows access to integrated peripherals and modules in the same
way as to external components.
The EBC can be programmed either to Single Chip Mode, when no external memory is
required, or to an external bus mode with the following selections¹⁾:
• Address Bus Width with a range of 0 … 24-bit
• Data Bus Width 8-bit or 16-bit
• Bus Operation Multiplexed or Demultiplexed
The bus interface uses Port 10 and Port 2 for addresses and data. In the demultiplexed
bus modes, the lower addresses are output separately on Port 0 and Port 1. The number
of active segment address lines is selectable, restricting the external address space to
8 Mbytes … 64 Kbytes. This is required when interface lines shall be assigned to Port 2.
External CS signals (address windows plus default) can be generated and output on
Port 4 in order to save external glue logic. External modules can be directly connected
to the common address/data bus and their individual select lines.
Important timing characteristics of the external bus interface are programmable (with
registers TCONCSx/FCONCSx) to allow the user to adapt it to a wide range of different
types of memories and external peripherals.
Access to very slow memories or modules with varying access times is supported by a
special ‘Ready’ function. The active level of the control input signal is selectable.
In addition, up to four independent address windows may be defined (using registers
ADDRSELx) to control access to resources with different bus characteristics. These
address windows are arranged hierarchically where window 4 overrides window 3, and
window 2 overrides window 1. All accesses to locations not covered by these four
address windows are controlled by TCONCS0/FCONCS0. The currently active window
can generate a chip select signal.
The external bus timing is based on the rising edge of the reference clock output
CLKOUT. The external bus protocol is compatible with that of the standard C166 Family.
1) Bus modes are switched dynamically if several address windows with different mode settings are used.
Data Sheet
46
V1.3, 2014-07