Introduction
xxvi Élan™SC520 Microcontroller User’s Manual
W
The bit field is write-only. Reading this register at this bit field
does not return a meaningful value and has no side effects.
R/W
The bit field is read/write. Reading the register at this bit field
always returns the last value written. Reads have no side effects.
R/W!
The bit field is read/write with conditions. The “!” indicates that
there are side effects to using this bit. For example, reading a
bit or register might not always return the last value written. Note
that both reads and writes can have side effects. If you see a
“!”, be sure to read the bit description and programming notes.
RSV
The bit field is reserved for internal test/debug or future
expansion. This bit field should be written to 0 for normal system
operation. This bit field always returns 0 when read.
RSV!
The bit field is reserved for compatibility purposes. For example,
the bit field might be ignored during writes to maintain software
compatibility. If you see a “!”, be sure to read the bit description
and programming notes.
Reference Notation
MMCR offset 00h
ÉlanSC520 microcontroller Memory-Mapped Configuration
Region (MMCR) offset register 00h
PCI index 00h PCI indexed register 00h
Port 00h Direct-mapped I/O register 00h
RTC index 00h RTC and configuration RAM indexed register 00h
Pin Naming
{ } Pin function during hardware reset
[ ] Alternative pin function selected by software configuration
ROMCS1
An overbar indicates that the signal assumes the logic Low state
when asserted.
GPRESET
The absence of an overbar indicates that the signal assumes
the logic High state when asserted.
ads
, hold A signal name in all lowercase indicates an internal signal.
ROMCS2
–ROMCS1 Two ROM chip select signals
ROMCSx
Any of the two ROM chip select signals
Numbers
b Binary number
d
Decimal number
Decimal is the default radix
Table 0-1 Documentation Notation (Continued)
Notation Meaning
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