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Data Sheet
363
Rev. 1.2, 2006-01-26
QuadFALCTM
PEF 22554 E
E1 Registers
Table 94
Registers Access Types
Mode
Symbol Description Hardware (HW)
Description Software (SW)
Basic Access Types
read/write
rw
Register is used as input for the HW
Register is read and writable by SW
read/write
virtual
rwv
Physically, there is no new register in
the generated register file. The real
readable and writable register resides
in the attached hardware.
Register is read and writable by SW (same
as rw type register)
read
r
Register is written by HW (register
between input and output -> one cycle
delay)
Value written by SW is ignored by HW; that
is, SW may write any value to this field
without affecting HW behavior
read only
ro
Same as r type register
read virtual
rv
Physically, there is no new register in
the generated register file. The real
readable register resides in the
attached hardware.
Value written by SW is ignored by HW; that
is, SW may write any value to this field
without affecting HW behavior (same as r
type register)
write
w
Register is written by software and
affects hardware behavior with every
write by software.
Register is writable by SW. When read, the
register does not return the value that has
been written previously, but some constant
value instead.
write virtual
wv
Physically, there is no new register in
the generated register file. The real
writable register resides in the attached
hardware.
Register is writable by SW (same as w type
register)
read/write
hardware
affected
rwh
Register can be modified by hardware
and software at the same time. A
priority scheme decides, how the value
changes with simultaneous writes by
hardware and software.
Register can be modified by HW and SW,
but the priority SW versus HW has to be
specified.
SW can read the register.
Special Access Types
Latch high,
self clearing
lhsc
Latch high signal at high level, clear on
read
SW can read the register
Latch low,
self clearing
llsc
Latch high signal at low-level, clear on
read
SW can read the register
Latch high,
mask clearing
lhmk
Latch high signal at high level, register
cleared with written mask
SW can read the register, with write mask
the register can be cleared (1 clears)
Latch low,
mask clearing
llmk
Latch high signal at low-level, register
cleared on read
SW can read the register, with write mask
the register can be cleared (1 clears)
Interrupt high,
self clearing
ihsc
Differentiate the input signal (low-
>high) register cleared on read
SW can read the register
Interrupt low,
self clearing
ilsc
Differentiate the input signal (high-
>low) register cleared on read
SW can read the register
Interrupt high,
mask clearing
ihmk
Differentiate the input signal (high-
>low) register cleared with written mask
SW can read the register, with write mask
the register can be cleared
Interrupt low,
mask clearing
ilmk
Differentiate the input signal (low-
>high) register cleared with written
mask
SW can read the register, with write mask
the register can be cleared