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IDT EJTAG System
EJTAG Test Access Port
79RC32438 User Reference Manual
20 - 68
November 4, 2002
Notes
PrRst
16
Controls the processor reset with imple-
mentation-dependent behavior:
0:
No processor reset applied
1:
Processor reset applied
The PrRst bit might not have any effect.
There is no inherent indication of an effec-
tive PrRst, so the user must consult system
documentation.
If a reset occurs on PrRst, then all parts of
the system are reset. It is not allowed for
only some device to be reset.
When this bit is changed then it is guaran-
teed that the new value has taken effect
when it can be read back here. This hand-
shake mechanism ensures that the setting
from the JTAG_TCK clock domain takes
effect in the processor clock domain and in
peripherals.
However, because a processor reset
clears this bit, then the effect of setting it
can be that the bit is cleared when the
reset takes effect. In this case, the Rocc bit
should be observed to detect that the reset
took effect.
This bit is read-only (R) and reads as zero
if not implemented.
R/W
0
Optional
ProbEn
15
Controls whether the probe handles
accesses to dmseg through servicing of
processors accesses:
0:
Probe does not service processors
accesses
1:
Probe will service processor accesses
The ProbEn bit is reflected as a read-only
bit in the Debug Control Register (DCR) bit
0.
When this bit is changed, then it is guaran-
teed that the new value has taken effect in
the DCR when it can be read back here.
This handshake mechanism ensures that
the setting from the JTAG_TCK clock
domain takes effect in the processor clock
domain.
However, a change of the ProbEn prior to
setting the EjtagBrk bit will be effective for
the debug handler.
Not all combinations of ProbEn and Prob-
Trap are allowed, see
section “Combina-
tions of ProbTrap and ProbEn” on page 20-
70.
R/W
See section
“EJTAG-
BOOT Indica-
tion
Determines
Reset Value
of EjtagBrk,
ProbTrap and
ProbEn” on
page 20-70
Required
Fields
Description
Read/
Write
Reset
State
Compli-
ance
Name
Bit
Table 20.48 EJTAG Control Register Field Description (Part 3 of 4)