DS87C530_1 Datasheet, PDF (19/44 Pages) Dallas Semiconductor – EPROM/ROM Micro with Real Time Clock

PMM CONTROL AND STATUS BIT SUMMARY Table 7
BIT NAME LOCATION
FUNCTION
RESET
XT/ RG
EXIF.3
RGMD
EXIF.2
Control. XT/ RG =1, runs from crystal X
or external clock; XT/ RG =0, runs
from internal ring oscillator.
Status. RGMD=1, CPU clock = ring;
0
RGMD=0, CPU clock = crystal.
CD1, CD0 PMR7,
Control. CD1,0=01, 4 clocks;
0, 1
PMR.6
CS1,0=10, PMM1; CD1,0=11,
PMM2.
SWB
PMR.5
Control. SWB=1, hardware invokes
0
switchback to 4 clocks, SWB=0, no
hardware switchback.
XTOFF
PMR.3
Control. Disables crystal operation
0
after ring is selected.
PIP
HIP
LIP
XTUP
SPTA1
SPRA1
SPTA0
SPRA0
STATUS.7 ^{Status. 1 indicates a power-fail}
0
interrupt in service.
STATUS.6 ^{Status. 1 indicates high priority}
0
interrupt in service.
STATUS.5 ^{Status. 1 indicates low priority}
0
interrupt in service.
STATUS.4 ^{Status. 1 indicates that the crystal has}
1
stabilized.
STATUS.3 ^{Status. Serial transmission on serial}
0
port 1.
STATUS.2 ^{Status. Serial word reception on serial} 0
port 1.
STATUS.1 ^{Status. Serial transmission on serial}
0
port 0.
STATUS.0 ^{Status. Serial word reception on serial} 0
port 0.
DS87C530/DS83C530
WRITE ACCESS
0 to 1 only when
XTUP=1 and
XTOFF=0
None
Write CD1,0=10 or
11 only from
CD1,0=01
Unrestricted
1 only when
XT/ RG =0
None
None
None
None
None
None
None
None
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