DS87C530_05 Datasheet, PDF (21/47 Pages) Dallas Semiconductor – EPROM/ROM Microcontrollers with Real-Time Clock

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