DS87C520 Maxim, DS87C520 Datasheet - Page 18

• Manufacturer Part Number: DS87C520
• Description: The DS87C520/DS83C520 EPROM/ROM high-speed microcontrollers are fast 8051-compatible microcontrollers
• Manufacturer: Maxim

Table 6. PMM Control and Status Bit Summary
CD1, CD0
XTOFF
XT/RG
RGMD
SPTA1
SPRA1
SPTA0
SPRA0
XTUP
SWB
BIT
HIP
PIP
LIP
LOCATION
STATUS.7
STATUS.6
STATUS.5
STATUS.4
STATUS.3
STATUS.2
STATUS.1
STATUS.0
PMR.7,
EXIF.3
EXIF.2
PMR.6
PMR.5
PMR.3
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.
Control. CD1, 0 = 01, 4 clocks; CS1, 0 = 10, PMM1;
CD1, 0 = 11, PMM2.
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.
DS87C520/DS83C520 EPROM/ROM High-Speed Microcontrollers
FUNCTION
18 of 43
.
RESET
0, 1
X
0
0
0
0
0
0
1
0
0
0
0
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
WRITE ACCESS