
75
AT89C51ID2
4289C–8051–11/05
Registers
Table 58. PCON Register
PCON (S87:h) Power configuration Register
Reset Value= XXXX 0000b
76
543
210
--
-
POF
GF1
GF0
PD
IDL
Bit
Number
Bit
Mnemonic
Description
7-5
-
Reserved
The value read from these bits is indeterminate. Do not set these bits.
4POF
Power-Off Flag
Cleared to recognize next reset type.
Set by hardware when VCC rises from 0 to its nominal voltage. Can also be set
by software.
3GF1
General Purpose flag 1
One use is to indicate whether an interrupt occurred during normal operation or
during Idle mode.
2GF0
General Purpose flag 0
One use is to indicate whether an interrupt occurred during normal operation or
during Idle mode.
1PD
Power-Down Mode bit
Cleared by hardware when an interrupt or reset occurs.
Set to activate the Power-Down mode.
If IDL and PD are both set, PD takes precedence.
0IDL
Idle Mode bit
Cleared by hardware when an interrupt or reset occurs.
Set to activate the Idle mode.
If IDL and PD are both set, PD takes precedence.