Rainbow Electronics T89C51RD2 - Manual (Page 36)

Rev. F - 15 February, 2001 36
T89C51RD2
Table 16. PCON Register
PCON - Power Control Register (87h)
Reset Value = 00X1 0000b
Not bit addressable
Power-off flag reset value will be 1 only after a power on (cold reset). A warm reset doesn’t affect the value of this bit.
7 6 5 4 3 2 1 0
SMOD1 SMOD0 - POF GF1 GF0 PD IDL
Bit
Number
Bit
Mnemonic
Description
7 SMOD1
Serial port Mode bit 1
Set to select double baud rate in mode 1, 2 or 3.
6 SMOD0
Serial port Mode bit 0
Clear to select SM0 bit in SCON register.
Set to to select FE bit in SCON register.
5 -
Reserved
The value read from this bit is indeterminate. Do not set this bit.
4 POF
Power-Off Flag
Clear to recognize next reset type.
Set by hardware when VCC rises from 0 to its nominal voltage. Can also be set by software.
3 GF1
General purpose Flag
Cleared by user for general purpose usage.
Set by user for general purpose usage.
2 GF0
General purpose Flag
Cleared by user for general purpose usage.
Set by user for general purpose usage.
1 PD
Power-Down mode bit
Cleared by hardware when reset occurs.
Set to enter power-down mode.
0 IDL
Idle mode bit
Clear by hardware when interrupt or reset occurs.
Set to enter idle mode.