TS80C51RA2 Atmel Corporation, TS80C51RA2 Datasheet - Page 48

• Manufacturer Part Number: TS80C51RA2
• Description: High Performance 8-bit Microcontroller
• Manufacturer: Atmel Corporation

Power-Off Flag
48
TS8xC51Rx2
The power-off flag allows the user to distinguish between a “cold start” reset and a
“warm start” reset.
A cold start reset is the one induced by V
V
power-down.
The power-off flag (POF) is located in PCON register (See Table 28). POF is set by
hardware when V
by software allowing the user to determine the type of reset.
The POF value is only relevant with a Vcc range from 4.5V to 5.5V. For lower Vcc value,
reading POF bit will return indeterminate value.
Table 28. PCON Register
PCON - Power Control Register (87h)
Reset Value = 00X1 0000b
Not bit addressable
Number
CC
SMOD1
Bit
7
6
5
4
3
2
1
0
is still applied to the device and could be generated for example by an exit from
7
Mnemonic
SMOD0
SMOD1
SMOD0
POF
GF1
GF0
Bit
IDL
6
PD
-
CC
rises from 0 to its nominal voltage. The POF can be set or cleared
Description
Serial port Mode bit 1
Set to select double baud rate in mode 1, 2 or 3.
Serial port Mode bit 0
Clear to select SM0 bit in SCON register.
Set to to select FE bit in SCON register.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Power-Off Flag
Clear to recognize next reset type.
Set by hardware when V
by software.
General purpose Flag
Cleared by user for general purpose usage.
Set by user for general purpose usage.
General purpose Flag
Cleared by user for general purpose usage.
Set by user for general purpose usage.
Power-Down mode bit
Cleared by hardware when reset occurs.
Set to enter power-down mode.
Idle mode bit
Clear by hardware when interrupt or reset occurs.
Set to enter idle mode.
5
-
POF
4
CC
CC
switch-on. A warm start reset occurs while
rises from 0 to its nominal voltage. Can also be set
GF1
3
GF0
2
PD
1
4188A–8051–10/02
IDL
0