TS87C51RC2 ATMEL Corporation, TS87C51RC2 Datasheet - Page 49

• Manufacturer Part Number: TS87C51RC2
• Description: High Performance 8-bit Microcontroller 32 Kbytes Otp
• Manufacturer: ATMEL Corporation

6.12. Power-Off Flag
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
the device and could be generated for example by an exit from power-down.
The power-off flag (POF) is located in PCON register (See Table 26.). POF is set by hardware when V
from 0 to its nominal voltage. The POF can be set or cleared 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.
PCON - Power Control Register (87h)
Reset Value = 00X1 0000b
Not bit addressable
Rev. C - 06 March, 2001
Bit Number
SMOD1
7
6
5
4
3
2
1
0
7
Mnemonic
SMOD1
SMOD0
POF
GF1
GF0
IDL
Bit
SMOD0
PD
-
6
Serial port Mode bit 1
Serial port Mode bit 0
Reserved
Power-Off Flag
General purpose Flag
General purpose Flag
Power-Down mode bit
Idle mode bit
Set to select double baud rate in mode 1, 2 or 3.
Clear to select SM0 bit in SCON register.
Set to to select FE bit in SCON register.
The value read from this bit is indeterminate. Do not set this bit.
Clear to recognize next reset type.
Set by hardware when V
Cleared by user for general purpose usage.
Set by user for general purpose usage.
Cleared by user for general purpose usage.
Set by user for general purpose usage.
Cleared by hardware when reset occurs.
Set to enter power-down mode.
Clear by hardware when interrupt or reset occurs.
Set to enter idle mode.
5
-
CC
Table 26. PCON Register
switch-on. A warm start reset occurs while V
POF
CC
4
rises from 0 to its nominal voltage. Can also be set by software.
GF1
3
Description
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
GF0
2
TS80C51RA2/RD2
PD
1
CC
is still applied to
IDL
CC
0
rises
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