POWER-DOWN
Mode
An instruction setting
PCON.1
causes the device go into the
POWER-DOWN
mode. In the
POWER-DOWN
mode, the on-chip oscillator is stopped. The contents of on-chip RAM and
SFRs are maintained.
The power-down mode can be woken-up by either pin RST event or interrupt from INT0 or
INT1. When it is woken-up by RST, the program will execute from the address 0x0000. Be
careful to keep RST pin active for at least 10ms in order for a stable clock. If it is woken-up
from pin INT0 or INT1, the CPU will rework through jumping to related interrupt service routine.
Before the CPU rework, the clock is blocked and counted until 32768 in order for de-bouncing
the unstable clock. To use INT0/INT1 wake-up, interrupt-related registers have to be enabled
and programmed accurately before entering power-down.
Pay attention to add at least one
“NOP” instruction subsequent to the power-down instruction if I/O wake-up is used.
SFR:
PCON
(Power Control)
Bit-7
SMOD
Bit-6
reserved0
Bit-5
LVF
Bit-4
POF
Bit-3
GF1
Bit-2
GF0
Bit-1
PD
Bit-0
IDL
SMOD:=
Double baud rate of UART interface
0
: =
Keep normal baud rate when the UART is used in mode 1,2 or 3.
1
: =
Double baud rate when the UART is used in mode 1,2 or 3.
reserved0
:=
no use. Default set as 0. The user can not set it.
LVF:=
Low-Voltage Flag
After power-up, this bit will be initially set. The user should clear it by his program.
Continuously on operating, it will be set if the power supply drops under 3.7V/2.3V
(Operate in the 5V/3V).
POF:=
Power-On flag
This bit will be set after the device was powered on.
It must be cleared by the user’s software.
PD:=
Power-Down switch
Set this bit to drive the device enter
POWER-DOWN
mode.
IDL:=
Idle flag
Set this bit to drive the device enter
IDLE
mode.
58
MPC82x54A Data Sheet
MEGAWIN
MEGAWIN [ MEGAWIN TECHNOLOGY CO., LTD ]
