User’s Manual
9-1
05.99
Power Saving Modes
C513AO
9
Power Saving Modes
The C513AO microcontroller provides three basic power-saving modes: Idle Mode, Slow-down
Mode, and Power-down Mode.
The functions of the power-saving modes are controlled by bits located in the Special Function
Register PCON. PCON is located at SFR address 87H. PCON1 is located in the mapped SFR area
at address 88
H
and is accessed with RMAP = 1. Bit RMAP is located in SFR SYSCON (B1H) bit 4.
Bits PDE and IDLE, located in SFR PCON, select the Power-down Mode or the Idle Mode
respectively. If the Power-down Mode and the Idle Mode are set at the same time, Power-down
takes precedence. Slow-down Mode is controlled by bit SD, located in SFR PCON.
Furthermore, register PCON contains two general purpose flags. For example, the flag bits GF0
and GF1 can be used to indicate that an interrupt occurred during normal operation or during an
Idle Mode. Then, an instruction which activates Idle Mode can also set one or both flag bits. When
Idle Mode is terminated by an interrupt, the interrupt service routine can examine the flag bits.
Special Function Register PCON (Address 87H)
Reset Value: 0XX00000B
Symbol
Function
–
Not implemented. Reserved for future use.
SD
Slow-down Mode Bit
When set, the Slow-down Mode is enabled (default is Slow-down disabled).
GF1
General purpose flag
GF0
General purpose flag
PDE
Power-down Enable Bit
When set, power-down mode is entered.
IDLE
Idle Mode Enable Bit
When set, idle mode is entered.
MSB
LSB
87H
PCON
SMOD
–
–
SD
GF1
GF0
PDE
IDLE
7
6
5
4
3
2
1
0
Bit No.
The function of the shaded bit is not described in this section.