C8051F360/1/2/3/4/5/6/7/8/9
SFR Definition 9.9. ACC: Accumulator
SFR Page:
all pages
SFR Address: 0xE0
(bit addressable)
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
R/W
R/W
ACC.7
Bit7
ACC.6
Bit6
ACC.5
Bit5
ACC.4
Bit4
ACC.3
Bit3
ACC.2
Bit2
ACC.1
Bit1
ACC.0
Bit0
00000000
Bits 7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
SFR Definition 9.10. B: B Register
SFR Page:
all pages
SFR Address: 0xF0
(bit addressable)
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
R/W
R/W
B.7
Bit7
B.6
Bit6
B.5
Bit5
B.4
Bit4
B.3
Bit3
B.2
Bit2
B.1
Bit1
B.0
Bit0
00000000
Bits 7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
9.5.
Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the external peripherals and internal clocks active. In Stop mode, the CPU is
halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the system clock is
stopped. Since clocks are running in Idle mode, power consumption is dependent upon the system clock
frequency and the number of peripherals left in active mode before entering Idle. Stop mode consumes the
least power. SFR Definition 9.11 describes the Power Control Register (PCON) used to control the CIP-
51's power management modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and put into low power mode. Digital
peripherals, such as timers or serial buses, draw little power whenever they are not in use. Turning off the
Flash memory saves power, similar to entering Idle mode. Turning off the oscillator saves even more
power, but requires a reset to restart the MCU.
The C8051F36x devices feature an additional low-power SUSPEND mode, which stops the internal oscil-
lator until an awakening event occurs. See Section “16.1.1. Internal Oscillator Suspend Mode” on
104
Rev. 1.0
SILABS [ SILICON LABORATORIES ]
