Table 13-2. Clock And Enable States For Different Power Modes - Sharp LH79524 User Manual

Reset, Clock, and Power Controller
13.1.4 Power Modes
The RCPC supports five Power Modes:
• Active mode
• Standby mode
• Sleep mode
• Stop1 mode
• Stop2 mode.
Table 13-2 shows which clocks are enabled in the various Power Modes.
RTC Oscillator (32.768 kHz)
System Clock Oscillator
System and USB PLLs
System Clock
CPU Clock
13.1.4.1 Active Mode
Active Mode is the normal Power Mode. The SoC enters this mode after start-up and upon
exiting any other Power Mode. After an External Reset, Watchdog Timer Reset, or Soft
Reset is released, the System Reset is held active for an extra eight System Clock cycles
after the System Clock PLL is locked. The RTC oscillator is active, as it is in all modes.
13.1.4.2 Standby Mode
Standby Mode stops the clocks to the CPU and WDT while the rest of the device remains
active. Standby Mode is entered when software writes 0b001 to the PWRDWNSEL field of
the CTRL Register. When an interrupt is received, the RCPC exits Standby Mode and
ensures an orderly transition to Active Mode. An interrupt should be held active until the
RCPC exits Standby Mode. The RTC oscillator is active, as it is in all modes.
13.1.4.3 Sleep Mode
Sleep Mode stops all System Clocks, keeping only the PLLs, RTC Oscillator, and System
Clock Oscillator active. This mode is entered when software writes 0b010 to the PWRD-
WNSEL field of the CTRL Register. When an interrupt is received, the RCPC exits Sleep
Mode and ensures an orderly transition to Active Mode. An interrupt should be held active
until the RCPC exits Sleep Mode. The RTC oscillator is active, as it is in all modes.
13.1.4.4 Stop1 Mode
Stop1 Mode stops all System Clocks and disables the PLLs, but keeps the System Clock
Oscillator and RTC Oscillator active. This mode is entered when software writes 0b011 to
the PWRDWNSEL field of the CTRL Register. When an interrupt is received, the RCPC
exits Stop1 Mode and ensures an orderly transition to Active Mode. An interrupt should be
held active until the RCPC exits Stop1 Mode.
13-6

Table 13-2. Clock and Enable States for Different Power Modes

DEVICE
Version 1.0
LH79524/LH79525 User's Guide
ACTIVE STANDBY
ON ON
ON ON
ON ON
ON ON
ON OFF
SLEEP STOP1 STOP2
ON ON ON
ON ON OFF
ON OFF OFF
OFF OFF OFF
OFF OFF OFF