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S5PC110_UM
6.2 SCENARIO DESCRIPTION
6.2.1 RESET STATUS
There are several scenarios for system reset such as hardware reset, watchdog reset, software reset, and wake
up from power down modes. For each scenario, the mandatory functions are summarized in
Initialization
Hardware Reset
Watchdog Reset
Wake up from
SLEEP
SW reset
Wake up from
DEEP_STOP
Wake up from
DEEP_IDLE
NOTE: When the contents of SRAM are preserved by retention option.
At the time of hardware reset and watchdog reset, the system should boot fully with the first boot loader and the
second boot loader and loading of OS image. The new reset status is classified as reset group0.
Since the contents of DRAM memory are preserved in the SLEEP mode, it does not require loading the OS image
to DRAM. However, SoC internal power is not supplied to internal logic during SLEEP mode and all contents in
internal SRAM are not preserved. Therefore, the first boot loader and the second boot loader should be loaded
again. This reset status is classified as reset group1.
At the time of software reset, The loading of boot loader is executed. Although top block's power is gated in
DEEP_STOP and DEEP_IDLE modes, the internal SRAM can be reserved, so that the re-loading of boot loader is
not required. In case of non-retention of SRAM in DEEP_STOP and DEEP_IDLE modes, the first boot loader
should be loaded again. These software reset that wake up from DEEP_STOP and DEEP_IDLE statuses are
classified as reset group2.
If system enters into all power down modes, the current system status should be saved to safe memory region
such as DRAM, so that the system continues processing seamlessly after waking up from power down modes.
Finally, the restoring previous state function is required on wake up from SLEEP, DEEP_STOP, and DEEP_IDLE
modes.
Table 6-1
Functions Needed for Various Reset Status
Basic
PLL Setting
in iROM
in iROM
O
O
O
O
O
O
O
O
O
X
O
X
First Boot /
DRAM Setting
Second Boot
in Second
Loader
Boot Loader
Loading
O
O
O
O
(note)
X
(note)
X
6 BOOTING SEQUENCE
Table 6-1
OS
Loading
O
O
O
O
O
X
O
O
X
X
X
X
Restore
Previous
State
X
X
O
X
O
O
6-3
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