Samsung S3C2440A - Manual (Page 223)

CLOCK & POWER MANAGEMENT S3C2440A RISC MICROPROCESSOR
7 -16
Follow the Procedure to Wake-up from SLEEP mode
1. The internal reset signal will be asserted if one of the wake-up sources is issued. It’s exactly same with the
case of the assertion of the external nRESET pin. This reset duration is determined by the internal 16-bit
counter logic and the reset assertion time is calculated as tRST = (65535 / XTAL_frequency).
2. Check GSTATUS2[2] in order to know whether or not the power-up is caused by the wake-up from SLEEP
mode.
3. Release the SDRAM signal protection by setting MISCCR[19:17]=000b.
4. Configure the SDRAM memory controller.
5. Wait until the SDRAM self-refresh is released. Mostly SDRAM needs the refresh cycle of all SDRAM row.
6. The information in GSTATUS[3:4] can be used for user’s own purpose because the value in GSTATUS[3:4]
has been preserved during SLEEP mode.
7. – For EINT[3:0], check the SRCPND register.
– For EINT[15:4], check the EINTPEND instead of SRCPND (SRCPND will not be set although some bits of
EINTPEND are set.).
Table 7-4. Pin configuration table in Sleep mode
Pin Condition Guid of Pin Configuration
which are configured as Input Pull-up Enable
GPIO Pin
which are configured as Ouput Pull-up Disable and Output Low
Input Pin, which doesn't have
internal Pull-up control. If External Device doesn't always
drive Pin's level.
Pull-up Enable by external Pull-up Resistor
If External Device's Power is Off Output Low
Output pin, which are
connected to External device
If External Device's Power is On
High or Low
(It depends on External device's status)
If Memory Power is Off Output Low
and External Buffer does exist If Buffer can hold bus level, Pull-up Disable.
Data
Bus
If Memory Power is On
and no External Buffer Output Low
NOTE
1. ADC should be set to Standby mode.
2. USB pads should be Suspend mode.
* This table is just for informational use only. User should consider his own Board condition and application.