SIM802 Hardware Design
When DTR is in high level, and there is no on air and audio activity is required and no hardware
interrupt (such as GPIO interrupt or data on serial port), SIM802 will enter SLEEP mode
automatically. In this mode, SIM802 can still receive paging or SMS from network.
In SLEEP mode, the serial port is not accessible.
Note: For some special soft versions, it requests to set AT command “AT+CSCLK=1” to enable
the sleep mode; the default value is 0, that can’t make the module enter sleep mode. For more
details please refer to the AT command list.
3.6.3 SRD sleep mode (slow clocking mode)
The SRD sleep mode is reserved.
3.6.4 Wake up SIM802 from GSM sleep mode
When SIM802 GSM part is in sleep mode, the following methods can wake up the module.
z
Enable DTR Pin to wake up SIM802
If DTR Pin is pull down to a low level
，
this signal will wake up SIM802 from power saving
mode. The serial port will be active after DTR changed to low level for about 40mS.
z
Receiving a voice or data call from network to wake up SIM802
z
Receiving a SMS from network to wake up SIM802
z
RTC alarm expired to wake up SIM802
Note: DTR Pin should be held low level during communicating between the module and DTE.
3.7 Summary of state transitions (except sleep mode)
Table 11: Summary of state transitions
Power down
mode
Normal mode
Ghost mode
(Charge-only
mode)
Charging in normal
mode
Alarm mode
Power down
mode
Use
PWRKEY
Connect charger
to VCHG and
connect battery
to VBAT
No direct transition,
but via “Ghost
mode” or “Normal
mode”
Switch on
from
POWER
DOWN mode
by RTC
Normal
mode
AT+CPOWD
or use
PWRKEY
Pin
Connect charger
to VCHG and
connect battery
to VBAT, then
switch off
module by
Connect charger to
VCHG Pin of
module and connect
battery to VBAT Pin
of module
Set alarm by
“AT+CALAR
M”, and then
switch off the
module.
When the
Current
mode
Further
mode
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