Smart Machine Smart Decision
SIM800H _Hardware Design_V2.03
27
2016-10-10
4.3.5.
Wake Up SIM800H from Sleep Mode 2
When SIM800H is in sleep mode 2 (AT+CSCLK=2), the following methods can wake up the module:
Send data to SIM800H via main serial port (the first character will lose).
Receive a voice or data call from network.
Receive a SMS from network.
Note: Autobauding is default. It cannot enter sleep mode in the absence of synchronous serial port baud rate after module power
on.
4.4.
RTC Backup
Current input for RTC when the VBAT is not supplied for the system. Current output for backup battery when
the VBAT power supply is in present and the backup battery is in low voltage state. The RTC power supply of
module can be provided by an external capacitor or a battery (non-chargeable or rechargeable) through the VRTC.
The following figures show various reference circuits for RTC back up.
External capacitor backup
RTC
Core
2.2K
Module
VRTC
Large-capacitance
Capacitor
Figure 17: RTC supply from capacitor
Non-chargeable battery backup
RTC
Core
2.2K
Module
VRTC
Non-chargeable
Backup Battery
Figure 18: RTC supply from non-chargeable battery
Rechargeable battery backup
RTC
Core
2.2K
Module
VRTC
Rechargeable
Backup Battery
Figure 19: RTC supply from rechargeable battery
SIMCOM
CONFIDENTIAL
FILE
