SIM Tech SIM900D HD, Manual

Page: 21 / 61

SIM900D Hardware Design
PWM O PWM Output VOHmin= 2.7V
VOLmax=0.1V
VOHmax= 3V
VOLmin= 0V If unused keep
open
3.2 Operating Modes
The table below briefly summarizes the various operating modes referred to in the following chapters.
Table6: Overview of operating modes
Mode Function
GSM/GPRS
SLEEP Module will automatically go into SLEEP mode if DTR is set to high level
and there is no on air and no hardware interrupt (such as GPIO interrupt or
data on serial port).
In this case, the current consumption of module will reduce to the minimal
level.
In SLEEP mode, the module can still receive paging message and SMS
from the system normally.
GSM IDLE Software is active. Module has registered to the GSM network, and the
module is ready to send and receive.
GSM TALK
Connection between two subscribers is in progress. In this case, the power
consumption depends on network settings such as DTX off/on,
FR/EFR/HR, hopping sequences, antenna.
GPRS
STANDBY Module is ready for GPRS data transfer, but no data is currently sent or
received. In this case, power consumption depends on network settings and
GPRS configuration.
Normal
operation
GPRS DATA There is GPRS data transfer (PPP or TCP or UDP) in progress. In this case,
power consumption is related with network settings (e.g. power control
level), uplink / downlink data rates and GPRS configuration (e.g. used
multi-slot settings).
POWER
DOWN Normal shutdown by sending the “AT+CPOWD=1” command or using the PWRKEY. The
power management ASIC disconnects the power supply from the baseband part of the
module, and only the power supply for the RTC is remained. Software is not active. The
serial port is not accessible. Operating voltage (connected to VBAT) remains applied.
Minimum
functionality
mode (without
remove power
supply) Use the “AT+CFUN” command can set the module to a minimum functionality mode
without remove the power supply. In this case, the RF part of the module will not work or the
SIM card will not be accessible, or both RF part and SIM card will be closed, and the serial
port is still accessible. The power consumption in this case is very low.
Charge-only Charge-only
mode
means: charging when power down. In this mode, the module can not be
SIM900D_HD_V1.02 09.04.2010
21