SimCom SIM548C HD V1.01, Проектирование аппаратного обеспечения

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SIM548C Hardware Design
z 4: disable phone both transmit and receive RF circuits;
If the GSM part of the module has been set to minimum functionality by “AT+CFUN=0”, then the
RF function and SIM card function will be closed. In this case, the serial port is still accessible,
but all AT commands need RF function or SIM card function will not be accessible.
If the GSM part of the module has been set by “AT+CFUN=4”, the RF function will be closed,
the serial port is still active. In this case but all AT commands need RF function will not
accessible.
After the GSM part of the module has been set by “AT+CFUN=0” or “AT+CFUN=4”, it can
return to full functionality by “AT+CFUN=1”
For detailed information about “AT+CFUN”, please refer to
document [1]
.
3.6.2 SLEEP mode (slow clock mode)
We can control the GSM part of the module to enter or exit the SLEEP mode in customer
applications through DTR signal.
When DTR is in high level and there is no on air and hardware interrupt (such as GPIO interrupt
or data on serial port), the GSM part of the module will enter SLEEP mode automatically. In this
mode, the GSM part of the module can still receive paging or SMS from network.
In SLEEP mode, the serial port is not accessible.
Note: For some special software 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 our AT command list.
3.6.3 Wake up the GSM part from SLEEP mode
When the GSM part of the module is SLEEP mode, the following method can wake up the module
z Enable DTR pin to wake up the GSM part of the module
If DTR pin is pull down to a low level
，
this signal will wake up the GSM part of the module
from power saving mode. The serial port will be active after DTR changed to low level for
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