Quectel M12 User Manual

M12 Hardware Design
M12_Hardware_Design_V3.3 - 35 -
 Receive a voice or data call from network to wake up module.
 Receive a SMS from network to wake up module.
Note: DTR pin should be held low level during communicating between the module and DTE.
c3.6. Summary of state transitions
Table 7: Summary of state transition
Current mode
Next mode
Power down
Normal mode
Sleep mode
Power down
Use PWRKEY
Normal mode
“AT+QPOWD”, use
PWRKEY pin, or use
EMERG_OFF pin
Use AT command
“AT+QSCLK=1” and
pull DTR up
Sleep mode
Use PWRKEY pin, or
use EMERG_OFF pin
Pull DTR down or
incoming call or SMS
or GPRS data
transmission
3.7. RTC backup
The RTC (Real Time Clock) can be supplied by an external capacitor or battery (rechargeable or
non-chargeable) through the pin VRTC. A 1.5K resistor has been integrated in the module for
current limiting. A coin-cell battery or a super-cap can be used to backup power supply for RTC.
The following figures show various sample circuits for RTC backup.
Module
RTC Core
1.5K
VRTC
Non-chargeable
Backup Battery
Figure 14: RTC supply from non-chargeable battery
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Quectel M12 Specifications

General

Brand	Quectel
Model	M12
Category	Control Unit
Language	English