M12 Hardware Design
M12_Hardware_Design_V3.3
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button. The circuit is illustrated as the following figures.
Emergency
shutdown pulse
EMERG_OFF
4.7K
47K
Figure 10: Reference circuit for EMERG_OFF by using driving circuit
EMERG_OFF
S1
Close to S1
TVS
Figure 11: Reference circuit for EMERG_OFF by using button
Be cautious to use the pin EMERG_OFF. It should only be used under emergent situation. For
instance, if the module is unresponsive or abnormal, the pin EMERG_OFF could be used to
shutdown the system. Although turning off the module by EMERG_OFF is fully tested and nothing
wrong is detected, this operation is still a big risk as it could cause destroying of the code or data
area of the NOR flash memory in the module. Therefore, it is recommended that PWRKEY or AT
command should always be the preferential way to turn off the system.
3.4.3. Restart module using PWRKEY pin
Customer’s application can restart the module by driving the PWRKEY to a low level voltage for
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