User's Manual
Table Of Contents
- Contents
- Table Index
- Figure Index
- 0. Revision history
- 1. Introduction
- 2. Product concept
- 3. Application interface
- 3.1. Pin
- 3.2. Operating modes
- 3.3. Power supply
- 3.4. Power on and down scenarios
- 3.5. Power saving
- 3.6. Summary of state transitions
- 3.7. RTC backup
- 3.8. Serial interfaces
- 3.9. Audio interfaces
- 3.10. SIM card interface
- 3.12. Behaviors of the RI
- 3.13. Network status indication
- 3.14. Operating status indication
- 4. Antenna interface
- 5. Electrical, reliability and radio characteristics
- 6. Mechanical dimensions
- 7. Storage and Manufacturing
- Appendix A: GPRS coding schemes
- Appendix B: GPRS multi-slot classes
M95 Hardware Design
M95_HD_V1.0 - 34 -
3.4.2.4. Emergency shutdown using EMERG_OFF pin
The module can be shut down by driving the pin EMERG_OFF to a low level voltage over 20ms
and then releasing it. The EMERG_OFF line can be driven by an Open Drain / Collector driver or a
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
S1
EMERG_OFF
TVS1
Close to S1
Figure 11: Reference circuit for EMERG_OFF by using button
3.4.2.5. Emergency shutdown using AT command
Using an AT command “AT+QPOWD=0” can achieve emergency shutdown of the module. In
this situation, No URC returns back to the host no matter in the fixed band rate or auto band rate.
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 shut
down the system. Although turning off the module by EMERG_OFF is fully tested and nothing
wrong 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.