Sim800 hardware design v1.05
Table Of Contents
- Version History
- 1. Introduction
- 2. SIM800 Overview
- 3. Package Information
- 4. Application Interface
- 4.1. Power Supply
- 4.2. Power on/down SIM800
- 4.3. Power Saving Mode
- 4.4. RTC Backup
- 4.5. Serial Port and USB Interface
- 4.6. RI Behaviors
- 4.7. Audio Interfaces
- 4.8. Bluetooth
- 4.9. SIM Card Interface
- 4.10. PCM Interface
- 4.11. Keypad Interface
- 4.12. I2C BUS
- 4.13. General Purpose Input/Output (GPIO)
- 4.14. ADC
- 4.15. PWM
- 4.16. Network Status Indication
- 4.17. Operating Status Indication
- 4.18. KPLED
- 4.19. RF Synchronization Signal
- 4.20. Antenna Interface
- 5. PCB Layout
- 6. Electrical, Reliability and Radio Characteristics
- 6.1 Absolute Maximum Ratings
- 6.2 Recommended Operating Conditions
- 6.3 Digital Interface Characteristics
- 6.4 SIM Card Interface Characteristics
- 6.5 SIM_VDD Characteristics
- 6.6 VDD_EXT Characteristics
- 6.7 VRTC Characteristics
- 6.8 Current Consumption (VBAT=4V)
- 6.9 Electro-Static Discharge
- 6.10 Radio Characteristics
- 6.11 Module RF Receive Sensitivity
- 6.12 Module Operating Frequencies
- 7. Manufacturing
- 8. Appendix
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SIM800_Hardware Design_V1.05 25 2014-03-25
4.2.2.3. Over-voltage or Under-voltage Power down
The module software monitors the VBAT voltage constantly.
If the voltage 3.5V, the following URC will be reported:
UNDER-VOLTAGE WARNNING
If the voltage 4.3V, the following URC will be reported:
OVER-VOLTAGE WARNNING
If the voltage < 3.4V, the following URC will be reported, and the module will be automatically powered down.
UNDER-VOLTAGE POWER DOWN
If the voltage > 4.4V, the following URC will be reported, and the module will be automatically powered down.
OVER-VOLTAGE POWER DOWN
At this moment, AT commands can not be executed any more, and only the RTC is still active. Power down mode
can also be indicated by STATUS pin, which is low level at this time.
4.2.2.4. Over-temperature or Under-temperature Power down
The module will constantly monitor the temperature of the module,
If the temperature > +80°C, the following URC will be reported:
+CMTE: 1
If the temperature < -30°C, the following URC will be reported:
+CMTE:-1
If the temperature > +85°C, the following URC will be reported, and the module will be automatically powered
down.
+CMTE: 2
If the temperature < -40°C, the following URC will be reported, and the module will be automatically powered
down.
+CMTE:-2
At this moment, AT commands can not be executed any more, and only the RTC is still active. Power down
mode can also be indicated by STATUS pin, which is at low level at this time.
Note: Temperature detection is disable by default, the AT command “AT+CMTE” could be used to read the
temperature when the module is running. For details please refer to document [1].
4.2.3. Reset Function
SIM800 also have a RESET pin used to reset the module. This function is used as an emergency reset only when
AT command “AT+CPOWD=1” and the PWRKEY pin have no effect. User can pull the RESET pin to ground,
and then the module will restart.
This pin is already isolated in the module, so the external isolation is not necessary. Following figure is internal
circuit of the RESET pin.