User's Manual

HiLo3G-850 User Manual
04 March 2011 - Page 21 / 36
Thanks to some other special AT commands, GPIOs can for example be used:
1. Make an I/O toggling while the module is attached to the network
2. Make an I/O toggling when a programmed temperature is reached
3. As input to detect the presence of an antenna (with some external additional electronic)
4. As input to detect the SIM card presence …etc
3.7 ADC
There is one ADC input pin which can be used to read the value of the voltage applied. Following characteristics must be
fullfilled to allow proper performances:
• The input signal voltage must be within 0V and up to 2.1V
• The input impedance of the pin is 2KΩ
• The input capacitance is typically 53pF.
The AT command AT+KADC will return the voltage value with the following characteristics:
• 12 bits resolution
• Maximum sampling frequency is 2.4MHz.
3.8 Backup Battery
3.8.1 Backup Battery Function Feature
3.8.1.1 With Backup Battery
A backup battery can be connected to the module in order to supply internal RTC (Real Time Clock) when the main power
supply is removed. Thus, when the main power supply is removed, the RTC is still supplied with power and the module
keeps the time register running.
• If VBAT < 3V, internal RTC is supplied by VBACKUP.
• If VBAT ≧3V, internal RTC is supplied by VBAT.
3.8.1.2 Without Backup Battery
Without backup battery
If VBAT ≥ 1.5V, internal RTC is supplied by VBAT.
If VBAT < 1.5V, internal RTC is not supplied.
To calculate the backup battery capacity; consider that current consumption for RTC on the backup battery is up to 2µA
depending on the temperature.
Pin Name
Min
Max
VBACKUP
2uA
3.8.2 Charge by Internal HiLo3G-850 Charging Function
The charging function is available on HiLo3G-850 without any additional external power supply (the charging power
supply is provided by the HiLo3G-850).
Charge of the back-up battery occurs only when main power supply VBAT is provided.
Figure 23: Backup battery or 10μF capacitor internally charged