Real Time Clock; Ulp Models - MTX -3G-JAVA series User Manual

4.10 Real Time Clock
The EHS6 module attached to MTX‐3G‐JAVA modems contains a real time clock (RTC) to maintain
accurate timekeeping and to enable you to "time stamp" messages.
This RTC is supplied by a separate voltage regulator which is also active when the MTX‐3G‐JAVA is in
power down mode and the power supply VIN is available. An alarm function is provided that allows
the MTX‐3G‐JAVA to wake up in Airplane mode without logging onto the GSM/UMTS network.
The MTX‐3G‐JAVA modems can also accommodate an independent battery or super‐cap inside to
maintain the date and time of the RTC when the power supply is disconnected. Both the battery and
the super‐cap will be charged when power supply is present again.
The size of the capacitor determines the duration of buffering when no voltage is applied to MTX‐3G‐
JAVA; the larger the capacitor, the longer the date and time will be saved. A serial 1kΩ resistor placed
on the board next to VDDLP limits the charged current of an empty capacitor or battery.
This capacitor is not fitted by default and must be ordered separately. Please contact
gsmsupport@matrix.es for more details.
4.10.1 ULP models
In addition to the module's internal RTC, ULP modems have its own external low‐power, battery
operated RTC. The RTC used is a DS1337 connected to the module's I2C bus at a 7‐bit address 0x68
hexadecimal.
Please refer to the DS1337 datasheet for details about using the RTC. You can configure it using I2C
related AT commands or via the I2C Java class. You can also contact gsmsupport@matrix.es
You can program alarms to wake‐up the modem at a specified date and time. Please refer to Section
4.10 for more information about Ultra Low Power features.
www.mtx‐terminals.com www.mtxm2m.com
MTX M2M® by MATRIX ELECTRONICA S.L.U
MTX‐3G‐JAVA Family
2015/10 v1.6
/
Page 68 109