5.19 Burst Transmission (TX_ON)

Pin

 

Name

 

Direction

 

Function

 

 

 

 

 

 

 

39

 

TX_ON

 

Output

 

Transmit indication

Burst transmission is the period during which the GSM transceiver is transmitting RF signals. TX_ON is an indicator that the module is transmitting.

A typical application may use TX_ON to blank adjacent receiver circuitry as a means of protecting sensitive input stages.

5.20 Real Time Clock

The real-time clock (RTC) is driven by a 32.768 kHz clock from an internal crystal oscillator. The clock is divided by 32,768 to generate a clock with a 1 second period that increments a 29-bit seconds counter. In addition, it can generate interrupts at a programmed time. The following are the features of RTC:

•17-year time interval with 1 second resolution.

•Programmed time alarm interrupt

•Alarm output pin

An RTC alarm can be set by using the AT-command AT+CALA.

The RTC relies on an uninterrupted 1.5 V (nominal) power supply (VRTC), whether the module is powered off or on. The RTC alarm operates from the VRTC supply, and therefore utilize 1.5 V logic. Users have the responsibility to provide a backup battery to provide uninterrupted VRTC function when the module is powered down.

RTC Accuracy

Parameter

 

Condition

 

Max

 

Unit

 

 

 

 

 

 

 

RTC accuracy

 

Ambient (+25±2°C) operation

 

52.6

 

Secs/month

RTC accuracy

 

Extreme temperatures

65.2

 

Secs/month

LZT 123 1836

69