User's Manual

720 Hardware User Guide

When the module is running, the LED indicator is driven by the NET_LIGHT pin to indicate

different module status with its various blink behaviors. N720 supports multiple blink style and

you can configure it using AT commands.

2.6.4 DTR

Generally, DTR is used to control sleep mode together with AT commands. Enable the sleep

mode function by AT command. Then pulling DTR low will bring the module into sleep mode if the

module is idle. In this mode, the idle current is less than 4 mA, depending on the DRX setting of

network.

In sleep mode, the module can respond to the incoming call, SMS, and GPRS data. The host

MCU can also control the module to exit sleep mode by controlling DTR.

Process of entering sleep mode:

1. Keep DTR high level in normal working mode. Activate the sleep mode by using the

AT+ENPWRSAVE=1 command.

2. Pull DTR low, and the module will enter sleep mode, but only after process and pending data

finished.

3. In sleep mode, the external MCP can pull DTR high so that the module will exit from sleep

mode actively. Then the module can transmit data and initiate calls. After processing is

finished, pull DTR low again to take the module back to sleep mode.

4. In sleep mode, the module can be woken up by the events of incoming voice call, received

data, or SMS. Meanwhile the module will send out the unsolicited messages through the

UART.

Upon receipt of the unsolicited messages, the host MCU should pull DTR high firstly,

otherwise the module will resume sleep mode in two minutes after the service processing.

Then the host MCU can process the voice call, received data, or SMS. After processing is

finished, pull DTR low again to put the module into sleep mode.

2.6.5 RING Signal Indicator

 Calling: Once a voice call is incoming, UART outputs "RING" character strings and

meanwhile the RING pin outputs 30 ms low pulses at 5s period. After the call is answered,

the high level restores.