User's Manual
DE910 Series Hardware User Guide
1vv0300951 Rev.9 – 2015-05-11
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 22 of 77
During the Initialization state, any kind of AT-command is not available. DTE must wait for
the Activation state to communicate with DE910.
To check if the DE910 has powered on, the hardware line PWRMON must be monitored.
When PWRMON goes high, the module has powered on.
NOTE:
Do not use any pull up resistor on the ON_OFF* line. It is pulled up internally. Using a pull
up resistor may bring latch up problems on the DE910 power regulator and improper power
on/off of the module. The line ON_OFF* must be connected only in open collector
configuration.
NOTE:
In this document all the lines are inverted. Active low signals are labeled with a name that
ends with "*" or with a bar over the name.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the DE910 module when the module is powered OFF
or during an ON/OFF transition.
For example:
1. To drive the ON_OFF* pad with a totem pole output of a +3/5 V microcontroller
(uP_OUT1):
2. To drive the ON_OFF* pad directly with an ON/OFF button: