User's Manual

CE910 Family Hardware User Guide
1vv0301010 Rev.11 – 2015-10-27
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 21 of 75
During the Initialization state, any kind of AT-command is not available. DTE must wait for the
Activation state to communicate with CE910.
To check if the CE910 has powered on, the hardware line VAUX/PWRMON must be monitored.
When VAUX/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 with 200kΩ internally. Using a
pull up resistor may bring latch up problems on the CE910 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 CE910 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: