User's Manual

XT55/56 Hardware Interface Description
Confidential / Released
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XT55/56_hd_v02.06a Page 91 of 125 17.12.2004
Function Signal name IO Signal form and level Comments
Ignition GSM_IGT I
R
I
 100kΩ, C
I
 1nF
V
IL
max = 0.5V at Imax = -20µA
V
Open
max = 2.3V
ON
~~~
|____|
~~~
Active Low ≥ 100ms
Input to switch the mobile
ON.
The line must be driven low
by an Open Drain or Open
Collector driver.
Emergency
shutdown
(Watchdog)
GSM_EMERGOFF I/O
R
I
22kΩ
V
IL
max = 0.5V at Imax = -100µA
V
Open
max = 2.73V
Signal
~~~
|______|
~~~
Active Low ≥
3.2s
Watchdog:
V
OL
max = 0.35V at I = 10µA
V
OH
min= 2.25V at I = -10µA
f
O
min = 0.16Hz
f
O
max = 1.55Hz
This line must be driven by
an Open Drain or Open
Collector driver.
Emergency shutdown
deactivates the power supply
to the module.
The module can be reset if
GSM_IGT is activated after
emergency shutdown.
To switch the mobile off use
the AT^SMSO command.
To avoid floating if pin is high
impedance, use pull-down
resistor tied to GND. See
Chapter 3.3.2.1.
GSM_EMERGOFF also
indicates the internal
watchdog function.
If unused keep pin open.
V
OL
max = 0.2V at I = 1mA
V
OH
min = 2.35V at I = -1mA
V
OH
max = 2.73V
Indicates increased current
consumption during uplink
transmission burst. Note that
timing is different during
handover.
Alternatively used to control
status LED (see Chapter
3.12.2.2).
If unused keep pin open.
Synchroni-
zation
GSM_SYNC O
1 Tx, 877µs impulse each 4.616ms and
2 Tx, 1454µs impulse each 4.616ms,
with 300µs forward time.