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4. Signals and Indicators
4.1.
Alarm Mode
The USR3500 can be turned on using the Alarm mode when power supply is applied.
The USR3500 will remain in Low Power mode until the alarm is triggered to start the
USR3500 up.
Note:
Refer to section 3.1.1.2 ON/OFF Pin for more information on how to turn the USR3500 ON or OFF
using the ON/OFF pin.
Table 24.
Alarm Mode (Low Power Mode)
Steps
State
AT+CALA="YY/MM/DD,H
1
H:MM"
Pulled ON/OFF PIN to
2
GND
3
AT+CPOF
Note:
The USR3500' clock must be set before Alarm mode is activated. To set the clock, refer to the
AT+CCLK command in the AT Commands Interface Guide at http://www.usr.com/support/3500.
4.2.
RESET Signal Connection
This signal is used to force a reset procedure by providing the USR3500 with a LOW
level that lasts at least 200µs (when the power supply is already stabilized). It is
activated by either an external Reset signal or by an internal signal (from the Reset
generator); and is automatically driven by an internal hardware during the power ON
sequence.
Note:
The USR3500 remains in Reset mode for as long as the Reset signal is held LOW.
A software reset is always preferred to a hardware reset. Refer to document documents the AT
Commands Interface Guide at
software resets.
This signal may also be used to provide a reset to an external device when the pin is
configured as an output. If no external reset is necessary, this input may be left open.
When used (as an emergency reset), it has to be driven by either an open collector
or an open drain output.
Caution:
This signal is for emergency resets only.
Power Supply
4.75V to 32V supply is
applied.
4.75V to 32V supply is
applied.
4.75V to 32V supply is
applied. (The ON/OFF signal
remains at GND.)
http://www.usr.com/support/3500
Rev 1.0
Operation
The alarm is set.
The USR3500 remains ON.
The USR3500 remains ON.
The USR3500 turns OFF and will
remain OFF until the Alarm mode is
activated to turn the device ON.
for more information regarding
1/27/14
37
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