User's Manual

DE910 Series Hardware User Guide
1vv0300951 Rev.9 – 2015-05-11
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Reserved. Page 25 of 77
TIP:
To check if the device has powered off, hardware line PWRMON must be monitored. When
PWRMON goes low, the device has powered off.
4.3. Hardware Reset
WARNING:
The Hardware Reset must not be used during normal operation of the device since it does not
detach the device from the network. It shall be kept as an emergency exit procedure to be
done in the rare case that the device gets stuck waiting for some network.
4.3.1. Hardware Unconditional Shutdown
To unconditionally shutdown the DE910, the pad HW_SHUTDOWN* must be tied low for at
least 200 milliseconds and then released.
A simple circuit to unconditionally shutdown the module is illustrated below:
NOTE:
Do not use any pull up resistor on the HW_SHUTDOWN* line or any totem pole digital
output. Using a pull up resistor may bring latch up problems on the DE910 power regulator
and result in improper functioning of the module. The line HW_SHUTDOWN* must be
connected only in open collector configuration.
TIP:
The unconditional hardware Shutdown must always be implemented on the boards and the
software must use it only as an emergency exit procedure.