Specifications

Product Technical Specification & Customer Design Guidelines
Interfaces
Proceeding thus by software detection will always prevent the application from de-
asserting the ON/OFF signal too early.
If WIND indicators are disabled or AT commands unavailable or not used, it is still
possible to de-assert ON/OFF after a delay long enough (T
on/off-hold
) to ensure that the
firmware has already completed its power-up initialization.
The table below gives the minimum values of T
on/off-hold
:
T
on/off-hold
minimum values
T
on/off-hold
Open AT
®
Firmware
Safe evaluations of the firmware
power-up time
6.65 & above 8 s
The above figure refers to the worst cases: power-loss recovery operations, slow
flash memory operations in high temperature conditions, and so on. But they are safe
because they are long enough to ensure that ON/OFF is not de-asserted too early.
Additional notes:
1.
Typical power-up initialization time figures for best cases conditions (no
power-loss recovery, fast and new flash memory…) approximate 3.5 seconds
in every firmware version. But setting ON/OFF after this delay does not
guarantee that the application will actually start-up if for example the power
plug has been pulled off during a flash memory operation, like a phone book
entry update or an AT&W command…
2.
The ON/OFF signal can be left at a low level until switch OFF. But this is not
recommended as it will prevent the AT+CPOF command from performing a
clean power-off. (see also Note in section
3.14.3.2 Power-OFF for an
alternate usage)
3. When using a battery as power source, it is not recommended to let this
signal low:
If the battery voltage is too low and the ON/OFF signal is at high level, an
internal mechanism switches OFF the Wireless CPU
®
. This automatic process
prevents the battery from being discharged and optimize its life span.
4.
During the power-ON sequence, an internal reset is automatically performed
by the Wireless CPU
®
for 40 ms (typically). Any external reset should be
avoided during this phase.
5.
Connecting a charger on the Wireless CPU
®
has exactly the same effect than
setting the ON/OFF signal; the Wireless CPU
®
will not Power-OFF after the
AT+CPOF command, unless the charger is disconnected.
3.14.3.2 Power-OFF
In Q64 Wireless CPU
®
without GR plug-in embedded, to power-OFF the Wireless
CPU
®
correctly, the application must set the ON/OFF signal to high level and then
send the AT+CPOF command to de-register from the network and switch OFF the
Wireless CPU
®
.
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prior written agreement.
WA_DEV_Q64_PTS_001-003 January 9, 2009