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WM_PRJ_Q2686_PTS_001-010
June 30, 2009
Q2686 Wireless CPU
®
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
Open AT
®
Software
Suite v2
8 s (TBC)
The above figure take the worst cases into account: power-loss recovery
operations, slow flash memory operations in high temperature conditions, and
so on. But, they are safe because they are large 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 releasing 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 high 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 3.14.1.2
on Power-OFF for an alternate usage)
3
When using a battery as power source, it is not recommended to let
this signal high:
4
If the battery voltage is too low and the ON/~OFF signal at low level,
an internal mechanism switches OFF the Wireless CPU®. This
automatic process prevents the battery to be over discharged and
optimize its life span.
5
During the power-ON sequence, an internal reset is automatically
performed by the Wireless CPU® for 40 ms (typical). Any external reset
should be avoided during this phase.
6
After a reset (hardware or software), if the ON/~OFF signal is OFF
(Low level) the Wireless CPU® switches OFF.
