Specifications

Wireless CPU
®
Q24 Series
Interfaces
©Confidential Page: 55 / 83
This document is the sole and exclusive property of WAVECOM. Not to be distributed or divulged without
prior written agreement.
WM_PRJ_Q24NG_PTS_001-004
January 16, 2007
The recommended way to de-assert the ON/~OFF signal is to use either an AT
command or WIND indicators: the application must detect the end of the power-up
initialization and de-assert ON/~OFF afterwards.
• Send an “AT” command and wait for the “OK” answer: once the initialization is
complete the AT interface answers « OK » to “AT” message
1
.
• Wait for the “+WIND: 3” message: after initialization, the Wireless CPU
®
, if
configured to do so, will return an unsolicited “+WIND: 3” message. The
generation of this message is enabled or disabled via an AT command.
Note:
See also “AT Commands Interface Guide”
[4] for more information on these
commands.
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-hold
) to ensure that the
firmware has already completed its power-up initialization.
The table below gives the minimum values of T
on-hold
for all firmware versions:
T
on-hold
minimum values
T
on-hold
Open AT
®
Firmware
Safe evaluations of the firmware
power-up time
6.57 & above 8 s
The above figures take the worst cases into account: power-loss recovery operations,
slow flash memory operations in high temperature conditions). But they are safe
because they are large enough to ensure that ON/~OFF is not de-asserted too early.
Remarks:
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
3.15.2.2 Power-OFF for an
alternate usage)
1
If the application manages hardware flow control, the AT command can be sent during the initialisation
phase.