Wavecom GR64 Application Note - page 21
1.
Network activity. In DRX Mode (see section 2.3), the Wireless CPU® awakens at
each expected network frame that may contain a notification of activity for the
Wireless CPU®. Such notifications include incoming calls, SMS messages or
interrogations. Network activity causes the Wireless CPU® to awaken for brief
periods, typically 30 to 40 milliseconds for each multiframe group interval.
The group interval can range from 2 x 234 milliseconds to 9 x 234
milliseconds as determined by the network provider. Network activity does
not restart the inactivity delay unless such activity results in an unsolicited
report to the Host.
2.
UART activity. If the Host issues an AT command, the Wireless CPU® is
awakened and the inactivity delay is begun. Any subsequent activity restarts
the inactivity delay.
3.
I/O pin activity. A change on any I/O pin enabled for trigger (see the E2IO
command in the AT Command User’s Manual) will cause the Wireless CPU® to
awaken. The unsolicited report from the I/O trigger will restart the inactivity
delay.
3.4
Waking the Wireless CPU® using an AT command
Unlike the GR47, the GR/GS64 Wireless CPU®s do not retain AT command sequences
entered while awakening. Therefore, your application must determine when the
Wireless CPU® is fully awake and ready to receive AT commands since the time until
the Wireless CPU® is fully awake is dependent on the DRX interval. We recommend
that you issue the character sequence “AT
termination character, typically carriage return until you receive an OK response from
the Wireless CPU®. Programmatically:
Do
Send “AT
Delay 200 milliseconds
If “OK” received then break from do loop, otherwise
Delay 200 milliseconds
End Do
If autobaud is enabled, you must use this sequence since “AT” triggers the UART to
recognize subsequent characters. If you use a fixed baud rate, you may wait for the
“A” to echo to indicate that the Wireless CPU® is awake, then complete the command.
The 200 millisecond delay shown above is only a suggestion and is not indicative of
any system requirement.
APPLICATION NOTE
GR/GS64 UART Sleep Protocols
Page: 21/26
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