2.4.6
DSR1 Timing
Two time periods are significant in the functioning of DSR:
Figure 7.
DSR functioning time periods
period
a
: this is fixed in the GR/GS64 application to 500ms, the time-out period for
the Host to respond to a sleep request from the Wireless CPU®.
period
b
: this is programmable by the user, known as the
inactivity period. It defines
the interval since the Wireless CPU®’s last de-assertion of DSR1 until it is able to
perform another de-assertion (sleep request). Furthermore, it is intended for
inactivity on the UART in general. Under ‘normal conditions’, the interval timeout
timer will begin after sending or receiving characters on DTM/DFM. This interval is
also valid for cases where the Wireless CPU® has awoken from a legitimate period of
sleep. This period is programmed by the user with the AT command AT*E2RS232,
selecting the appropriate <itimr> inactivity timer value (refer to the GR64 & GS64 AT
Command Manual for details). The inactivity timer is programmable from 100 to
2000 milliseconds.
2.4.7
Sleep Mode Enabling and Disabling
Sleep mode capability can be enabled and disabled by using the AT command
AT*E2RS232, selecting the appropriate <val> and <sel> parameters (refer to the
GR64 & GS64 AT Command Manual for details).
In the event that the Host fails to respond to three consecutive
attempts by the Wireless CPU® to request sleep mode (as illustrated
in Para. 2.4.6), Standby Handshaking (sleep) mode will be
automatically disabled. The user will have to re-enable the feature
(using AT*E2RS232) before sleep mode can be re-enacted.
CAUTION
The Wireless CPU® will attempt to sleep whenever possible, once the sleep
handshaking is enabled. When the Wireless CPU® is first powered it will generally
attempt network registration, then typically the Host and Wireless CPU® will perform
some configuration procedures and a further exchange of communication. This may
take between ten and thirty seconds, longer if there is network congestion. It may be
prudent to wait until after this preliminary activity before enabling sleep handshaking.
Enabling sleep handshaking beforehand may interfere with registration and set-up.
APPLICATION NOTE
GR/GS64 UART Sleep Protocols
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