User Manual

Table Of Contents
XT55/56 Hardware Interface Description
Confidential / Preliminary
s
XT55/56_hd_v02.96 Page 54 of 125 18.08.2005
3.6.5.1 Wake-up via /RTS0 and RTS1 (if AT+CFUN=0 or AT+CFUN=9)
During the CYCLIC SLEEP modes 5, 6, 7, and 8, GSM_RTS0 and GSM_RTS1 are
conventionally used for flow control: The assertion of GSM_RTS0 or GSM_RTS1 indicates
that the application is ready to receive data - without waking up the module.
If the module is in CFUN=0 mode the assertion of GSM_RTS0 and GSM_RTS1 serves as a
wake-up event, giving the application the possibility to intentionally terminate power saving. If
the module is in CFUN=9 mode, the assertion of GSM_RTS0 or GSM_RTS1 can be used to
temporarily wake up XT55/56 for the time specified with the AT^SCFG command (default =
2s). In both cases, if GSM_RTS0 or GSM_RTS1 is asserted while AT+CFUN=0 or
AT+CFUN=9 is set, there may be a short delay until the module is able to receive data again.
This delay depends on the current module activities (e.g. paging cycle) and may be up to
60ms. The ability to receive data is signalized by GSM_CTS0 and GSM_CTS1. It is therefore
recommended to enable RTS/CTS flow control, not only in CYCLIC SLEEP mode, but also in
NON-CYCLIC SLEEP mode.