User's Manual

TOBY-R2 series - System Integration Manual
UBX-16010572 - R04 System description
Page 42 of 147
RI signal behavior
The RI module output line is set by default to the OFF state (high level) at UART initialization.
The RI line can notify an incoming call: the RI line is switched from the OFF state to the ON state with a 4:1 duty
cycle and a 5 s period (ON for 1 s, OFF for 4 s, see Figure 19), until the DTE attached to the module sends the
ATA string and the module accepts the incoming data call. The RING string sent by the module (DCE) to the
serial port at constant time intervals is not correlated with the switch of the RI line to the ON state.
Figure 19: RI behavior during an incoming call
The RI output line can notify an SMS arrival. When the SMS arrives, the RI line switches from OFF to ON for 1 s
(see Figure 20), if the feature is enabled by AT+CNMI command (see the u-blox AT Commands Manual [2]).
Figure 20: RI behavior at SMS arrival
This behavior allows the DTE to stay in power saving mode until the DCE related event requests service.
For SMS arrival, if several events coincidently occur or in quick succession each event independently triggers the
RI line, although the line will not be deactivated between each event. As a result, the RI line may stay to ON for
more than 1 s, if an incoming call is answered within less than 1 s (with ATA or if auto-answering is set to
ATS0=1) than the RI line is set to OFF earlier, so that:
RI line monitoring cannot be used by the DTE to determine the number of received SMSes.
For multiple events (incoming call plus SMS received), the RI line cannot be used to discriminate the two
events, but the DTE must rely on subsequent URCs and interrogate the DCE with the proper commands.
The RI line can additionally notify all the URCs and/or all the incoming data in PPP and Direct Link connections, if
the feature is enabled by the AT+URING command (for more details see the u-blox AT Commands Manual [2]):
the RI line is asserted when one of the configured events occur and it remains asserted for 1 s unless another
configured event will happen, with the same behavior described in Figure 20.
SMS arrives
time [s]
0
RI ON
RI OFF
1s
time [s]
0
RI ON
RI OFF
1s
1s
time [s]
151050
RI ON
RI OFF
Call incomes
1s
time [s]
151050
RI ON
RI OFF
Call incomes