TOBY-L4 series - System Integration Manual
UBX-16024839 - R04
System description
Page 42 of 143
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 17), 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 17: 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 18), if the feature is enabled by the AT+CNMI command (see the
u-blox AT Commands Manual
Figure 18: 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) then 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 SMSs.
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 suitable commands.
The
RI
line can additionally notify URCs and/or incoming data, if the feature is enabled by the specific 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 illustrated in Figure 18.
The
DTR
,
DSR
,
DCD
and
RI
pins can be alternatively configured for External Interrupt detection or as GPIO by
means of the uCPU API. The
RI
pin can be alternatively configured as GPIO by an AT command.
SMS arrives
time [s]
0
RI ON
RI OFF
1s
time [s]
0
RI ON
RI OFF
1s
1s
time [s]
15
10
5
0
RI ON
RI OFF
Call incomes
1s
time [s]
15
10
5
0
RI ON
RI OFF
Call incomes