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TOBY-R2 series - System integration manual
UBX-16010572 - R10
System description
Page 40 of 151
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The DCD line is kept in the ON state, even during the online command mode
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, to indicate that the
data call is still established even if suspended, while if the module enters command mode
, the
DSR line is set to the OFF state. For more details see DSR signal behavior description.
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For scenarios when the DCD line setting is requested for different reasons (e.g. SMS texting
during online command mode
), the DCD line changes to guarantee the correct behavior for all the
scenarios. For example, in case of SMS texting in online command mode
, if the data call is
released, DCD is kept ON till the SMS command execution is completed (even if the data call
release would request DCD set OFF).
If AT&C0 is set, the DCD module output line is set by default to the ON state (low level) at UART
initialization and is then always held in the ON state.
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
), 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
), if the feature is enabled by AT+CNMI command (see the u-blox AT
commands manual
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.
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For the definition of the data mode, command mode and online command mode see the u-blox AT commands manual
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
RI OFF
RI ON
Call incomes
Time[s]
SMS arrives
time [s]
0
RI ON
RI OFF
1s
time [s]
0
RI ON
RI OFF
1s