User's Manual

page 24/64
Note d’étude / Technical document : URD1– OTL
5665.3 – 003 / 72238 Edition 01
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DCD and RI can stay not connected and floating when not used.
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RI signal is a stand alone signal that can be used with anyone of the following configuration. Consult the
AT command specification for more information about this signal and its use.
This configuration allows to use the flow control RTS & CTS to avoid any overflow error during the data transfer,
CTS is moreover used to signal when the HiLoNC V2 is ready to receive an AT command after a power up
sequence or a wake up from sleep mode.
Figure 23: CTS versus POK_IN signal during the power on sequence.
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However this configuration does not allow the signalling signals like:
• RI signal used when programmed to indicate an incoming voice or data call or SMS incoming etc…
• DCD signal used to signal the GPRS connections
• DSR signal used to signal the module UART interface is ON
• DTR signal used to prevent the HiLoNC V2 module from entering into sleep mode or to switch between
Data and AT commands or to hang up a call or to wake up the module etc…
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Consult the AT command Specification document for the uses of the UART signals.
4.7.5 Partial V24 (RX-TX) – connection HiLoNC V2 - host
When using only RX/TX instead of the complete V24 link, the following schematic could be used.
Figure 24: Partial V24 connection (2 wires) between HiloNC V2 and host
DCE point of view DTE point of view
RXD
CTS
DSR
DCD
RI
DTR
TXD
RTS
HiLoNC V2 Module
TXD
CTS
DSR
DCD
RI
DTR
RXD
RTS
DTE Device
2.8V signals
39
40
33
34
35
36
38
37
2.8V signals
Note: GND is not
represented