User's Manual

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Note d’étude / Technical document : URD1– OTL 5665.1– 002 / 70 884 Edition 03
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3.6.4 Partial V24 (RX-TX) – connection HiloNC - host
When using only RX/TX instead of the complete V24 link, we recommend following schematic.
Figure 16: Partial V24 connection (2 wires) between HiloNC and host
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We need DTR active (low electrical level), a loop DSR on DTR is sufficient because DSR is active (low
electrical level) once the HiloNC is switched on.
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We need RTS active (low electrical level), a loop RTS on CTS is sufficient because CTS is active (low
electrical level) once the HiloNC is switched on.
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DCD and RI can stay not connected and floating.
3.6.5 Design impact on DTR usage
The designer must consider when choosing V24 design that DTR can be used for several purposes :
- flow control of V24 interface (see chapter 3.6.2)
- enter/exit sleep mode of HiloNC module if AT+KSLEEP=0 has been configured (see chapter 3.14)
- switch between command/data modes
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Depending of the HiloNC/Host V24 connexion, the DTR can be usable by customer or not (if always
connected to DSR) and then has impact on sleep mode management and AT command/data modes
management.
3.7 SPI
HiloNC module manages a host SPI interface. This SPI interface is dedicated for trace.
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Sagem Communications strongly recommends leaving this interface externally accessible for trace (e.g.
access by test point pads).
DCE point of view DTE point of view
RXD
CTS
DSR
DCD
RI
DTR
TXD
RTS
HiLoNC 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