User's Manual

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Note d’étude / Technical document : URDx– OTL 5635.1– 007 / 70 230 Edition 03
Document Sagem Communications Reproduction et divulgation interdites
Sagem Communications document. Reproduction and disclosure prohibited
We need DTR active (low electrical level), a loop DSR on DTR is sufficient because DSR is active (low
electrical level) once the HiLo is switched on.
We also need RTS active (low electrical level), a loop RTS on CTS is sufficient because CTS is active (low
electrical level) once the HiLo is switched on.
DCD and RI can stay not connected and floating.
RXD
TXD
RTS
CTS
DCD
RI
DTR
DSR
RXD
TXD
RTS
CTS
DCD
RI
DTR
DSR
DCE
(HiLo)
DTE
(Host)
GND GND
Figure 14: Partial V24 connection (2 wires) between HiLo and host
3.7 SPI
HiLo module manages a host SPI interface. This SPI interface is dedicated for trace. Sagem communications
strongly recommends leaving this interface externally accessible for trace (e.g. access by test point pads).
3.8 GPIO
There are five GPIOs available on HiLo. The GPIO1, 2 and 3 have internal pull-up resistors while GPIO4 and 5
are open collector. So when using GPIO4 and 5 as output, they must be pulled up to VGPIO. The typical value
of the pull-up resisters is 100K ohms.
3.9 BACKUP BATTERY
3.9.1 Backup battery function feature
A backup battery can be connected to the module in order to supply internal RTC (Real Time Clock) when the main power
supply is removed. Thus, when the main power supply is removed, the RTC is still supplied and the module keep the time
running.
With external BACKUP:
- If VBAT < 3V, internal RTC is supplied by VBACKUP.
- If VBAT > =3V, internal RTC is supplied by VBAT.