User's Manual

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Note d’étude / Technical document : URD1 – 5625.1 – 006 / 69796 Edition 03
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3.4 Power supply
The MO300 module can be supplied by battery or any DC/DC converter compliant with the module supply
range 3.3Vmin and up to 5.5Vmax 2A.
The PCB tracks must be well dimensioned to support 2A maximum current.
Maximum serial resistance on VBAT = 170mΩ internal resistance of the battery plus tracks and contact
resistance of the connectors for a new battery, or tracks & contact resistance of the connectors for a DC/DC
converter.
Case of old batteries: If this value is overran, this can cause erratic reset of the module when the
battery begins to be discharged.
The VBAT_CNT signal disturbs the other signal; it has to be isolated with ground from the other signals,
especially radio and audio signals.
In case of batteries, it is mandatory to use Li-Ion or Li-Polymer batteries.
NOTE: The MO300 M2M module does not
manage the charge of any kind of batteries.
3.5 V24 UART
The MO300 module feature a V24 UART interface plus a USB2 OTG interface to communicate with the Host
through AT commands or for easy firmware upgrading purpose.
3.5.1 Complete V24 – connection MO300 - host
A V24 UART interface is provided on the main connector of the MO300 module with the following signals:
RTS/CTS, RXD/TXD, DSR, DTR, DCD, RI.
It is recommended to manage an external access to the V24 interface, in order to allow easy software upgrade,
especially when USB is not planed to be used.
Figure 20
Complete V24 UART connection between MO300 and host
3.5.2 Complete V24 interface with PC
It supports speeds up to 115.2 KBPS and may be used in auto bauding mode as well.
To use the V24 interface, some adaptation components are necessary to convert the +1.8V signals from
the MO300 to +5V signals compatible with a PC.
RXD
TXD
RTS
CTS
MO300
DCD
DTR
DSR
RI
GND
RXD
TXD
RTS
CTS
Host
DCD
DTR
DSR
RI
GND