EGS5 Hardware Interface Description
3.3 Power Up / Power Down Scenarios
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EGS5_HD_v02.004
Page 29 of 123
2012-02-09
Confidential / Released
3.3.1.1
Turn on EGS5 Using Ignition Line IGT
When the EGS5 module is in Power-down mode or Charge-only mode, it can be started to Nor-
mal mode or Airplane mode by driving the IGT (ignition) line to ground. This must be accom-
plished with an open drain/collector driver to avoid current flowing into this line.
The module will start up when both of the following two conditions are met:
•
The supply voltage applied at BATT+ must be in the operating range.
•
The IGT line needs to be driven low for at least 400ms in Power-down mode or at least 2s
in Charge-only mode.
Considering different strategies of host application design the figures below show two approach-
es to meet this requirement: The example in
assumes that IGT is activated after BATT+
has already been applied. The example in
assumes that IGT is held low before BATT+
is switched on. In either case, to power on the module, ensure that low state of IGT takes at least
400ms (Power-down mode) or 2s (Charge-only mode) from the moment the voltage at BATT+ is
available. For Charge-only mode see also
Assertion of CTS indicates that the module is ready to receive data from the host application.
In addition, if configured to a fixed bit rate (AT+IPR
0), the module will send the URC “^SYS-
START” or “^SYSSTART AIRPLANE MODE” which notifies the host application that the first
AT command can be sent to the module. The duration until this URC is output varies with the
SIM card and may take a couple of seconds.
Please note that no “^SYSSTART” or “^SYSSTART AIRPLANE MODE” URC will be generated
if autobauding (AT+IPR=0) is enabled.
To allow the application to detect the ready state of the module we recommend using hardware
flow control which can be set with AT\Q or AT+IFC (see
for details). The default setting of
EGS5 is AT\Q0 (no flow control) which shall be altered to AT\Q3 (RTS/CTS handshake). If the
application design does not integrate RTS/CTS lines the host application shall wait at least for
the “^SYSSTART” or “^SYSSTART AIRPLANE MODE” URC. However, if the URCs are neither
used (due to autobauding) then the only way of checking the module’s ready state is polling.
To do so, try to send characters (e.g. “at”) until the module is responding.
See also
"Signal States after Startup”.
