User Manual

MC45 Hardware Interface Description
P R E L I M I N A R Y
MC45_HD_01_V00.02a Page 35 of 90 12.08.2002
3.3.1.3 Turn on MC45 using the POWER signal
As detailed in Chapter 3.2.3.4, the charging adapter can be connected regardless of the
module’s operating mode (except for Alarm mode).
If the charger is connected to the POWER pins of the external charging circuit and of the
module while MC45 is off, processor controlled fast charging starts (see Chapter 3.2.3.3).
MC45 enters a restricted mode, referred to as Charge-only mode where only the charging
algorithm will be launched.
During the Charge-only mode MC45 is neither logged on to the GSM network nor is the RS-
232 interface fully accessible. To switch to normal operation and log on to the GSM network,
the /IGT line needs to be activated.
3.3.1.4 Turn on MC45 using the RTC (Alarm mode)
Another power-on approach is to use the RTC, which is constantly supplied with power from
a separate voltage regulator in the power supply ASIC. The RTC provides an alert function
which allows to wake up MC45 while power is off. To prevent the engine from unintentionally
logging into the GSM network, this procedure only enables restricted operation, referred to
as Alarm mode. It must not be confused with a wake-up or alarm call that can be activated
by using the same AT command, but without switching off power.
Use the AT+CALA command to set the alarm time. The RTC retains the alarm time if MC45
was powered down by AT^SMSO. Once the alarm is timed out and executed, MC45 enters
into the Alarm mode. This is indicated by an Unsolicited Result Code (URC) which reads:
^SYSSTART ALARM MODE
In Alarm mode only a limited number of AT commands is available. For further instructions
refer to the AT Command Set.
Table 9: AT commands available in Alarm mode
AT command Use
AT+CALA Set alarm time
AT+CCLK Set date and time of RTC
AT^SBC In Alarm mode, you can only query the present current consumption and check
whether or not a charger is connected. The battery capacity is returned as 0,
regardless of the actual voltage (since the values measured directly on the cell are
not delivered to the module).
AT^SCTM Query temperature range, enable/disable URCs to report critical temperature ranges
AT^SMSO Power down GSM engine
For the GSM engine to change from the Alarm mode to full operation (normal operating
mode) it is necessary to drive the ignition line to ground. This must be implemented in your
host application as described in Chapter 3.3.1.1. If your application is battery powered note
that charging cannot be started while the engine is in Alarm mode, i.e. charging will not
begin even though the charger connects to the POWER line. See also Chapter 3.3.5 which
summarizes the various options of changing the mode of operation.
If your host application uses the SYNC pin to control a status LED as described in Chapter
3.8.2.2, please note that the LED is off while the GSM engine is in Alarm mode.