User's Manual

MC46 Hardware Interface Description
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MC46_HD_V03.05 Page 29 of 99 13.11.2003
3.3.1.3 Turn on MC46 using the POWER signal
As detailed in Chapter 3.5.3, the charging adapter can be connected regardless of the
module’s operating mode (except for Alarm mode).
If the charger is connected to the charger input of the external charging circuit and the
module’s POWER pin while MC46 is off, processor controlled fast charging starts (see
Chapter 3.5.2). MC46 enters a restricted mode, referred to as Charge-only mode where only
the charging algorithm will be launched.
During the Charge-only mode MC46 is neither logged on to the GSM network nor are the
serial interfaces 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 MC46 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 MC46 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 MC46
was powered down by AT^SMSO. Once the alarm is timed out and executed, MC46 enters
into the Alarm mode. This is indicated by an Unsolicited Result Code (URC) which reads:
^SYSSTART ALARM MODE
Note that this URC is the only indication of the Alarm mode and will not appear when
autobauding was activated (due to the missing synchronization between DTE and DCE upon
start-up). Therefore, it is recommended to select a fixed baud rate before using the Alarm
mode. In Alarm mode only a limited number of AT commands is available. For further
instructions refer to the AT Command Set.
Table 5: 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 host application uses the SYNC pin to control a status LED as described in Chapter
3.12.2.2, please note that the LED is off while the GSM engine is in Alarm mode.