User's Manual Part 1

MC75 Hardware Interface Description
Strictly confidential / Draft
s
MC75_V00.190a Page 37 of 91 15.02.2005
3.4.5 Operating Modes during Charging
Of course, the battery can be charged regardless of the engine's operating mode. When the
GSM module is in Normal mode (SLEEP, IDLE, TALK, GPRS IDLE or GPRS DATA mode), it
remains operational while charging is in progress (provided that sufficient voltage is applied).
The charging process during the Normal mode is referred to as
Charge mode.
If the charger is connected to the charger input of the external charging circuit and the
module’s VCHARGE pin while MC75 is in Power-down mode, MC75 goes into
Charge-only
mode.
Table 3: Comparison Charge-only and Charge mode
How to activate mode Description of mode
Charge mode
Connect charger to charger input of host
application charging circuit and module’s
VCHARGE pin while MC75 is
• operating, e.g. in IDLE or TALK mode
• in SLEEP mode
• Battery can be charged while GSM module
remains operational and registered to the
GSM network.
• In IDLE and TALK mode, the serial interfaces
are accessible. All AT commands can be
used to full extent.
NOTE: If the module operates at maximum
power level (PCL5) and GPRS Class 12 at the
same time current consumption is higher than the
current supplied by the charger.
Charge-only mode
Connect charger to charger input of host
application charging circuit and module’s
VCHARGE pin while MC75 is
• in Power-down mode
• in Normal mode: Connect charger to
the VCHARGE pin, then enter
AT^SMSO.
NOTE: While trickle charging is in
progress, be sure that the host
application is switched off. If the
application is fed from the trickle charge
current the module might be prevented
from proceeding to software controlled
charging since the current would not be
sufficient.
• Battery can be charged while GSM engine is
deregistered from GSM network.
• Charging runs smoothly due to constant
current consumption.
• The AT interface is accessible and allows to
use the commands listed below.
Table 4: AT commands available in Charge-only mode
AT command Use
AT+CALA Set alarm time
AT+CCLK Set date and time of RTC
AT^SBC Query status of charger connection. Enable / disable “^SBC” URCs.
AT^SCTM Query temperature range, enable/disable URCs to report critical temperature
ranges
AT^SMSO AT^SMSO shuts down the module, but if the charger remains connected the
module will automatically restart into Charge-only mode.