> 3.5.7 | 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 TC65 is in Power-down mode, TC65 goes into Charge-only mode.
> While the charger remains connected it is not possible to switch the module off by using the AT^SMSO command or the automatic shutdown mechanism. Instead the following applies:

> • | If the module is in Normal mode and the charger is connected (Charge mode) the AT^SMSO command causes the module to shut down shortly and then start into the Charge-only mode.

> • | In Charge-only mode the AT^SMSO command is not usable.

> • | In Charge-only mode the module neither switches off when the battery or the module exceeds the critical limits of overtemperature or undertemperature.

> In these cases you can only switch the module off by disconnecting the charger.
> To proceed from Charge-only mode to another operating mode you have the following options, provided that the battery voltage is at least above the undervoltage threshold.

> • | To switch from Charge-only mode to Normal mode you have two ways:

> - | Hardware driven: The ignition line (IGT) must be pulled low for at least 2 seconds. When released, the IGT line goes high and causes the module to enter the Normal mode.

> - | AT command driven: Set the command AT^SCFG=MEopMode/Airplane,off (please do so although the current status of Airplane mode is already “off”). The module will enter the Normal mode, indicated by the “^SYSSTART” URC.

> • | To switch from Charge-only mode to Airplane mode set the command AT^SCFG=MEop Mode/Airplane,on. The mode is indicated by the URC “^SYSSTART AIRPLANE MODE”.

> • | If AT^SCFG=MEopMode/Airplane/OnStart,on is set, driving the ignition line (IGT) activates the Airplane mode. The mode is indicated by the URC “^SYSSTART AIRPLANE MODE”.

> Table 11: | AT commands available in Charge-only mode

> AT command | Use
> AT+CALA | Set alarm time, configure Airplane mode.
> AT+CCLK | Set date and time of RTC.
> AT^SBC | Query status of charger connection.
> AT^SBV | Monitor supply voltage.
> AT^SCTM | Query temperature range, enable/disable URCs to report critical temperature ranges
> AT^SCFG | Enable/disable parameters MEopMode/Airplane or MEopMode/Airplane/OnStart

> Table 12: | Comparison Charge-only and Charge mode

> 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 TC65 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 inter faces 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 the 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 TC65 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 applica tion is switched off. If the application is fed from the trickle charge current the module might be prevented from pro ceeding to software controlled charging since the current would not be suffi cient. |
> • | 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.