The baseband is powered up by:
1. Pressing the power key, that generates a PWRONX interrupt signal from the power key to the CCONT, which starts the power up procedure.
2. Connecting a charger to the phone. The CCONT recognizes the charger from the VCHAR voltage and starts the power up procedure.
Before battery voltage voltage rises over 3.0 V Charging Logic gives an initial charge (with limited current) to the battery. After battery voltage reaches that voltage limit the power up procedure is as described in the previous chapters.
3. A RTC interrupt. If the real time clock is set to alarm and the phone is switched off, the RTC generates an interrupt signal, when the alarm is gone off. The RTC interrupt signal is connected to the PWRONX line to give a power on signal to the CCONT just like the power key.
4. A battery interrupt. Intelligent battery packs have a possibility to power up the phone. When the battery gives a short (10ms) voltage pulse through the BTEMP pin, the CCONT wakes up and starts the power on procedure.
When the CCONT is activated, it switches on the baseband supply voltage and generates a power up reset signal PURX to the MAD. When the PURX reset is released, the Mad releases the system reset ExtSysReset and the internal MCUResetX signals and starts the boot program execution. If booting is succeeded program execution continues from flash program memory. When the phone is powered up with an empty battery pack using the standard charger, the charger may not supply enough current for standard power-up procedure and the power-up must be delayed.
If the phone is off when the charger is connected, the phone is powered on but enters a state called "acting dead". To the user the phone acts as if it was switched off. A battery charging alert is given and/or a battery charging indication on the display is shown to acknowledge the user that the battery is being charged.
In the active mode the phone is in normal operation, scanning for channels, listening to a base station, transmitting and processing information. All the CCONT regulators are operating. There are several substates in the active mode depending on if the phone is in burst reception, burst transmission, if DSP is working etc..
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