User Guide

RH-26
2 - System Module CCS Technical Documentation
Page 26 ©Nokia Corporation Issue 1 02/04
to be grounded. The UEMK PWRONX signal is not part of the keypad matrix. The power
key is only connected to the UEMK. This means that when pressing the power key, an
interrupt is generated to the UPP that starts the MCU. The MCU then reads the UEMK
interrupt register and notices that it is a PWRONX interrupt. The MCU now reads the sta-
tus of the PWRONX signal using the UEMK control bus, CBUS. If the PWRONX signal
stays low for a certain time, the MCU accepts this as a valid power on state and contin-
ues with the SW initialization of the baseband. If the power on key does not indicate a
valid power on situation, the MCU powers off the baseband.
Power up when charger is connected
In order to be able to detect and start charging in a case where the main battery is fully
discharged (empty), and hence UEMK has no supply (NO_SUPPLY or BACKUP mode of
UEMK), charging is controlled by the START-UP CHARGING circuitry.
Whenever VBAT level is detected to be below master reset threshold (VMSTR-), charging
is controlled by START_UP charge circuitry. Connecting a charger forces VCHAR input to
rise above charger detection threshold, VCHDET+. Upon detection, start-up charging is
started. UEMK generates 100mA constant output current from the connected charger’s
output voltage. As battery charges, its voltage rises, and when VBAT voltage level is
higher than master reset threshold limit (VMSTR+), charge is terminated.
Charge control block (CHACON) monitors the VBAT voltage level. MSTRX=‘1’ output reset
signal (internal to UEMK) is given to UEMK’s RESET block when VBAT>VMSTR+. UEMK
enters the reset sequence.
If VBAT is detected to fall below VMSTR- during start-up charging, charging is cancelled.
Charging will restart, if new rising edge on VCHAR input is detected (VCHAR rising above
VCHDET+).
Power up when battery is connected
Baseband can be powered up by connecting battery with sufficient voltage. Battery volt-
age has to be over UEMK internal comparator threshold level, Vcoff+. When battery volt-
age is detected, UEMK enters the reset sequence.
Phone can be powered up to LOCAL mode by setting BSI resistor to 3.3kΩ. This causes
MCU to wake up directly when battery voltage is supplied.
RTC alarm power up
If phone is in power off mode when an RTC alarm occurs, the wake up follows the proce-
dure described in section Power up and reset. After baseband is powered on, an interrupt
is given to MCU. When RTC alarm occurs during power on state, the interrupt for MCU is
generated.
A/D channels
The UEMK contains following A/D converter channels that are used for several measure-
ment purposes. The general slow A/D converter is a 10-bit converter using the UEMK
interface clock for the conversion. An interrupt is given at the end of the measurement.