Watchdogs
There are three watchdogs in UEME. The first one is for controlling system power-on and power-down
sequences. The initial time for this watchdog after reset is 32 s and the watchdog can not be disabled. The time
can be set using a register. This watchdog is used for powering the system off in a controlled manner. The other
one is for security block and is used during IMEI code setting. The third one is a power key watchdog. It is used
to power off the system in case SW is stuck and the user presses the power key. This WD is SW configurable.
Charging
Charging control and charge switch is in UEME. There are two different charging modes; charging an empty
battery (start-up charge mode), and SW controlled charging.
UEME digital part takes care of charger detection (generates interrupt to UPP_WD2), pulse width modulated
charging control (for internal charge switch) and over voltage and current detection. SW using registers controls
all these.
Chargers
RM-25 BB supports a standard charger (two wires); ACP-12 and cigarette charger LCH-12 officially.
Battery
RM-25 battery is a detachable, semi-fixed lithium-Ion BL-4C battery. The nominal voltage is thus 3.7 V (max
charging voltage 4.2 V).
The interface consists of three pins: VBAT, GND and BSI. A pull-down resistor inside the batteries (BSI signal)
recognizes the battery types. The voltage level at BSI line is measured using UEME's AD-converter.
Back-up battery and real time clock
The real time clock (RTC), crystal oscillator and back-up battery circuitry reside in UEME. A register in UEME controls
back-up battery charging and charging is possible only in POWER_ON State.
Baseband measurement A/D converter
UEME contains an 11 channels A/D converter, which is used for different baseband measurement purposes. The
resolution of the A/D converter is 10 bits. The converter uses the CBUS interface clock signal for the conversion.
An interrupt will be given to the MCU at the end of the measurements. The converter is used for following
purposes.
• VBATADC, battery voltage
• BSI, in RM-25 this input is connected to ACI bus and the BSI_PULS. The BSI_PULS is delivered by the flashing
equipment when flashing the phone.
• BTEMP, battery temp
• PATEMP, power amplifier temp
• VCXOTEMP, oscilaotor temp
• Headint
• Hookint
• ALCO/LS, in RM-25 this input is used to determine the value of the BSI resisor of the Battery and thus the
battery type (and local, test modes)
• Headint2, not supported by SW, not used
• AuxDet, not used
• VBACK, test the voltage of backup battery
RM-25
Nokia Customer Care
System module
Page 9–10
Company Confidential
9235618 (Issue 2)
Copyright ©2005 Nokia. All Rights Reserved.