Nokia 6255 Guide

Nokia Customer Care
6255/6255i6256/6256i (RM-19)
Mobile Terminal
Issue 2 05/2005 Company Confidential ©2005 Nokia Corporation
Baseband Description and
Troubleshooting

6255/6255i6256/6256i (RM-19)
Baseband Description and Troubleshooting Nokia Customer Care
Page 2 ©2005 Nokia Corporation Company Confidential Issue 2 05/2005
Contents Page
Introduction ..................................................................................................................................................... 4
Power Up and Reset ....................................................................................................................................6
Power Up - Power Key............................................................................................................................. 8
Power Up - Charger Connection .......................................................................................................... 8
Power Up - RTC Alarm............................................................................................................................. 9
Power Off .......................................................................................................................................................9
Power Consumption and Operation Modes .........................................................................................9
Power-off Mode........................................................................................................................................ 9
Sleep Mode.............................................................................................................................................. 10
Active Mode ............................................................................................................................................ 10
Charging Mode....................................................................................................................................... 10
Power Distribution ....................................................................................................................................11
Clock Distribution ......................................................................................................................................13
RFClk (19.2MHz Analog)...................................................................................................................... 13
RFConvClk (19.2MHz Digital)............................................................................................................. 14
CBUSClk Interface ................................................................................................................................. 15
DBUS Clk Interface................................................................................................................................ 16
SleepCLK (Digital) .................................................................................................................................. 17
SleepCLK (Analog).................................................................................................................................. 18
Flash Programming ...................................................................................................................................18
Connections to Baseband.................................................................................................................... 18
Baseband Power Up .............................................................................................................................. 18
Flash Programming Indication........................................................................................................... 19
Flashing..................................................................................................................................................... 19
Flash Programming Error Codes ........................................................................................................ 22
Charging Operation ...................................................................................................................................24
Battery ...................................................................................................................................................... 24
Charging Circuitry ................................................................................................................................. 24
Charger Detection.................................................................................................................................. 25
Audio .............................................................................................................................................................25
Displays and Keymat ................................................................................................................................25
Main Display............................................................................................................................................ 26
Secondary Display.................................................................................................................................. 27
Keymat...................................................................................................................................................... 27
Camera .........................................................................................................................................................27
DC Measurements.................................................................................................................................. 28
AC Measurements.................................................................................................................................. 28
FM Radio ......................................................................................................................................................29
FM Radio Test ......................................................................................................................................... 29
USB Interface ..............................................................................................................................................31
Accessories ..................................................................................................................................................33
Charging................................................................................................................................................... 34
Pop-port Headset Detection............................................................................................................... 36
FBus Detection........................................................................................................................................ 36
Accessory Detection Through ACI..................................................................................................... 37
RUIM (SIM CAR) ........................................................................................................................................39
Main Display Test Points ........................................................................................................................... 40

Nokia Customer Care Baseband Description and Troubleshooting
6255/6255i6256/6256i (RM-19)
Issue 2 05/2005 ©2005 Nokia Corporation Company Confidential Page 3
Secondary Display Test Points.................................................................................................................. 45
GPS Module .................................................................................................................................................48
Troubleshooting............................................................................................................................................ 49
Mobile Terminal is Totally Dead ............................................................................................................50
Flash Programming Does Not Work .....................................................................................................51
Power Does Not Stay on or the Mobile Terminal is Jammed ........................................................53
Charger Faults ............................................................................................................................................55
Audio Faults ................................................................................................................................................56
Earpiece .................................................................................................................................................... 56
Microphone ............................................................................................................................................. 57
IHF.............................................................................................................................................................. 58
Vibra .......................................................................................................................................................... 59
Display Faults ..............................................................................................................................................60
Main Display............................................................................................................................................ 60
Secondary Display.................................................................................................................................. 62
Keypad Faults .............................................................................................................................................63
Power Key ................................................................................................................................................ 63
UI Modules............................................................................................................................................... 64
EL Panel and Driver ............................................................................................................................... 65
USB ................................................................................................................................................................66
MMC ..............................................................................................................................................................70
FM Radio ......................................................................................................................................................71
Camera .........................................................................................................................................................73
Bluetooth .....................................................................................................................................................73
SIM ................................................................................................................................................................73
GPS ................................................................................................................................................................75

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Baseband Description and Troubleshooting Nokia Customer Care
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Nokia Customer Care Baseband Description and Troubleshooting
6255/6255i6256/6256i (RM-19)
Issue 2 05/2005 ©2005 Nokia Corporation Company Confidential Page 5
Introduction
The 6255/6255i/6256/6256i baseband module is a tri-mode, Code Division Multiple
Access (CDMA), dual-band engine and is based on the DCT4.5 standard. The baseband
engine includes two major Application Specific Integrated Circuits (ASICs):
• D2200 — Universal Energy Management Enhanced Integrated Circuit (UEME IC),
which includes the audio circuits, charge control, and voltage regulators
• D2800 — Main phone processor, which includes system logic for CDMA, two
Digital Signal Processors (DSPs), the Main Control Unit (MCU), and the memory
The BL-6C Li-ion battery is used as the main power source and has a nominal capacity of
1070 mA/h.

6255/6255i6256/6256i (RM-19)
Baseband Description and Troubleshooting Nokia Customer Care
Page 6 ©2005 Nokia Corporation Company Confidential Issue 2 05/2005
Figure 1: Baseband block diagram
PWM
Parallel
Battery Zocus
Sim MMC
Tiku EDGE
MCU ARM925
PDRAM
C-DSP Lead3
A-DSP Lead 3
2G System Logic
UEME
Regulation
Charge Control
Audio
FBUS / MBUS
SIM I/F
RTC
Tomahawk
DC Jack
Int Display
Production
Test IF
RF
Keyboard
Mic
IHF Speaker
Disp BL’s
Camera
IRDA
Bluetooth
FM Radio
Antenna
SMPS
SDRAM
CBUS
Nut
USB
PCM / UART
VCORE
VIO
Regulator
Serial
Ext Display
UHS Jack
EL
Amplifier
EarPiece
Vibra
Cam Flash
PWM
Flash Memory
(Program,
NOR)
Flash Memory
(User, NAND)
D
B
U
S
32 KHz
GPS
19.2 MHz
UART

Nokia Customer Care Baseband Description and Troubleshooting
6255/6255i6256/6256i (RM-19)
Issue 2 05/2005 ©2005 Nokia Corporation Company Confidential Page 7
Power Up and Reset
The UEME ASIC controls the power up and resets. The baseband can be powered up in
the following ways:
• Pressing the Power button, which means grounding the PWRONX pin of the
UEME
• Connecting the charger to the charger input
• Initiating the Real-time Clock (RTC) alarm, when the RTC logic has been
programmed to give an alarm
After receiving one of the above signals (see Figure 2), the UEME counts a 20ms delay
and then enters reset mode. The watchdog and VCORE start, and if the battery voltage
(VBAT) is greater than Vcoff+, a 200ms delay is started to allow references to settle.
After this delay elapses, the VFLASH1 regulator is enabled. Then, 500us later, VR3, VANA,
and VIO are enabled. Finally, the Power Up Reset (PURX) line is held low for 20ms. This
reset (PURX) is fed to the baseband D2800 processor ASIC, which in turn generates resets
for the MCU and the DSP. During this reset phase, the UEME forces the Voltage
Controlled Temperature Controlled Oscillator (VCTCXO) regulator on regardless of the
status of the sleep control input signal to the UEME.
The FLSRSTx from the UEME is used to reset the flash during power up and to put the
flash in power down during sleep mode. All baseband regulators are switched on when
the UEME is powered on.
The UEME internal watchdogs are running during the UEME reset state, with the longest
watchdog time selected. If the watchdog expires, the UEME returns to the power off
state. The UEME watchdogs are internally acknowledged at the rising edge of the PURX
signal to always give the same watchdog response time to the MCU.
The following timing diagram represents the UEME start-up sequence from reset to
power-on mode.

6255/6255i6256/6256i (RM-19)
Baseband Description and Troubleshooting Nokia Customer Care
Page 8 ©2005 Nokia Corporation Company Confidential Issue 2 05/2005
Figure 2: Power-on sequence and timing
Reference signal
PwrOnX
Charger Detection
RTC
UEMRSTX
VCORE
VFlash1
VIO
VANA
VR3
19.2MHz Clk
PURX
t1 t2 t4t3
Sleep Clock
t1 = 20ms
t2 = 200ms
t3 = 500us
t4 = 20ms
Reset mode is entered and
the watchdog starts
End of settling time (only if Vbat > Vcoff+_);
VFLASH1 regulator enabled
VR3, VANA, VIO, and VCORE enabled;
PURX held LOW
D2800 processor, MCU, and DSP are
reset; VCTCXO regulator forced on

Nokia Customer Care Baseband Description and Troubleshooting
6255/6255i6256/6256i (RM-19)
Issue 2 05/2005 ©2005 Nokia Corporation Company Confidential Page 9
Figure 3: Measured power-on sequence and timing
Power Up - Power Key
When the power key is pressed, the UEME enters the power-up sequence. Pressing the
power key grounds the PWRONX pin on the UEME. The UEME PWRONX signal is not part
of the keypad matrix. The power key is only connected to the UEME. When the power key
is pressed, an interrupt is generated to the D2800 processor that starts the MCU. The
MCU then reads the UEME interrupt register through the UEME control bus (CBUS) and
notices that it is a PWRONX interrupt. If the PWRONX signal stays low for a certain time,
the MCU accepts this as a valid power-on state and continues with the SW initialization
of the baseband. If the power key does not indicate a valid power-on situation, the MCU
powers off the baseband.
Power Up - Charger Connection
In order to be able to detect and start charging in cases where the main battery is fully
discharged (empty), charging is controlled by start-up charging circuitry.
The VBAT voltage level is monitored by the Charge Control Block (CHACON) inside the
UEME. When the VBAT level is detected to be below the master reset threshold (VMSTR-),
charging starts. Connecting a charger forces the Charging Voltage (VCHAR) input to rise
above the charger detection threshold (VCHDET+). This causes the UEME to generate

6255/6255i6256/6256i (RM-19)
Baseband Description and Troubleshooting Nokia Customer Care
Page 10 ©2005 Nokia Corporation Company Confidential Issue 2 05/2005
100mA of constant output current from the connected charger’s output voltage. The
battery’s voltage rises at it charges, and when the VBAT voltage level is detected to be
higher than master reset threshold limit (VMSTR+), the start-up charge is terminated.
When VBAT is greater than VMSTR+, the Master Output Reset (MSTRX) signal, which is
internal to the UEME, is set to a Logic 1. This causes the UEME RESET block to enter into
its reset sequence.
If the VBAT is detected to fall below VMSTR- during start-up charging, charging is
cancelled. Charging is restarted when a new rising edge on the VCHAR input is detected
(VCHAR rising above VCHDET+).
Power Up - RTC Alarm
If the mobile terminal is in power-off mode when the RTC alarm activates, a wake-up
procedure occurs. After the baseband is powered on, an interrupt is given to the MCU.
When the RTC alarm occurs during active mode, an interrupt is generated to the MCU.
Power Off
The baseband switches to power-off mode if any of following occurs:
• Power key is pressed
• Battery voltage is too low (VBATT < 3.2V)
• Watchdog timer register expires
The UEME controls the power-down procedure.
Power Consumption and Operation Modes
Power-off Mode
During power-off mode, the power (VBAT) is supplied to the D2800 processor, UEME,
MMC, vibra, LED, PA, and PA drivers. During power-off mode, the UEME leakage current
consumption is approximately 40uA + 15uA from ZOCOS.
Table 1: Power-up Sequence through Charger Detection
Condition Result
VBAT < VMSTR- (start-up charging) Charging starts (VCHAR level begins to rise)
VBAT < VMSTR- (during charging) Charging is cancelled. A new rising edge of VCHAR
(VCHAR > VCHDET+) is required to restart charging
VCHAR > VCHDET+ Battery charges (VCHAR is rising)
VBAT > VMSTR+ Charging ends. MSTRX is set high and the UEME resets.