Nokia 6255 Service Manual 09rm19bb

Nokia Customer Care

6255/6255i6256/6256i (RM-19)

Mobile Terminal

Baseband Description and

Troubleshooting

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

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.......................................................................................................................

Pop-port Headset Detection............................................................................................................... 36

FBus Detection........................................................................................................................................ 36

Accessory Detection Through ACI..................................................................................................... 37

RUIM (SIM CAR) ........................................................................................................................................39

Main Display Test Points ........................................................................................................................... 40

............................ 34

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Nokia Customer Care Baseband Description and Troubleshooting

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

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

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6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

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

Battery

UHS Jack

DC Jack

Tomahawk

Antenna

Bluetooth

GPS

FM Radio

Zocus

Nut

USB

CBUS

PCM / UART

UART

19.2 MHz

VIO

Production Test IF

UEME

Tiku EDGE

Sim

Regulation

Charge Control

Audio

FBUS / MBUS

SIM I/F

RTC

D B U S

MCU ARM925

PDRAM

MMC

32 KHz

Amplifier

PWM

Parallel

Serial

Regulator

Mic

IHF Speaker

EarPiece

Vibra

Disp BL’s

Cam Flash

Int Display

Ext Display

Flash Memory (Program, NOR)

SDRAM

Flash Memory (User, NAND)

VCORE SMPS

C-DSP Lead3

A-DSP Lead 3

2G System Logic

Figure 1: Baseband block diagram

Keyboard

Camera

IRDA

6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

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

Reference signal

PwrOnX

Charger Detection

RTC

UEMRSTX

VCORE

VFlash1

VIO

VANA

VR3

19.2MHz Clk

PURX

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

Sleep Clock

t1 t2 t4t3

t1 = 20ms

t2 = 200ms

t3 = 500us

t4 = 20ms

Figure 2: Power-on sequence and timing

6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

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 (V

charging starts. Connecting a charger forces the Charging Voltage (VCHAR) input to rise above the charger detection threshold (VCH

). This causes the UEME to generate

DET+

MSTR-

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

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 (V

), the start-up charge is terminated.

MSTR+

When VBAT is greater than V 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 V cancelled. Charging is restarted when a new rising edge on the VCHAR input is detected

(VCHAR rising above VCH

Condition Result

VBAT < V

VCHAR > VCH

VBAT > V

(start-up charging) Charging starts (VCHAR level begins to rise)

MSTR-

DET+

MSTR+

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.

, the Master Output Reset (MSTRX) signal, which is

MSTR+

during start-up charging, charging is

MSTR-

DET+

Table 1: Power-up Sequence through Charger Detection

(during charging) Charging is cancelled. A new rising edge of VCHAR

(VCHAR > VCH

Battery charges (VCHAR is rising)

Charging ends. MSTRX is set high and the UEME resets.

) is required to restart charging

DET+

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.

6255/6255i6256/6256i (RM-19)

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Sleep Mode

When the SLEEPX signal is detected low by the UEME, the mobile terminal enters sleep mode. In sleep mode, both processors (MCU and DSP) are in stand-by mode. The mobile terminal enters sleep mode only when both processors make this request. The following processes occur during sleep mode:

• VIO and VFLASH1 regulators are put into low quiescent current mode

• VCORE enters LDO mode

• VANA and VFLASH2 regulators are disabled

• All RF regulators are disabled

• VCTCXO (19.2MHz clock) is shut down

• 32kHz sleep clock oscillator is used as the baseband reference clock

The average current consumption of the mobile terminal in this mode can vary depending on the software state (e.g., slot cycle 0,1, or 2, and if the mobile terminal is working on IS95 or IS2000 for CDMA). However, on average the current consumption is about 1.3mA in sleep mode and 100mA in active mode.

Sleep mode is exited either by the expiration of a sleep clock counter in the UEME or by some external interrupt (e.g., charger connection, key press, headset connection). Any of these conditions cause a high SLEEPX signal, which is detected by the UEME, and causes the mobile terminal to enter active mode where all functions are activated.

Active Mode

During active mode, the mobile terminal is in normal operation, scanning for channels, listening to a base station, transmitting and processing information. There are several sub-states in the active mode depending on the mobile terminal present state of the mobile terminal, such as burst reception, burst transmission, if the DSP is working, etc.

In active mode, software controls the UEME radio frequency (RF) regulators (VR1A and VR1B), which can be enabled or disabled. These regulators work via the UEME charge pump. VSIM can be enabled or disabled, and its output voltage can be programmed to be

1.8V or 3.0V. VR2 and VR4—VR7 can be enabled, disabled, or forced into low quiescent current mode. VR3 is always enabled in active mode, disabled during sleep mode, and cannot be controlled by the software in the same way as the other regulators. VR3 only turns off if both processors (DSP and MCU) request to be in sleep mode.

Charging Mode

Charging mode can be performed in parallel with any other operating mode. A BSI resistor inside the battery indicates the battery type and size and corresponds to a specific battery capacity.

The battery voltage, temperature, size, and charging current are measured by the UEME and controlled by the Energy Management (EM) charging algorithm.

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

The charging control circuitry (CHACON) inside the UEME controls the charging current delivered from the charger to the battery. The battery voltage rise is limited by turning the UEME switch off when the battery voltage has reached 4.2V. The charging current is monitored by measuring the voltage drop across a 220mOhm resistor.

Power Distribution

In normal operation, the baseband is powered from the mobile terminal‘s battery. The battery consists of one Lithium-Ion cell capacity of 1070 mAh and some safety and protection circuits to prevent harm to the battery.

The UEME ASIC controls the power distribution to the entire mobile terminal through the BB and RF regulators. The battery feeds power directly to the following parts of the system:

•UEME

•PA

•Vibra

• Display lights

• Keyboard lights

The heart of the power distribution to the mobile terminal is the UEME. The UEME includes all the voltage regulators and feeds the power to the system. The UEME handles hardware power-up functions so the regulators are not powered and the power-up reset (PURX) is not released if the battery voltage is less than 2.8V.

The baseband is powered from five different UEME regulators (see Table 2):

Table 2: Baseband Regulators

Regulator

VCORE DC/DC

VIO 150 1.8 Enabled always except during power-off mode

VFLASH1 70 2.78 Enabled always except during power-off mode

Maximum Current (mA)

300 1.35 The power-up default value is 1.35V. The output voltage is

Vout (V) Notes

selectable: 1.0V/1.3V/1.5V/1.8V. (Note: If using D2800 processor version 1, the default is

1.57V.)

VFLASH2 40 2.78 Enabled only when data cable is connected

VANA 80 2.78 Enabled only when the system is awake (off during sleep and

power-off modes)

VSIM 25 3.0 Enabled during power-up mode and scanning for a SIM card

6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

Table 3 includes the UEME RF regulators.

Table 3: RF Regulators

Regulator

VR1A 10 4.75 Enabled when cell receiver is on

VR1B 10 4.75 Enabled when the transmitter is on

VR2 100 2.78 Enabled when the transmitter is on

VR3 20 2.78 Enabled when SleepX is high

VR4 50 2.78 Enabled when the receiver is on

VR5 50 2.78 Enabled when the receiver is on

VR6 50 2.78 Enabled when the transmitter is on

VR7 45 2.78 Enabled when the receiver is on

Maximum Current (mA)

Vout (V) Notes

The charge pump that is used by VR1A is constructed around the UEME. The charge pump works with the 1.2MHz clock (CBUS) oscillator and gives a 4.75V regulated output voltage to the RF.

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

Clock Distribution

RFClk (19.2MHz Analog)

The main clock signal for the baseband is generated from the voltage-controlled temperature-controlled crystal oscillator (VCTCXO). This 19.2MHz clock signal is generated by the radio frequency circuitry and fed to the radio frequency clock (RFCLK) pin of the D2800 processor. The 19.2MHz clock can be stopped during sleep mode by disabling the UEME regulator output (VR3), which in turn powers off the VCTCXO.

Figure 4: Waveform of the 19.2MHz clock (VCTCXO)

6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

RFConvClk (19.2MHz Digital)

The D2800 processor distributes the 19.2MHz clock to the internal processors (the DSP and MCU) where the software multiplies this clock by seven (=134.4MHz) for the DSP and by two (=38.4MHz) for the MCU.

Figure 5: RFCovCLk waveform

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

CBUSClk Interface

CBUS utilizes a 1.2MHz clock signal, which is used by the MCU to transfer data between the UEME and the D2800 processor.

Figure 6: CBUS data transfer

6255/6255i6256/6256i (RM-19)

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DBUS Clk Interface

DBUS utilizes a 9.6MHz clock signal, which is used by the DSP to transfer data between the UEME and the D2800 processor.

Figure 7: DBUS data transfer

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

SleepCLK (Digital)

The UEME provides a 32kHz sleep clock for internal use and also to the D2800 processor, where it is used for the sleep-mode timing.

Figure 8: 32 kHz Digital output from UEME

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SleepCLK (Analog)

When the system enters sleep mode or power-off mode, the external 32KHz crystal provides a reference to the UEME. The RTC circuit also uses this clock to turn on the mobile terminal during power-off or sleep mode.

Figure 9: 32KHz analog waveform at 32KHz crystal input

Flash Programming

Connections to Baseband

The flash programming equipment is connected to the baseband using test pads for galvanic connection. The test pads are allocated in such a way that they can be accessed when the mobile terminal is already assembled. The flash programming interface includes the VPP, FBUSTX, FBUSRX, MBUS, and BSI signals, which are used by the FLS-8 for flashing. The connection is through the UEME, which means that the logic voltage levels of these signals correspond to 2.78V. Power is supplied to the mobile terminal using the battery contacts.

Baseband Power Up

The baseband power is controlled by the flash prommer in production and in re-programming situations. The baseband powers up by applying supply voltage to the battery terminals. After the baseband is powered up, flash programming indication begins (see the following "Flash Programming Indication" section).

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

Flash Programming Indication

After connecting the flash prommer to the mobile terminal, the flash prommer sets the MBUS line low to notify the MCU that the flash prommer is connected. This causes the UEME reset state machine to perform a reset to the system by setting the PURX signal low for 20ms.

During flash programming, the MBUS signal transmitted from the UEME to the flash prommer is used as the clock for synchronous communication. This MBUS clock is also supplied by the UEME to the D2800 processor, along with the MBUSRX signal. If the MBUSRX signal is low, the MCU enters flash programming mode. To avoid accidental entry into flash-programming mode, the MCU waits to get input data from the flash prommer. If the timer expires without any data being received, the MCU continues the boot sequence.

When the mobile terminal has entered flash programming mode, the flash prommer writes an 8-bit password to the UEME to indicate that flash programming/ reprogramming is to take place. This 8-bit data is transmitted through the FBUSRX line into a shift register inside the UEME. When the 8 bits have been shifted into the register, the flash prommer generates a falling edge on the BSI line. This loads the shift register content into a comparison register inside the UEME. If the 8 bits in the comparison register matches the default value preset in the UEME, programming starts.

Flashing

In order to avoid spurious loading of the register, the BSI signal is gated during UEME master reset and during power up when the PURX is active (low). The BSI signal must not change states during normal operation unless the battery is extracted. If the battery is extracted, the BSI signal is pulled high.

Note: A falling edge is required to load the comparison register.

The UEME flash programming mode is valid until the MCU sets a bit in the UEME register that indicates the end of flash programming. Setting this bit also clears the comparison register in the UEME previously loaded at the falling edge of the BSI signal. During the flash programming mode, the UEME watchdogs are disabled. Setting the bit indicating the end of flash programming enables and resets the UEME watchdog timer to its default value. Clearing the flash programming bit also causes the UEME to generate a reset to the D2800 processor.

Flash programming is done through the VPP, FBUSTX, FBUSRX, MBUS, and BSI signals.

When the mobile terminal enters flash programming mode, the prommer indicates that flash programming will take place by writing an 8-bit password to the UEME. The prommer sets the BSI value to “1” and then uses FBUSRX for writing and MBUS for clocking. The BSI is then set back to “0”.

The MCU uses the FBUSTX signal to indicates to the prommer that it has been noticed. After this, the MCU reports the ID type to the D2800 processor and is ready to receive the secondary boot code to its internal SRAM.

6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

FLASH_1

CH1 = BSI CH2 = MBUS CH3 = FBUSTX CH4 = FBUSRX

Measure points Production test pattern (J396)

Figure 10: Flashing starts by BSI being pulled up and password being sent to UEME

This boot code asks the MCU to report the mobile terminal’s configuration information to the prommer, including the flash device type. The prommer can then select and send the algorithm code to the MCU SRAM and SRAM/Flash self-tests can be executed.

6255/6255i6256/6256i (RM-19) Baseband Description and Troubleshooting Nokia Customer Care

FLASH_2

CH1 = PURX CH2 = MBUS CH3 = FBUSTX CH4 = FBUSRX

Measure points Production test pattern (J396)

Figure 11: Flashing, continued

• Ch1= PURX

• Ch2 = MBUS toggled three times for MCU initialization

• Ch3 = FBUS_TX low, MCU indicates that prommer has been noticed

• Ch4 = FBUS_RX

6255/6255i6256/6256i (RM-19)

Nokia Customer Care Baseband Description and Troubleshooting

FLASH_3

CH1 = PURX CH2 = MBUS CH3 = FBUSTX CH4 = FBUSRX

Measure points Produ ction test pattern (J396)

Data transfer has started (Fbus_Rx)

Figure 12: Flashing, continued 2

Flash Programming Error Codes

The following characteristics apply to the information in Table 4.

• Error codes can be seen from the test results or from Phoenix's flash-tool.

• Underlined information means that the connection under consideration is being used for the first time.

Table 4: Flash Programming Error Codes

Error Description Not Working Properly

C101 "The Phone does not set FbusTx line high after

the startup."

C102 "The Phone does not set FbusTx line low after

the line has been high. The Prommer generates this error also when the Phone is not connected to the Prommer."

Vflash1 VBatt BSI and FbusRX from prommer to UEME. FbusTx from UPP->UEME->Prommer(SA0)

PURX(also to Safari) VR3 Rfclock(VCTCXO->Safari->UPP) Mbus from Prommer->UEME>UPP(MbusRx)(SA0) FbusTx from UPP->UEME->Prommer(SA1) BSI and FbusRX from prommer to UEME.

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