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Both MAD and CCONT include a watchdog, and both use the 32 kHz sleep clock. The watchdog in MAD is the primary one, and this is called SW-watchdog. MCU has to update it regularly. If it is not updated, logic inside MAD gives reset to mAd. After the reset, MCU can read an internal status bit to see the reason for reset, whether it was from MAD or CCONT. The SW-watchdog delay can be set between 0 and 63 seconds at 250 millisecond steps; and after power-up the default value is the max. time.

MAD must reset CCONT watchdog regularly. CCONT watchdog time can be set through SIO between 0 and 63 seconds at 1 second steps. After power-up the default value is 32 seconds. If watchdog elapses, CCONT will cut off all supply voltages.

After total shut down the phone can be re-started through any normal power-up procedure.

Technical Documentation System Module

Power up

When the battery is connected to the phone, nothing will happen until the power-up procedure is initiated, for instance by pressing the power-button (or by connecting charger voltage). After that the 32kHz crystal oscillator of CCONT is started (can take up to 1 sec), as well as the regulators are powered up.

If power down is done, and the battery remains connected, the 32 kHz crystal oscillator keeps still running in the CCONT. When power-up is initiated again, the complete power-up sequence is described in the figure below. This time the power-up sequence is faster, because the oscillator is already running.

Power up when power-button is pushed

t1 < 1 ms t2 1 - 6 ms, VCXO settled t3 62 ms, PURX delay generated by CCONT

After the PWR-key has been pushed, the CCONT gives PURX reset to the MAD and COBBA, and turns on the VR1, VBB and VR6 regulators (if battery voltage has exceeded 3.0 V). VR1 supplies the VCXO, VBB supplies the MAD and digital parts of the COBBA, and VR6 supplies analog

System Module

Technical Documentation parts of the COBBA and some RF parts. After the initial delay t2 the VCXO starts to give proper RFC to the COBBA that further divides it to COBBACLK for the MAD. The COBBA will output the COBBACLK only after the PURX reset has been removed. After delay t3 the CCONT releases PURX and the MAD can take control of the operation of the phone.

After that the MCU-SW in the MAD detects that the PWR-key is still pushed and shows the user that the phone is powering up by starting the LCD and turning on the lights. The MCU-SW must start also the RF receiver parts at this point.

The CCONT will automatically power-up also the VSIM-regulator (used for possible reFlashing), regardless of the control pin SIMPWR state, and the regulator default voltage is 3V.

The V5V-regulator (for RF) default value is OFF in power-up, and can be controlled to ON via serial bus when needed.

The phone can be powered up by external device (accessory or similar) by providing a start pulse to the battery signal BTEMP; this is detected by the CCONT. After that the power-up procedure is similar to pushing the power-button.

It is possible that the PWR-key is pushed during a charger initiated power-up procedure or that the charger is connected during a PWR-key initiated power up procedure. In this kind of circumstances the power-up procedure (in HW point of view) continues as nothing had happened.

When the Baseband HW is working normally and the SW is running, the SW detects that both conditions are fulfilled and then acts accordingly.

The MAD (MCU SW) detects that the PWR-key is pressed long enough time. After that the lights and LCD are turned off. The MCU stops all the activities it was doing (e.g. ends a call), sends power off command to CCONT (i.e. gives a short watchdog time) and goes to idle-task. After the delay the CCONT cuts all the supply voltages from the phone. Only the 32 kHz sleep clock remains running.

Note that the phone doesn't go to power off (from HW point of view) when the charger is connected and PWR-key is pushed. It is shown to the user that the phone is in power off, but in fact the phone is just acting being powered off (this state is usually called "acting dead" state).

IBI (Intelligent Battery Interface)

Mixed trigger to power up

Power Off

Power off by pushing Power-key

Technical Documentation

System Module

Power off when battery voltage low

During normal discharge the phone indicates the user that the battery will drain after some time. If not recharged, the SW detects that battery voltage is too low and shuts the phone off through a normal power down procedure.

Anyway, if the SW fails to power down the phone, the CCONT resets and powers down the phone if the battery voltage drops below 2.8V.

If the MAD receives fault indication from the line TXF, that the transmitter is on although it shouldn't be, the control SW will power down the phone.

The phone can enter the SLEEP only when both the MCU and DSP request it. A substantial amount of current is saved in the SLEEP. When going to the SLEEP following things happen :

1. Both the MCU and DSP enable sleep mode, set the sleep timer and enter sleep mode

2. RFCEN and RFCSETTLED -> 0 -> COBBACLK will stop (gated in the COBBA). Also VR1 is disabled -> the VCXO supply voltage is cut off -> the RFC stops.

3. LCD display remains the same, no changes

4. Sleep clock (SLCLK) and watchdog in the CCONT running

5. Sleep counter in the MAD running, uses SLCLK

In a typical case the phone leaves the SLEEP-mode when the SLEEP-counter in MAD expires. After that MAD enables VR1 ^ the VCXO starts running ^ after a pre-programmed delay RFCSETTLED rises => the MAD receives COBBACLK clock ^ the MAD operation re-starts.

There are also many other cases when the SLEEP mode can be interrupted, in these cases the MAD enables the VR1 and operation is started similarly

- some MCU or DSP timer expires

- DSP regular event interrupt happens

- MBUS activity is detected

- FBUS activity is detected

- Charger is connected, Charger interrupt to the MAD

- any key on keyboard is pressed, interrupt to the MAD

- HEADSETINT, from system connector XMIC line (EAD)

- HOOKINT, from system connector XEAR line

Power off when fault in transmitter

Sleep Mode

Waking up from Sleep-mode

System Module Technical Documentation

Baseband submodules CTRLU

The CTRLU comprises the MAD ASIC (MCU, DSP, System Logic) and Memories.

The environment consists of three memory circuits (FLASH, SRAM, EE-PROM), a 22-bit address bus and a 8/16-bit data bus. Besides there are ROM1SELX, ROM2SELX, RAMSELX and EEPROMSELX signals for chip selection.

MCU main features

System control

Cellular Software (CS)

The Cellular Software takes care of communication with the switching office, as well call set-up, maintenance and termination.

Communication control

M2BUS is used to communicate with external devices. This interface is also used for testing, service and maintenance purposes.

User Interface (UI)

PWR-key, keyboard, LCD, backlight, mic, ear and alert (buzzer, vibra, led) control. Serial interface from the MAD to the LCD (common for CCONT).


Authentication is used to prevent fraudulent usage of the cellular phone.

RF monitoring

RF temperature monitoring by VCXOTEMP, ADC in CCONT. Received signal strength monitoring by RSSI, ADC in CCONT. False transmission detection by TXF signal, digital IO-pin.

Power up/down and Watchdog control

When the power key is pressed, the initial reset (PURX) has happened and default regulators have powered up in the CCONT, The MCU and DSP take care of the rest of power up procedures (LCD, COBBA, RF). The MCU must regularly reset the Watchdog counter in CCONT, otherwise the power will be switched off.

Accessory monitoring

Accessory detection by EAD (XMIC/HEADSETINT), AD-converter in the CCONT. Connection (FBUS) for data transfer.

Technical Documentation

System Module

Battery and charging monitoring

The MCU reads the battery type (BTYPE), temperature (BTEMP) and voltage (VBAT) values by AD-converter in CCONT, and the phone's operation is allowed only if the values are reasonable. Charging current is controlled by writing suitable values to the PWM control in the CCONT. The MCU reads also the charger voltage (VCHAR) and the charging current values (ICHAR).

Production/after sales tests and tuning

Flash and EEPROM loading, baseband tests, RF tuning

Control of CCONT via serial bus

The MCU writes controls (regulators on/off, Watchdog reset, charge PWM control) and reads the AD-conversion values. For AD-conversions the MCU gives the clock for the CCONT (bus clock), because the only clock in the CCONT is the sleep clock, which has a too low frequency.

The DSP (Digital Signal Processor) is in charge of the channel and speech coding according to the IS-136 specification. The block consists of a DSP and internal ROM and RAM memory. The input clock is 9.72 MHz, and the DSP has its' own internal PLL-multiplier. Main interfaces are to the MCU, and via System Logic to the COBBA and the RF.

- MCU related clocking, timing and interrupts (CTIM)

- DSP related clocking, timing and interrupts (CTID)

- DSP general IO-port

-reset and interrupts to MCU and DSP

- interface between MCU and DSP (API)

- MCU interface to System Logic (MCUif)

- MCU controlled PWMs, general IO-port and USART for MBUS (PUP)

- Receive Modem (Rxmodem)

- Interface to Keyboard, CCONT and LCD Drivers (UIF)

- Interface to MCU memories, address lines and chip select decoding (BUSC)

- DSP interface to System Logic (DSPif)

- serial accessory interface (AccIf, DSP-UART)

- Modulation, transmit filter and serial interface to COBBA (MFI)

- Serial interface for RF synthesizer control (SCU)

DSP main features

System Logic main features


The speed of FLASH and SRAM is 120 ns.

System Module

Technical Documentation

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DIY Battery Repair

DIY Battery Repair

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