Nokia 9000i, Service Manual

Page: 51 / 434

After Sales
Technical Documentation
RAE/RAK–1N
Baseband
Page 2–25
Original, 08/96
– CTRLU – PWRU
MCU controls the watchdog timer in PSL+. It sends a positive pulse at
approximately 2 Hz to XPWROFF pin of the PSL+ to keep the power on. If
MCU fails to deliver this pulse, the PSL+ will remove power from the
system. MCU also controls the charger on/off switching in the PWRU
block. When power off is requested or MCU leaves PSL+ watchdog
without reset. after the watchdog time has elapsed the PSL+ cuts off the
supply voltages from the phone.
– CTRLU – ASIC
MCU and ASIC have a common 8–bit data bus and a 9–bit address bus.
Bits A(4:0) are used for normal addressing. ASIC controls the main clock,
main reset and interrupts to MCU. The 26 MHz MCUCLK is divided by two
in SCL and the resulting 13 MHz clock is supplied to the MCU. RESETX
resets everything in MCU except the contents of the RAM. IRQX is a
general purpose interrupt request line from ASIC. After IRQX request the
interrupt register of the ASIC is read to find out the reason for interrupt.
NMI is used only to wake up MCU from software standby mode.
– CTRLU – DSPU
MCU and DSP communicate through ASIC. ASIC has an MCU mailbox
and a DSP mailbox. MCU writes data to DSP mailbox where DSP can only
read the incoming data. In MCU mailbox the data transfer direction is the
opposite. When power is switched on the MCU loads data from the flash
memory to DSP‘s external memory through this mailbox.
– CTRLU – AUDIO
When the the chip select signal XSELPCMC goes low, MCU writes or
reads control data to or from the speech codec registers at the rate
defined by PCMCLK. PCMCDI is an output data line from MCU to codec
and PCMCDO is an input data line from codec to MCU. The AMP_PWR
signal is used for switching the Personal Hands–Free amplifier between
On and Standby modes.
– CTRLU – RF/BATTERY Monitoring
MCU has internal 12 channel 10 bit AD converter. Following signals are
used for monitoring battery, charging and RF:
BTYPE battery size
TBAT battery temperature
VBATDET battery voltage
VC charging voltage
TRF RF temperature
– CTRLU – Keyboard and LCD Driver Interface
MCU and User Interface communication is controlled through ASIC.