Power Up And Reset - Nokia RM-11 Series Troubleshooting Manual

CC Technical Documentation

Power Up and Reset

Power up and reset is controlled by the UEM ASIC. The baseband can be powered up in
the following ways:
• By the Power button, which means grounding the PWRONX pin of the UEM
• By connecting the charger to the charger input
• By the RTC Alarm, when the RTC logic has been programmed to give an alarm
After receiving one of the above signals, the UEM counts a 20 ms delay and then enters
reset mode. The watchdog starts, and if the battery voltage is greater than Vcoff+, a
200 ms delay is started to allow references to settle. After this delay elapses, the
VFLASH1 regulator is enabled. Then, 500 us later VR3, VANA, VIO, and VCORE are
enabled. Finally, the PURX (Power Up Reset) line is held low for 20 ms. This reset, PURX, is
fed to the baseband ASIC UPP; resets are generated for the MCU and the DSP. During this
reset phase, the UEM forces the VCTCXO regulator on — regardless of the status of the
sleep control input signal — to the UEM. The FLSRSTx from the ASIC is used to reset the
flash during power up and to put the flash in power down during sleep. All baseband
regulators are switched on when the UEM powers on. The UEM internal watchdogs are
running during the UEM reset state, with the longest watchdog time selected. If the
watchdog expires, the UEM returns to power-off state. The UEM watchdogs are
internally acknowledged at the rising edge of the PURX signal in order to always give the
same watchdog response time to the MCU.
The following diagram represents UEM start-up sequence from reset to power-on mode.
Issue 2 09/2005
©2005 Nokia Corporation
Troubleshooting - Baseband
Confidential
RM-11
Page 7