Power Key - Nokia RM-11 Series Troubleshooting Manual

RM-11
Troubleshooting - Baseband

Power Key

When the power on key is pressed, the UEM enters the power up sequence. Pressing the
power key causes the PWRONX pin on the UEM to be grounded. The UEM PWRONX
signal is not part of the keypad matrix. The power key is only connected to the UEM. This
means that when pressing the power key, an interrupt is generated to the UPP that starts
the MCU. The MCU then reads the UEM interrupt register and notices that it is a
PWRONX interrupt. The MCU now reads the status of the PWRONX signal using the UEM
control bus, CBUS. 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 on key does not indicate a valid power on situation the MCU powers off the
baseband.
©2005 Nokia Corporation
Page 10
CC Technical Documentation
Confidential Issue 2 09/2005