Whenever the user touches the touch screen, the controller raises an interrupt to RAPU which initiates I2C
transactions to identify the locations the user touches on the display.
Figure 52 Touch system block diagram
Proximity sensor and ambient light sensor
This phone uses a combined proximity and ambient light sensor called DiPro.
The proximity part of the device uses an external IR LED supplied by VBAT. The current this LED consumes is
controlled by DiPro and set using software. The interrupt output of DiPro changes state when the infra red
light from the LED is reflected back by a suitable reflective surface.
Note that when proximity is in use, during a voice call, the proximity sensor detects face and turns off the
display and touch to prevent false key pressing.
The ambient light sensor detects the level of ambient light and adjusts the display and key brightness
accordingly whenever the display is active. Covering this sensor results in dimmed display and key lights.
Figure 53 Proximity sensor and ALS
RM-626
System Module
Issue 1
COMPANY CONFIDENTIAL
Page 6 – 21
Copyright © 2011 Nokia. All rights reserved.
