User Guide

RH-26
2 - System Module CCS Technical Documentation
Page 28 ©Nokia Corporation Issue 1 02/04
quality still image mode. The camera module supports the CCP/CCI interface.
The camera module supports a sleep and shutdown functions in order to minimize the
current consumption when not used.
In viewfinder mode the device outputs RGB 4:4:4 pixel data for the color LCD display.
Keypads
RH-26 consists of a separate flip board, TF6, which includes contacts for the qwerty and
T9 keypad domes, MCU, led driver and LEDs for keypad lighting. The flip board is con-
nected to the main PWB through a 3-pin flip connector interface with coaxial cables.
Signals of the connector are described in section: External signals and connections.
The keyboard of RH-26 consists of qwerty keypads located on the top side of the engine
PWB and the FLIP module.
Keypad signals of the engine qwerty keypad are connected to the UPP keyboard inter-
face. The flip keypad is connected to the MCU located in the flip PWB. Key presses are
sent to engine through a 2-wire serial interface. The implementation of the engine and
flip keypad is similar.
LCD & keyboard illumination
In RH-26, white LEDs are used for LCD and keypad lighting. Three LEDs are used for LCD
lighting and on the engine side eight LEDs for qwerty keypad and soft key lighting. A
step-up DC-DC converter (LM3500) is used as a LED driver. On the flip module, four LEDs
are used for T9 and four LEDs for the qwerty keypad lighting.
LCD LEDs are driven in a serial mode to achieve stable backlight quality. This means con-
stant current flow through LCD LEDs. Serial resistance Rlcd is used to define the proper
current. The feedback signal, FB, is used to control the current. Driver increases or
decreases the output voltage for LEDs in order to keep the current stable.