Keyboard; Fig 13 Dc-Out Interface - Nokia RH-9 Series Ccs Technical Documentation

RH-9
System Module & UI
The power part consists of a current limited switch, and is controlled by a logic enable
(on/off) via KLIGHT. On/off is synchronised with "VIBRA" signal SW wise, but can have
independent SW control.

Keyboard

The keyboard used in RH-9 is partly matrix ("metal dome" type) and partly individually
interrupts, this is needed for supporting multiplekeypresses.
The keyboard PWB layout consists of a grounded outer ring and either a "cake pattern"
grid (matrix) or an inner pad. This construction makes the keys immune for ESD, as the
keydome will have a low ohmic contact with the PCB ground
All lines are configured as input, when there is no key pressed, the inputs are high due to
that the UPP has internally pull-up resistors on those lines. When a key is pressed, the
specific lines where the key is placed is pulled low. This generates an interrupt to the
MCU and the MCU now starts its scanning procedure.
Page 42
Figure 14: Keyboard layout
ãNokia Corporation
CCS Technical Documentation
Issue 1 11/02