Display And Keyboard; Accessory - Nokia NPD-4 Series Troubleshooting - Bb

NPD-4
Troubleshooting — BB
microphone input can have either a differential or single-ended AC connection to UEM
circuit. The internal microphone (MIC1) and MIC2 are differential and MIC3 microphone
is single-ended. The microphone signals from different sources are connected to separate
inputs at UEM. Inputs for the microphone signals are differential type. Also, MICBIAS1 is
used for MIC1 and MICBIAS2 is used for MIC2 and MIC3.
The HF single-ended output is sent to the input of the MIDI audio amplifier. The amplifier
can be enabled/disabled by GenIO(28). The gain of the amplifier is about 20dB.

Display and Keyboard

LEDs are used for LCD and keypad illumination. There are four LEDs for LCD and two LEDs
for the keypad.
Gray-scale LCD is used. Interface uses 9-bit data transfer. The interface is quite similar to
DCT3-type interface, except Command/Data information is transferred together with the
data. D/C bit set during each transmitted byte by MCU SW.
The following figure is the waveform for LCD interface.

Accessory

Differential-ended external audio accessory connection is supported. Headset and data
Page 22
Figure 17: LCD Interface
Nokia Corporation
CCS Technical Documentation
Confidential Issue 1 02/2003