Audio; How The Audio Works - Nokia 2255 Baseband Description And Troubleshooting

2255 (RM-97)
Baseband Description and Troubleshooting

Audio

How the Audio Works

The baseband supports three microphone inputs and two ear piece outputs. The
microphone inputs are MIC1, MIC2, and MIC3:
• MIC1 input is used for the mobile terminal's internal microphone
• MIC2 input is used for Universal Headset
• MIC3 input is used for the FM Radio
Every microphone input can have either a differential or single-ended AC connection to
the UEMC circuit. In the Nokia 2255, the internal microphone (MIC1) and external
microphone (MIC2) for UHJ is single-ended. However, the Universal Headset interface is
single-ended. The microphone signals from different sources are connected to separate
inputs at the UEMC. Inputs for the microphone signals are differential types. Also, MICB1
is used for MIC1 and MIC2 uses VFlash1.
Charging jack
Volume keys
Page 12
UHJ MIC3
Figure 9: Audio components
©2005 Nokia Corporation
Earpiece
MIC1
Company Confidential
IHF
ISSUE 1 10/2005