User Guide

PAMS
Technical Documentation
NSE–8/9
System Module
Page 2– 63
Issue 1 07/99
The Cobba_GJP is a mixed signal IC including the Baseband RF analog
interface and the Baseband audio PCM interface. The Cobba converts the
down link audio PCM stream from the DSP to analog signals feeding the
audio output transducers. The Coba converts the analog audio input from
the microphone devices to an uplink PCM bit stream to be feed to the
DSP for further processing. The MAD a separate pin for resetting the
Cobba.
There are two separate busses between the Cobba and the MAD2PR1:
– The SerRFI bus which is used to control the COBBA device and for trans-
ferring the data to and from the RF. The bus is implemented with 5 lines
– The PCM interface that transfers the PCM coded voice data to and from the
audio CODEC part of the Cobba. The bus contains receive– and transmit–
data, frame synchronization (8KHz) which indicates the rate of the PCM
samples, and the clock (520 KHz). The cobba is generating both clocks from
the 13MHz signal delivered from the MAD.
PData (0 – 4) are logical output ports on the Cobba, controlled by the
DSP. The MCU can control the pins by a MDI message sent to the DSP
(all inside the MAD). The pins are used to:
– interfaces to the UI Switch, with two enable signals for the keyboard and dis-
play back light drivers
– drive the Mute transistor V202 for the external audio PPH–1 Unit
– connection to a test pad J349, SW request for in field debugging possibility
Audio
The Cobba audio interface includes:
– 3 differential microphone inputs (MIC1,MIC2, MIC3). MIC1 and MIC 3 are
connected together and to the bottom connector for handsfree (MIC1) and
headset (MIC3) use. MIC2 is for the internal microphone.
– two differential audio outputs EAR for internal earpiece, and HF/HFCM for
external audio output
– MBias which are used for bias supply for the internal microphone
– Auxout (0V; 1.5V ; 2.1 V or high impedance) are used for bias supply for the
headset microphone, or control voltage for accessory identification
The audio paths and the voltage of Auxout and MBias are selected with
control bits in the audio control register inside Cobba