User Guide

PAMS Technical Documentation System Module

NSB-5

Issue 1 03/01 Nokia Mobile Phones Ltd. Page 33

External accessory notices powered–up phone by detecting voltage in XMIC line. In

Table 9 there is a truth table for detection signals.

Internal Audio Connections

The speech coding functions are performed by the DSP in the MAD2 and the coded

speech blocks are transferred to the COBBA–GJP for digital to analog conversion, down

link direction. In the up link direction the PCM coded speech blocks are read from the

COBBA–GJP by the DSP.

There are two separate interfaces between MAD2 and COBBA–GJP: a parallel bus and a

serial bus. The parallel bus has 12 data bits, 4 address bits, read and write strobes, and a

data available strobe. The parallel interface is used to transfer all the COBBA–GJP control

information (both the RFI part and the audio part) and the transmit and receive samples.

The serial interface between MAD2 and COBBA–GJP includes transmit and receive data,

clock and frame synchronization signals. It is used to transfer the PCM samples. The

frame synchronization frequency is 8 kHz which indicates the rate of the PCM samples

and the clock frequency is 1 MHz. COBBA is generating both clocks.

4–wire PCM Serial Interface

The interface consists of following signals: a PCM codec master clock (PCMDClk), a

frame synchronization signal to DSP (PCMSClk), a codec transmit data line (PCMTX), and

a codec receive data line (PCMRX). The COBBA–GJP generates the PCMDClk clock, which

is supplied to DSP SIO. The COBBA–GJP also generates the PCMSClk signal to DSP by

dividing the PCMDClk. The PCMDClk frequency is 1.000 MHz and is generated by dividing

the RFIClk 13 MHz by 13. The COBBA–GJP further divides the PCMDClk by 125 to get a

PCMSClk signal, 8.0 kHz.

Table 9: HookDet/HeadDet Detection Truth Table

Accessory connected HookDet HeadDet Notes

No accessory connected High HIgh Pull-ups in the transceiver

Headset HDC-9 with a button

switch pressed

Low Low XEAR and XMIC loaded (dc)

Headset HDC-9 with a button

switch released

High Low *) XEAR unloaded (dc)

Handsfree (HFU-1) Low High XEAR loaded (dc)

LSB

PCMDClk

PCMSClk

PCMTxData

PCMRxData

MSB

15 14 13 12 011 10

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