Speech Processing; Alert Signal Generation; Digital Control; Mad2Wd1 - Nokia NSB-5 Series Technical Documentation Manual

NSB-5
System Module
The output for the internal earphone is a dual ended type output capable of driving a
dynamic type speaker. The output for the external accessory and the headset is single
ended with a dedicated signal ground SGND. Input and output signal source selection
and gain control is performed inside the COBBA_GJP asic according to control messages
from the MAD2WD1. Keypad tones, DTMF, and other audio tones are generated and
encoded by the MAD2WD1 and transmitted to the COBBA_GJP for decoding. MAD2WD1
generates two separate PWM outputs, one for a buzzer and one for vibra (internal and
external via BTEMP).

Speech Processing

The speech coding functions are performed by the DSP in the MAD2WD1 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 options for the PCM interface between MAD2WD1 and COBBA_GJP. The
4-pin solution and a 1-pin solution. The four pin serial interface between MAD2WD1 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_GJP generates both clocks. NSB–5 uses the 4–pin solution.

Alert Signal Generation

A buzzer is used for giving alerting tones and/or melodies as a signal of an incoming call.
Also keypress and user function response beeps are generated with the buzzer. The
buzzer is controlled with a BuzzerPWM output signal from the MAD2WD1. A dynamic
type of buzzer is used since the supply voltage available cannot produce the required
sound pressure for a piezo type buzzer. The low impedance buzzer is connected to an
output transistor that gets drive current from the PWM output. The alert volume can be
adjusted either by changing the pulse width causing the level to change or by changing
the frequency to utilize the resonance frequency range of the buzzer.

Digital Control

MAD2WD1

The baseband functions are controlled by the MAD2WD1 ASIC, which consists of a MCU,
a system ASIC, and a DSP. The GSM/PCN-specific ASIC is named MAD2. There are sepa-
rate controller ASICs in TDMA and JDC named MAD1 and MAD3. All the MAD2WD1
ASICs contain the same core processors and similar building blocks, but differ from each
other in system specific functions, pinout, and package types.
• MAD2WD1 contains following building blocks:
• ARM RISC processor with both 16–bit instruction set (THUMB
mode) and 32–bit instruction set (ARM mode)
• TMS320C542 DSP core with peripherials:
– API (Arm Port Interface memory) for MCU–DSP communication,
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Nokia Mobile Phones Ltd.
PAMS Technical Documentation
Issue 1 03/01