NEC DB2000, Service Manual

Page: 29 / 199

Part 6: Logic Circuit Description
This section describes the architecture and hardware functionality of the logic
circuit. The logic circuit performs the following functions:
•
Channel coding/ decoding
•
Speech coding / decoding
•
Data encryption
•
Layer 1,2 and 3 software tasks
•
I/O System interface
•
SIM interface and management
•
Audio and tone control
•
Vibrator control
•
Power supply and battery management
•
RF power control
•
Synchronisation
•
Real time clock
•
Key-Pad control and scanning
•
LCD control and driver
The logic and RF circuits are primarily controlled and administered by two main
devices, these being:-
•
“Superchip”- CSP and DSP Combined (IC27)
The “Superchip” combines the functions of both the CSP and DSP in a single
package. The device performs channel and speech coder/decoder tasks,
equalisation, encryption, frame timing, A/D conversion, RF power control
and audio interfacing, including tone generation.
•
Nell - (IC8)
Nell incorporates the main CPU for the mobile and controls the functions;
Layer 1,2 and 3 software, the SIM, system interfaces, real time clock, buzzer,
vibrator, battery management, Key-Pad scanning and LCD control. Nell also
controls the integrated power supply devices:- “MiniMoe” and “MicroMoe” .
The Logic circuit is divided into six main functional areas:
1) Superchip (CSP and DSP combined)
2) Nell and CPU Memory
3) Battery Interface and Power Supply
4) Keypad, Display and SIM
5) Audio and Miscellaneous Interfaces
6) System Connector - P5