Reverse Engineering Analysis of the Nokia 3500c as it applies to the SplitScreen Reality

Reverse Engineering Analysis of the Nokia 3500c as it applies to the SplitScreen Reality

By:Adam TylerCarlos Larco

Raju ManthenaJustin Mroczkowski

Introduction

• Our group has chosen a cell phone as the subject of the reverse engineering analysis because it combines a camera, a WiFi/GSM style network, a human interface, and a portable package.

The Nokia 3500c

A simple cell phone that incorporates a camera, a network controller, a user interface, and a small battery powered package.

Organization and Construction

External and Internal organization

Parts ListPart / Task Specifications Comments

Display 128x160 Active Pixels Nokia Proprietary

MCU RAPGSM, BB5.0 ASIC, 1.8V I/O, core < 1.8V

Nokia Proprietary, has specially engineered hardware interfaces

RF transmitter/receiver 8PSK/GMS-K, 86dB Antenna

Nokia Proprietary 128 channel, shift keying transmitter. GSM-K industry specific protocol.

Camera 2.0 Mega Pixel Hardware accelerated.

Memory Internal & uSD Standard CMOS / I2C

Power Regulation RETU / TAHVU Nokia proprietary regulators

Battery BL-4C ION, 860 mAh 3.5-4 hrs talktime.

Display• Will use a breakout

board for initial testing, moving into a custom design for final production.

• Will initially use a capacitive touch screen with equivalent specs.

• Connection will follow Nokia’s design.

MCU (Micro-Controlling Unit)• Nokia uses a custom

designed MCU, the RAPGSM which functions on 1.8V I/O and <1.8V on the core.

• We will use a custom programmed ATMEL or PIC MCU, working in parallel with a XILINX FPGA.

RF Subsystem• The RF subsystem

consists of a specially designed high gain antenna and the GSM modulator / demodulator block utilizing the 8PSK or GSM-K.

• We will use an off the shelf transmitter initially and a custom design later in the production cycle.

Camera• Nokia utilizes a standard

CMOS camera with 2.0 MP and a hardware accelerator which is nothing more than a custom designed control component.

• We will initially utilize a CMOS IC camera to transmit video signals, later replaced by a video port + video filters and interfaces.

Memory• Nokia utilizes a micro

Secure Digital (SD) card for user storage and MCU-internal SDRAM and NOR flash memory.

• We will utilize CMOS ram chips (256Kx8bit words) and a USB connection to a PC for large data operations (and charging).

Power Regulation• The Tahvo and RETU

ASIC (Application Specific Integrated Circuit) are power regulators that take power from the battery/USB and route it to the subsystems.

• We will utilize a DC-DC converter, in the same manner.

Battery• Nokia utilizes a BL-4C

ION, 860 mAh that provides approximately 3.5-4 Hours of talk time.

• We will utilize a variety of sources including Li-ION batteries, USB power, or AC power utilizing transformers via a barrel jack.

Software Analysis-Wifi• A mobile ad-hoc network is an example of a wifi network. However ad-hoc

networks are not based on infrastructure. • A regular WiFi consists of stations which form a base service set. The base

service set consists of one station which acts as an access point. Each base service set is operated by a control function in the MAC (medium access control layer) which tells the stations when to transmit their signals.

• For a WiFi with infrastructure all the nodes must have access to the access point. An ad hoc WiFi network does not have a central access point and instead the nodes relay information through and for their neighbors, allowing for greater organization flexibility.

Software Analysis• The OSI model (Open Systems Interconnection Model), is a model that

describes how two nodes in a network (whatever kind of network it is; wireless or ad hoc) communicate with each other. In order to communicate, each node must abide by certain protocols.

• Protocols are just like the language in the network as a whole understands if it wants to communicate. The OSI is divided into seven layers.

• Starting from the physical layer (this is the hardware regarding how exactly the node captures the signal) to the application layer (this layer is the highest layer which allows a node to send some user defined information from it to another node.)

• The similarity between standard wifi, and ad hoc is that they must pay attention to the interference they get from other nodes transmitting at that same time, therefore they have to abide strictly by the protocols in the Data Link Layer.

Differences between Wifi and Ad-hoc

• The ad-hoc network must use a routing protocol to obtain a route, while in standard wifi, the route is pre-established. The routing protocol that we are using will be an on demand one, which would either be AODV (ADHOC On demand Distance Vector) or DSDV (Destination Sequenced Distance Vector).

• Now the routing tables are maintained in the routing layer of the OSI model, while the routing protocol actually takes place via all the layers including the application layer as the routing packets must be processed by the node.

• In our system, as the nodes will be similar but simple, the need for multiple hardware layers is not present. We are using the paradigm of multiple layers for different parts of the network by creating a header with multiple “flags” or “fields” that indicate the type of packet and indicate to the processor what it should do with the received packet.

Works cited:[1] Nokia Inc, Service Manual. Nokia, 2007, pp 5-1 -- 5-15.

[2] PC Magazine, “ASIC Definition.” [Online]. Available: http://www.pcmag.com/encyclopedia/term/38030/asic

[3] Digilent, “ChipKIT uC32 Protoyping Platform.” [Online]. Available: http://www.digilentinc.com/Products/Detail.cfm?Prod=CHIPKIT-UC32

[4] Digilent, “CoolRunner-II CPLD Starter Board.” [Online]. Available: http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,1000&Prod=CR2-STARTER

[5] Texas Instruments, SN74LVC245A Datasheet, 1993, pp 1-25.

[6] Rabbit Inc, An Introduction to WiFi, 2008.