DCP-3 firmware

On this page: Features | Architecture | Interface | Original assets | Battery & charging | Progress & builds

Sisu DCP-3 firmware

DCP-3 is a plain-C firmware for the Rev B2 board. It operates the original Nokia 3210 display and keypad while coordinating a modern cellular modem, audio codec, storage, clock and power system. The user interface is informed by Nokia firmware v6.00, but the implementation is new project code.

What it does

Area	Features
Telephone	Dialling, incoming and outgoing calls, call waiting, call history, phonebook and speed dial
Messages	Reading, writing and saving SMS, long text messages, picture-message encoding and decoding, and voicemail indicators
Personal tools	Clock, alarms, calculator, profiles, settings, tones and composer
Games	Rotation, Snake, Memory, React and Logic, plus a new Pac-Man-style game
Diagnostics	Net Monitor, hardware checks and a USB service console

These features are present in the firmware. See Status for testing on the phone.

Architecture

The RP2354B's two cores share the work. Core 0 handles the applications, storage, clock, I2C devices, USB service interface and modem commands. Core 1 handles audio, including the 16 kHz voice connection between the modem and audio codec.

Settings and local records use CRC-protected two-slot journals in the last 128 KiB of flash. There is no over-the-air firmware updater in the current source.

The recreated interface

The Messages menu, rendered by DCP-3 on a computer and enlarged four times.

Layout, menu language, tones and interaction patterns follow the source phone where the old and new systems agree. Some differences are intentional or unavoidable: LTE signal reporting is not GSM signal reporting, call-divert behavior depends on carrier MMI support, SIM and modem events arrive asynchronously, and engineering pages expose hardware that did not exist in 1999.

Original assets are not distributed

The interface uses fonts, bitmaps, strings and tones derived from the original Nokia firmware. These assets are not distributed with DCP-3. The build instructions explain how to generate them from your own copy.

Battery and charging

Old NiMH packs vary in capacity. The battery gauge measures charge flowing in and out, watches the voltage, and learns from full charge and discharge cycles. It uses that information to estimate the battery bars.

A brief voltage dip during a call should not make the phone decide the pack is empty. The firmware checks whether low voltage persists and compares it with the remaining charge estimate. Low-battery checks begin around 2100 mV, with an empty threshold at 1900 mV.

The firmware can also switch off the charger when the charge target set at the start of a session is reached.

Progress and builds

For results from the phone and the work still ahead, see Status. To explore the source or compile DCP-3, start with Build & availability.