SSE-9 hardware

On this page: Dimensions | Main devices | Original parts | LTE bands and radio | Power and charging | Known faults | Rev C

The Rev B2 board

SSE-9 replaces the Nokia 3210's mainboard while keeping its display, keypad, audio parts, battery connections and enclosure. Rev B2 is the current prototype; its dimensions, components and known faults are described below.

Design files and build requirements »

Keypad side of the assembled Rev B2 board.

Dimensions and construction

ITEM	REV B2 DESIGN	SOURCE
Outline	43.87 × 118.22 mm	KiCad edge geometry
Stack	6 copper layers; 1.022 mm nominal	KiCad stack-up
Finish	ENIG specified	Fabrication data
BOM	259 visible symbols; 242 populated; 17 DNP	Rev B2 BOM notes

DNP means deliberately not populated. Check component availability and footprints before ordering parts.

Main devices

RP2354B	Main microcontroller with 2 MiB stacked flash
LE910C1-WWX	Telit cellular module
NAU88C22	Audio codec
TCA8418	Keypad scanner and GPIO expander
LTC2959	Coulomb and power monitor
BQ25171-Q1	Two-cell NiMH charger controller
TPS63020	Buck-boost supply
RV-8803-C7	Real-time clock

What remains original

The assembled prototype uses the donor phone's enclosure, elastomer keypad and contacts, LCD, earpiece, microphone, buzzer, battery springs, charger jack and headset connector geometry. So far, these have been tested together in one handset; other donor parts and accessories still need checking.

Radio and network

The current prototype uses the Telit LE910C1-WWX, an LTE Cat 1 module with VoLTE and SMS over IMS. Other voice-capable variants in the LE910Cx ThreadX family can be used for different regional band sets. The module is chosen when building the board; changing firmware does not add bands to an existing module.

LTE bands by module

Module	Region	LTE bands
LE910C1-WWX Current prototype	Europe, Middle East, Africa, Americas and Asia-Pacific	B1, B2, B3, B4, B5, B7, B8, B8_US, B9, B12, B13, B14, B18, B19, B20, B25, B26, B28
LE910C1-EUX	Europe, Middle East and Africa	B1, B3, B7, B8, B20, B28A
LE910C1-SAX	North America	B2, B4, B12, B66
LE910C1-SNX	North America	B2, B4, B5, B12, B13, B66
LE910C1-NFX	North America	B2, B4, B5, B12, B13, B14, B66, B71

Source: Telit's LE910Cx ThreadX comparison and June 2026 product brief (PDF). B8_US is Telit's band label.

WWX does not include B66 or B71. The table gives the modules' specified bands; the assembled phone has not been tested across every band. WWX is the only variant used in the prototype so far. A different module may need configuration and antenna adjustments.

Choose a variant with voice support. The SAXD, WWXD, SNXD and NFXD versions are data-only, and Telit does not list voice support for INX.

Antenna and carrier compatibility

DCP-3 includes controls for four antenna-tuner states for the Telit module. Antenna tuning is still being worked on, and band coverage and range need further testing.

Network compatibility depends on local frequency bands, carrier provisioning, IMS/VoLTE support, SIM service and antenna performance. The project has no carrier certification. See Status: network tests for the carrier tested so far.

Power and charging

Rev B2 uses the original two-cell NiMH battery format. The LTC2959 measures charge flow, and the BQ25171-Q1 controls charging with an eight-hour hardware safety timer. DCP-3 supervises the battery and charger; its battery algorithm is described on the firmware page.

Known Rev B2 faults

ITEM	WHAT NEEDS FIXING
USB VBUS backfeed	Rev B2 needs a rework to prevent backfeed. Board 1 has this correction; the fabrication archive does not.
Charger enable R77	A rework is required so the charger can recover a deeply discharged battery without relying on the firmware. Board 1 has this correction; the fabrication archive is unchanged.
J2 RF connector	The MHF4L footprint can place one ground terminal on the RF net. This is a board-layout fault, not a firmware issue.
Battery spring	The positive spring can rub solder mask above ground copper. Its clearance needs correcting.
SIM connector	The SIM supply contact may touch the connector shield. This needs checking and correcting on the next board.

Rev B2 needs these corrections before it can be reproduced from the fabrication files.

The published errata describe the rework. Before preparing another board, follow the instructions for choosing the current design files.

Rev C

Plans for the next revision are on Status: what's next.