A custom clamshell handheld computer built around the Raspberry Pi Compute Module 5. Minerva combines a gaming-controller form factor with a full Linux environment: dual displays, cellular connectivity, NFC/RFID, and a security-first immutable OS. Every layer of software — compositor, shell, applications — is purpose-built for controller-style interaction.
Device: Minerva | OS: Minerva OS | Desktop Environment: Torchform
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| Torchform shell — home grid, status bar, dock | CM5 carrier board 3D render |
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| Work-in-progress PCB layout (KiCad 9) | DSI/CSI display and camera connectors |
Minerva is not a game console. It is a general-purpose handheld Linux computer designed for an unconventional input paradigm — no keyboard, no precise pointer. The form factor is a direct reference to the New Nintendo 3DS (KTR-001, 2014), matching its footprint almost exactly while adding 8mm of thickness for the CM5 module and a 5000mAh battery.
Core principles:
- The hardware serves the software vision, not the other way around
- Security is structural — immutable root, hardware key storage, physical kill switches
- Minimize runtime overhead across the entire stack (musl libc, Rust binaries, Slint UI)
- Every UI interaction is achievable with the controller alone — no mouse or keyboard assumed
Project-Minerva/
├── Minerva-Hardware/ # KiCad 9 project — CM5 carrier board
│ ├── Minerva-Carrier.kicad_pcb
│ ├── Minerva-Carrier.kicad_sch
│ ├── CM5_GPIO.kicad_sch
│ ├── CM5_HighSpeed.kicad_sch # MIPI DSI, USB 3.0, PCIe
│ ├── PCIe-M2.kicad_sch # M.2 NVMe slot
│ └── Minerva-Carrier.kicad_sym
├── Project-Minerva-OS/ # Rust workspace — OS, compositor, shell
├── Torchform/ # Rust workspace — Desktop Environment
├── Notes/
│ ├── Images/ # Hardware renders, UI screenshots, PCB photos
│ └── minerva-console-hardware-spec-v3.docx
├── Manual/
│ └── WWAN.md # Cellular modem setup guide
├── Docs/ # Component datasheets (EM7565, etc.)
├── rpi-scripts/ # Alpine Linux setup and provisioning scripts
└── CONTEXT.md # Full design reference document
Enclosure CAD is in OnShape (cloud), project name "Project Minerva". Not stored in this repo.
Clamshell handheld. Two shells connected by a friction hinge — holds the lid at any angle, with a 130–140° stop to protect flex cables.
| Dimension | Value |
|---|---|
| Width | 145 mm |
| Depth (closed) | 82 mm |
| Total height (closed) | 30 mm |
| Shell wall thickness | 2 mm |
| Corner roundedness | 30° fillets |
| Reference device | New Nintendo 3DS (KTR-001) |
The lower shell is divided by a central structural spine: battery on the left (~5000mAh LiPo pouch), mainboard electronics on the right. The 3.5" lower touchscreen spans across both zones above the hinge.
| Parameter | Value |
|---|---|
| CPU | ARM Cortex-A76 quad-core, up to 2.4GHz |
| GPU | VideoCore VII — OpenGL ES 3.1, Vulkan 1.2 |
| RAM | 8GB LPDDR4X |
| Storage (eMMC) | 32GB — OS partitions only |
| PCIe | Gen 2 ×1 → NVMe SSD |
| USB | 1× USB 3.0 (WWAN modem) + 1× USB 2.0 (USB-C) |
| Display | 2× MIPI DSI |
| WiFi | 802.11ac dual-band |
| Bluetooth | 5.0 |
Custom 4-layer carrier board. Key design constraints:
- CM5 connector: Hirose DF40C-100DS-0.4V (0.4mm pitch)
- MIPI DSI: 90Ω differential pairs, length-matched, away from switching regulators
- USB 3.0: 90Ω SuperSpeed differential pairs, minimize vias
- PCIe (NVMe): 85Ω differential, AC coupling caps on TX pairs
- RF traces (NFC, WWAN): 50Ω microstrip with clean ground plane
| Layer | Purpose |
|---|---|
| 1 (Top) | Components and signals |
| 2 | Ground plane — unbroken under RF and high-speed |
| 3 | Power planes (3.3V, 1.8V) |
| 4 (Bottom) | Signals, some components |
| Display | Size | Resolution | Interface | Touch |
|---|---|---|---|---|
| Upper (primary) | 5.5" | 1920×1080 | MIPI DSI via hinge FPC | No |
| Lower (companion) | 3.5" | 640×480 | MIPI DSI + I2C touch controller | Yes (capacitive) |
The upper screen is the application viewport. The lower screen is contextual — its content changes based on what is focused on the upper screen (virtual keyboard, radial menus, status info, secondary app views). This is architecturally similar to the Nintendo DS / Wii U GamePad, not a simple extended desktop.
| Input | Type | Interface |
|---|---|---|
| Left pad | Cirque GlidePoint circular capacitive (35–40mm) | SPI0 direct to CM5 |
| Right stick | Hall effect analog (TLV493D / AS5600) | I2C via input MCU |
| D-pad | 4-way digital | Input MCU GPIO |
| A, B, X, Y | Digital face buttons | Input MCU GPIO |
| L1, R1 | Digital shoulder buttons | Input MCU GPIO |
| L2, R2 | Analog triggers | Input MCU ADC |
| Start / Select | Digital | Input MCU GPIO |
| Lower screen | Capacitive touch | I2C touch controller |
A dedicated input MCU (RP2040 or STM32F0) handles button scanning, debouncing, and ADC. The Cirque trackpad connects directly to CM5 SPI0 via the cirque_pinnacle mainline kernel driver.
| Input | Action |
|---|---|
| Left pad (Cirque) | Cursor / navigation |
| D-pad | Spatial focus movement between UI elements |
| A | Confirm / select |
| B | Back / cancel |
| L2 (hold) | App radial menu — layer 1 |
| R2 (hold) | App radial menu — layer 2 |
| L2 + R2 (hold) | Global system radial menu |
| Select | Command palette |
| Start | App switcher |
| L1 / R1 | Switch tiles (split-screen mode) |
| Storage | Use | Encryption |
|---|---|---|
| eMMC 32GB (on CM5) | OS only — immutable boot image | dm-verity (read-only root) |
| M.2 2230 NVMe (PCIe ×1) | All user data | LUKS2 AES-256-XTS, key from ATECC608B |
| Radio | Source | Notes |
|---|---|---|
| WiFi 5 | CM5 onboard | MAC randomization on every association |
| Bluetooth 5.0 | CM5 onboard | BLE + Classic |
| WWAN 5G/LTE | Quectel RM520N-GL or EC25-AF | M.2 B-key, USB 3.0 interface |
| NFC (13.56MHz) | NXP PN7150 (I2C) | MIFARE, ISO 14443, HCE |
| 125kHz RFID | Separate module (EM4100/HID Prox) | On main board |
- Battery: 5000mAh Li-Po single cell
- Charging: USB Power Delivery (5V/3A or 9V/2A fast charge)
- Fuel gauge: BQ27441 or MAX17048 (coulomb counter)
- PMIC: TPS65219 or similar (3.3V, 1.8V, 1.0V rails)
- Clamshell detection: DRV5023 hall effect sensor → suspend on close, wake on open
| Component | Purpose |
|---|---|
| ATECC608B | Hardware secure element — LUKS key derivation, ECDH, HMAC-SHA256, anti-rollback counter |
| Optional: Infineon SLB9670 TPM 2.0 | Measured boot, PCR attestation, key sealing |
Hardware kill switches (physical slide switches, software cannot override):
- Microphone power rail
- Camera power rail (future)
- All radios (WiFi + BT + WWAN) simultaneously
Attaches via FPC or pin header — can be omitted from the base build.
| Component | Chip | Notes |
|---|---|---|
| Sub-1GHz RF | TI CC1101 | 300–928MHz, ASK/OOK/FSK — same IC as Flipper Zero |
| Infrared TX/RX | IR LED + TSOP38238 | NEC, RC5, Sony SIRC, LIRC stack |
| Fingerprint | Goodix GT9368 | libfprint / fprintd, always has PIN fallback |
Base: Alpine Linux, musl libc, OpenRC init system
Rust target: aarch64-unknown-linux-musl
Power on
→ U-Boot (signed, eMMC partition 1)
→ Verify Slot A via dm-verity hash tree
→ Success: Mount read-only rootfs + overlayfs (config partition)
→ OpenRC → derive LUKS key via ATECC608B → unlock NVMe
→ Mount ZFS volumes → Launch Torchform
→ Failure: Boot Slot B recovery
| eMMC Partition | Purpose |
|---|---|
| 1 — Bootloader | U-Boot, signed, read-only |
| 2 — Slot A | Minerva OS verified image (dm-verity, ~4GB) |
| 3 — Slot B | Recovery OS (minimal, read-only, ~2GB) |
| 4 — Boot config | A/B selector, U-Boot environment |
| 5 — Overlay | Writable overlayfs upper layer for /etc |
| NVMe Volume (inside LUKS2) | Mount |
|---|---|
| Home | /home/user |
| Data | /data |
| Logs | /var/log |
| Swap | [swap] |
ZFS is used on the NVMe for snapshots, checksumming, and compression.
| Service | Purpose |
|---|---|
torchform-compositor |
Smithay Wayland compositor (two outputs) |
torchform-inputd |
uinput virtual gamepad + Cirque axis synthesis |
pipewire |
Audio server (replaces PulseAudio) |
NetworkManager |
WiFi, cellular, VPN |
ModemManager |
WWAN modem |
neard / nfcd |
NFC daemon |
whisper.cpp |
On-device speech-to-text (command palette, text fields) |
fprintd |
Fingerprint auth (when daughterboard attached) |
Torchform is a custom Rust DE built entirely for Minerva's controller input paradigm. No GNOME, KDE, or existing DE is used.
See Torchform/TORCHFORM.md for full documentation.
| Layer | Technology |
|---|---|
| UI toolkit | Slint (declarative, Rust-native, CSS-adjacent theming) |
| Compositor | Smithay (Rust Wayland compositor library) |
| Input daemon | Custom torchform-inputd (Cirque SPI, USB HID, uinput) |
| Design tokens | tokens.slint — single source of truth for all theming |
| Crate | Role |
|---|---|
torchform-shell |
Main Slint UI — N3DS chrome, overlays, state machine |
torchform-apps |
All 12 app UI components (embeddable or standalone) |
torchform-compositor |
Smithay two-output compositor, tiling, input |
torchform-inputd |
Cirque SPI, USB HID gamepad, uinput, Unix socket |
torchform-actions |
ShellAction enum + InputMap keybinds (no Slint dep) |
torchform-config |
TorchformConfig TOML loader + settings schema (no Slint dep) |
torchform-settings |
Standalone Settings app |
torchform-files |
Standalone File Browser app |
torchform-terminal |
Writes themed Alacritty/Kitty config then exec()s terminal |
torchform-run |
Sets Wayland env vars then exec()s any app binary |
The shell presents a Nintendo-3DS-style chrome on the upper display:
- Status bar (top, 28px) — workspace dots, clock, battery, now-playing, notifications indicator
- Home screen — 7-app grid + 5-icon dock + search bar
- App window — fullscreen or horizontal split (2 tiles max); no floating windows
- Quick Settings — right-slide panel; sliders + toggle tiles
- Notifications — left-slide panel; notification list
- App Switcher — full-screen card row (Start button)
- Command Palette — searchable command list (X button)
- Radial Menus — primary action pattern; L2/R2 open layers 1/2, L2+R2 opens global system menu
- Hint bar (bottom, 24px) — contextual button hints
The lower companion display shows: virtual keyboard, radial menus, status widgets, app-specific secondary content, or idle status (battery, time, quick toggles).
All apps are Slint + Rust, designed for controller input (no keyboard/mouse assumptions):
| App | Status |
|---|---|
| Settings | Working (schema-driven, sliders/toggles/selects) |
| File Manager | Working (directory navigation, file sizes, icons) |
| Terminal | Working (launches Alacritty or Kitty with themed config) |
| System Monitor | UI ready; backend polling not yet implemented |
| Package Manager | UI ready; backend not yet implemented |
| Log Viewer | UI ready |
| Notes | UI ready |
| Network Manager | UI ready; no backend integration |
| Web Browser | Planned (Servo embedded or Chromium kiosk) |
| Media Player | Planned (mpv backend) |
| Phone / SMS / Email | UI components ready; no backend |
| Camera | Planned (future — hardware not in initial scope) |
App design constraints (all apps must follow):
- No dropdown menus — use enumeration pickers (cycle with A/B or D-pad)
- No text fields requiring a physical keyboard — use voice (Whisper.cpp) or lower-screen virtual keyboard
- UI controls limited to: sliders, checkboxes, enumeration pickers
- Every interactive element reachable by D-pad spatial navigation
- Fullscreen layout (1920×1080 upper screen primary viewport)
- Every app defines what it shows on the lower 3.5" screen
# Build and run the shell emulator (single window with both displays)
cd Torchform
cargo run -p torchform-shell
# Demo modes:
cargo run -p torchform-shell -- --demo radial # radial menu open
cargo run -p torchform-shell -- --demo switcher # app switcher open
cargo run -p torchform-shell -- --demo idle # lower screen idle state
# Two separate windows (mirrors physical layout)
cargo run -p torchform-shell -- --standalone
# Makefile shortcuts:
make run-emulator
make run-standalone
make check # fast type-check (no hardware libs needed)
make build-all # full workspace (needs libseat, libinput, libgbm)Emulator keyboard shortcuts:
| Key | Action |
|---|---|
| Space | Select / go home |
| Enter | Start / app switcher |
| Tab (hold/release) | L2 — radial menu |
| Esc | B — back/cancel |
| A | A — confirm |
| X | Command palette |
| Z | Quick Settings |
| C | Notifications |
| Arrow keys | D-pad |
| I / J / K / L | Analog stick N/W/S/E |
System dependencies (Debian/Ubuntu):
sudo apt-get install \
libseat-dev libinput-dev libgbm-dev libdrm-dev \
libudev-dev libxkbcommon-dev libwayland-dev \
libx11-dev libx11-xcb-dev libevdev-dev \
pkg-config build-essentialSee Project-Minerva-OS/README.md for full build documentation.
cd Project-Minerva-OS
make build # cross-compile all crates for ARM64
make image # build full disk image
make run # test in QEMU ARM64
make deploy-bins # push updated binaries to CM5 over SSH| Subsystem | Status |
|---|---|
| Carrier board schematic | In progress |
| Carrier board PCB layout | In progress — diff pair routing active |
| Enclosure CAD (OnShape) | In progress |
| Torchform shell emulator | Working — run make run-emulator |
| Radial menu UI | Working |
| Command palette UI | Working |
| App switcher UI | Working (display only) |
| Settings app | Working |
| File manager | Working |
Input virtualization (ShellAction + InputMap) |
Working |
| Wayland compositor (Winit backend) | Working |
| Wayland compositor (DRM/KMS) | Stub — pending hardware |
| Input daemon (Cirque SPI) | Written — requires CM5 hardware |
| System actions (brightness, volume, WiFi) | UI complete; no backend syscalls |
| App switcher close/switch logic | Not yet implemented |
| Sysmon, Pkgman, Logview backends | Not yet implemented |
| Phone / SMS / Email backends | Not yet implemented |
| Alpine OS image build | In progress |
| LUKS + ATECC608B key derivation | Design complete |
Hardware:
- Cirque trackpad: TM035035 (35mm) vs TM040040 (40mm) — depends on physical fit
- L2/R2 analog vs digital triggers — analog preferred for gaming, adds ADC complexity
- Fan vs passive cooling — thermal testing needed with CM5 under load
- Input MCU: RP2040 vs STM32F0 (RP2040 cheaper + USB HID; STM32F0 has better ADC)
- Daughterboard connector: FPC vs pin header
Software:
6. App sandboxing model: containers (LXC/Podman) vs Wayland-only isolation vs seccomp-bpf vs hybrid
7. Workspace persistence: how workspace.toml files are managed and discovered
8. OS update mechanism: how Slot A images are built, signed, and deployed (OTA vs USB flash)
9. Whisper.cpp model size: tiny / base / small (accuracy vs CPU tradeoff on CM5)
10. Lower screen display server: distinct Wayland output vs managed Slint surfaces
- CONTEXT.md — full design reference (physical, hardware, OS, DE)
- Torchform/TORCHFORM.md — Torchform DE documentation
- Torchform/CLAUDE.md — Torchform Claude context (architecture deep-dive)
- Manual/WWAN.md — Cellular modem setup
- Docs/ — Component datasheets