Devboard

RP2350B Development Board

Rev 1 — 2026-08-18 · Fabrizio Carlassara · UTN FRA, Departamento de Ingeniería Electrónica, Cátedra de Proyecto Final

KiCad project: devboard.kicad_pro · Schematic: devboard.kicad_sch · PCB: devboard.kicad_pcb

Overview

A minimal development/breakout board built around the Core2350B0 module (an RP2350B‑QFN80 SoM), with a parallel-interface 3.5″ ILI9486 TFT + SD card shield, a rotary encoder for UI input, 8 analog input headers, an I²C header, an SWD debug header, and a selectable power path that can run from USB, an external 5V source/boost module, or a Li‑Po/Li-ion battery.

• Board: 2-layer, 55.45 mm × 64.95 mm
• MCU module: U1 — Core2350B0 (RP2350B in QFN-80), custom project symbol/footprint
• Display: U4 — ILI9486 3.5″ TFT shield (8-bit parallel/8080 interface) with onboard microSD slot (SPI)
• Power: Li‑Po/Li‑ion input, USB VBUS, or external 5V/boost module → selectable VSYS → AMS1117-3.3 → +3V3
• Input: SW1 rotary encoder with integrated push-button

Components

⚠️ U5 and J14 use generic 2.54 mm pin-header footprints as placeholders — U5 is a socket for the plug-in boost module linked above (not a fixed regulator IC on this PCB), and J14 is a bare 2-pin header rather than a JST-PH battery connector. J4 is likewise a standard 2.54 mm SWD header (a schematic note calls it a "JST Debug Connector", but no JST part is actually used).

Power architecture

Battery (Li-Po/Li-ion, ~3.7V) ──► J14 ──► U5 (external boost module) ──► +5V ─┐
                                                                               ├─► JP1 ──► VSYS ──► U2 (AMS1117-3.3) ──► +3V3
                                       USB VBUS (from U1's onboard USB) ──────┘

• JP1 selects what feeds VSYS: bridge pins 1-2 to power VSYS from the external +5V rail (boost module output), or bridge 2-3 to power VSYS from USB VBUS instead.
• VSYS feeds the AMS1117-3.3 (U2), which produces the board's +3V3 rail for the RP2350B and all logic.
• VSYS also feeds the TFT shield's 5V pin directly (U4 pad 19), so the display runs from the ~5V rail while its logic/control lines are driven at 3.3V from the RP2350B GPIOs.
• U1's own USB_DP/USB_DM pins are not routed to this board — the Core2350B0 module has its own USB connector; only its VBUS pin is brought out here for power-source selection.
• U1's RUN, BOOTSEL, 3V3_EN, and ADC_VREF pins are also not routed on this board (available on the module for future use — e.g. reset/BOOTSEL buttons, external ADC reference).

Core2350B0 (RP2350B) pin usage

Connector reference

Open items / things to double check before fabrication

• No charge-management IC for the Li‑Po/Li‑ion battery on J14 — charging must be handled externally.
• Confirm current rating of the boost module against the board's total load (display backlight + MCU) before relying on it.
• GPIO10, 11, 21–26, 28, and 31–39 are unused on this revision — available for future expansion.
• U1's RUN/BOOTSEL are not brought out — flashing relies on the Core2350B0 module's own USB/BOOTSEL, or SWD via J4.