a2picoFN: Apple II SmartPort Wi-Fi Bridge for FujiNet

Warning

Active Development / Work in Progress This project is currently under active development. Architecture, configuration methods, and firmware features are subject to rapid iteration and changes.

a2picoFN is an Apple II expansion card firmware that integrates FujiNet functionality using Raspberry Pi Pico 2 W microcontrollers (RP2350). It emulates a SmartPort interface card on the Apple II bus and bridges storage and network requests to FujiNet-PC over a transparent Wi-Fi TCP streaming connection using the standard SLIP protocol.

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Overview

a2picoFN bridges the classic Apple II bus to the modern FujiNet ecosystem wirelessly:

• Dual-Core Task Separation:
  • Core 1 (Apple II Bus Frontend): Responds in real-time to Apple II slot access ($Cn00, $C800-$CFFF, SmartPort registers) with sub-microsecond latency, building on low-level PIO bus interfacing from a2pico.
  • Core 0 (Wi-Fi Transport & Protocol Bridge): Drives the CYW43 Wi-Fi stack (lwIP raw polling), runs an on-chip TCP server (port 1985), and handles transparent SLIP framing directly with FujiNet-PC.
• Target Hardware:
  • Raspberry Pi Pico 2 W (RP2350A + CYW43439), tested on A2Pico2Lite W.

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Tested Environment

Hardware verification and testing have been performed using specific, fixed versions of FujiNet components (pinned versions rather than rolling latest builds):

• Host Machine: Apple IIe enhanced
• FujiNet Firmware (fujinet-pc): v1.5.1+git-3d8
• CONFIG Program: 031e086*

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Configuration

FujiNet-PC Setup (fnconfig.ini)

a2picoFN operates as a TCP server listening on port 1985. Configure fujinet-pc to connect to a2picoFN by adding or updating the following section in fnconfig.ini:

[BOIP]
enabled=1
host=<a2picoFN_IP_address>

Apple II Wi-Fi Setup

• Initial Setup (Unconfigured): On first boot (or when credentials are not yet configured), the interactive CONFIG screen appears on the Apple II. Enter your Wi-Fi SSID and Password (press TAB to switch fields, and press RETURN to save). Settings are saved to on-board Flash.
• Subsequent Boots (Configured): Directly enters the connection screen and connects to the saved Wi-Fi network. Press the C key or ESC at any time while waiting for connection to open the CONFIG screen and modify settings.

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Building the Firmware

Builds are managed via the standard Raspberry Pi Pico SDK CMake workflow:

mkdir build && cd build
cmake -DPICO_BOARD=a2pico2litew ..
cmake --build .

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License

This project is licensed under the GNU General Public License v2.0.