Known Limitations and Roadmap

Known Limitations and Roadmap

General limitations

• Many newer backends have source-backed basic digital I/O but incomplete pull, alternate-function or hardware PWM validation.
• Direct register access depends on SoC register layout, page mapping and kernel/device permissions.
• GPIO expanders, EC/MCU/RT-core pins and isolated industrial IO may require libgpiod or a device-specific API instead of this mmap-oriented library.
• I2C/SPI metadata can differ by image and overlay. A compiled device path is not proof that the node exists on every distribution.
• Carrier/module confusion is a high-risk failure mode; an incorrect map can drive power, boot or board-owned signals.

Current roadmap

Newly implemented, hardware validation required

• BPI-SM10 / SpacemiT K3: detection, J12 map, K3 GPIO direction/read/write, pull and alternate-function register paths build locally; physical pin 18 is deliberately unavailable.
• BPI-CanMV-K230D Zero / Kendryte K230D: detection, JP1 map, two-bank direction/read/write and IOMUX pull paths build locally; physical pin 16 is deliberately unavailable.
• OpenWrt One / MediaTek MT7981B: exact detection, CN7 mikroBUS map and the board-specific 0x11d00000 GPIO-base selection build locally; pull, edge/PWM, bus nodes, permissions and real hardware remain unverified.
• K3 Pico-ITX / SpacemiT K3: exact detection and the eight application-CPU GPIOs on the 3.3 V 26-pin FPC build locally; RT24-owned pins and the complete 1.8 V 36-pin FPC remain unavailable by design. Pull/alt/edge/PWM, permissions and real hardware remain unverified.

Implemented but hardware validation required

BPI-F4 / Sunplus SP7350 has basic direction/read/write support and a terminal-row map. Pull, exact production detection identity, I2C/SPI device nodes and real hardware behavior remain unverified. SM10, K230D Zero, OpenWrt One and K3 Pico-ITX have stronger public source identity, but still require gpioinfo plus safe input/output tests on exact production images before their capability claims can be widened.

Needs exact internal board evidence

BPI-M2C, F2, F5, 2K0300, CM2+CM4IO, CM5+CM4IO, S64 Core kit and AI2H carrier.

Needs product scope decision

BPI-5202 module bus and BPI-2K3000 isolated IO.

R4 Mini and the standalone RK3588 Stamp-hole/Gold-finger core modules are now explicitly out-of-scope: the published products do not define a fixed raw user-GPIO connector for these Pi-style libraries. A separately named carrier with authoritative mapping can be evaluated as a future target.

Definition of done

A board is not complete until:

• exact board/carrier identity and authoritative mapping are recorded;
• detection and three numbering layers are consistent across both GPIO repositories;
• the code builds;
• safe hardware digital I/O passes on a named image;
• every untested pull/edge/PWM/bus function remains visibly limited;
• documentation and the support matrix are updated in the same change.