This is not the droid you’re looking for. Because it’s not a droid – it’s a module.
Steve Drain has released version 0.20 of MCPIO, a small, specialised module to control the MCP23017 IIC expander ports on the Raspberry Pi, along with an updated version of Basalt with a new MCPIO keyword.
With an API that differs from the generalised GPIO module, Steve’s MCPIO module was originally intended to support the very cheap Ciseco SliceOfPI/O board, so it will also control the GPIO pins that this board brings to a single 8-pin header in the same way as the IIC ports.
The module is supplied within an application, !MCPIOMod [direct download], which includes the source code and manual. Also available for download is a test application, !MCPIOTest [direct download], which shows how the module can be used with Basalt. The test application includes both Basalt and the MCPIO module, along with their StrongHelp manuals.
A new version of Basalt (BASIC Alternative keywords), his module that adds many additional keywords and features to all versions of BBC BASIC V, the programming language that is supplied as standard in the ROM (or ROM image) of every version of RISC OS.
Version 1.60 [direct download] of the module, which Steve has labelled as a beta version, includes a new MCPIO keyword to control the IIC Expander ports on the Raspberry Pi, as well as a number of small bug fixes. The comprehensive StrongHelp manual [direct download] has been updated accordingly.
