Accessing Beagle XM I/O expansion pins from Basic

Oops, yes, thinking millionth of a second and wrote millisecond.

I’ve updated the GPIO module so that all machine types have their own lookup table, so it will be easier to add new machine types to the module….
Usual Download

Tank: why aren’t all of the expansion port’s pins accessible via the 32-bit-wide SWIs? e.g. GPIO 141.

Tank: why aren’t all of the expansion port’s pins accessible via the 32-bit-wide SWIs? e.g. GPIO 141.

GPIO 141 is not part of the expansion header (see table 22 page 107 of the SRM)
If you are thinking of 161, then that is outside of the 32 bits that cover the most pins on the header, so anything below GPIO 128 and above GPIO 160 will not be accessed. There is a bitmask in the source for each header that will be returned to the caller when one of the 32bit SWI’s are used. See this for a bit more info.

GPIO 141 is not part of the expansion header

Ah… that’ll teach me to read the schematics more carefully in future.

Perhaps.

If it helps anyone else, there was a reminder on the BeagleBoard mailing list recently that there is a separate copy of the schematics of every version of every BB on the BB web site. The separate schematics are of high quality, whereas those in the SRM are pixellated to the point of illegibility. A case of Microsoft being as helpful as usual.

Please see Here for a new version of the GPIO module.
This changes the way the Raspberry Pi sets the GPIO_WriteOE and how the value is returned from GPIO_ReadOE, to match the Beagle and DevKit.
It also adds I2C driving for the MCP23017 GPIO expander chip (16-bit IO). Just the basic OE and output/input reading/writing are supported at present.

Just wondering if Benchmarking Raspberry Pi GPIO Speed is of any interest here.

New version of the GPIO module and the config app.
Lots of bug fixes for the Raspberry pi side of things.
The config app now works on the Pi as well. (Hopefully on rev2 boards as well).
It also controls any MCP23017 extenders attached to the I2C bus. It is limited to extenders that are addressed sequentially, but can start at any selectable address. (press adjust to open a second window. it will only open if any extenders are fitted).

A quick update to the GPIO module that fixes a bug when used on a revision 2 Raspberry Pi.

“Just wondering if Benchmarking Raspberry Pi GPIO Speed is of any interest here.”

Crikey, Python is slow isn’t it? I’ll have to dust off my old BASIC V BB-XM GPIO prog and see how it does on the R-Pi under RISC OS.