I am also interested in FFI for the Pi. Specifically I'm interested in using the Pi's I2C capability. I noticed that my raspbian distro has so.SqueakFFIPrims installed along with other plugins in /usr/lib/squeak/4.10.2-2793. Does this imply that the necessary support is in place?
Note though I loaded Squeak4.4-12327 onto the Pi and installed FFI, but none of the FFI tests pass. The failures are "Unable to find function address" Errors. "Smalltalk current listLoadedModules" lists SqueakFFIPrims as a loaded external plugin after attempting to run the tests. I can't tell if there is missing functionality in the FFI support or if I got things misconfigured somehow.
The Scratch/python interaction is quite slick. I tried it out and got Scratch to turn some LEDs on and off. In the spirit of PhysicalEtoys, but for Scratch on the Pi, there's also similar Scratch to python connections used here: http://www.pridopia.co.uk/rs-pi-set-scratch.html. In addition to GPIO examples, they also have I2C and SPI examples. As Tim says, it would be good to have a more direct interface.
Doug
On Dec 26, 2013, at 10:54 , tim Rowledge wrote:
On 26-12-2013, at 7:11 AM, marcelo Cortez jmdc_marcelo@yahoo.com.ar wrote:
hi
I'm developing over Raspberry pi with squeak and i need access to GPIO.
Questions:
How load FFI on Raspberry pi? Any link,paper , advice , pdf. be appreciated.
To get the FFI working for Pi (and indeed other ARM *nix machines) somebody would need to write any needed ARM assembler bits to interface to the apicall and/or libffi and/or whatever the current facility is called. There is some information on what is needed in the vm sources; see http://squeakvm.org/cgi-bin/viewvc.cgi/squeak/trunk/platforms/unix/plugins/S... and start with 00README. Probably the best place to ask more specific questions about FFI would be the squeak vm-dev list (sign up at http://lists.squeakfoundation.org/mailman/listinfo/vm-dev)
It’s definitely a job I have on my list of TO DO, but not high and there’s plenty of work piled up above it so please feel free to tackle it!
It *might* be easier in the short term to write a vm plugin specifically for the Pi GPIO interface. You can find out quite a bit about the gpio programming fro mthe Pi forums and particularly from the Scratch forum where simplesi has done a great deal of clever stuff by using python to provide a connection for the Scratch remote sensor connection subsystem, and then driving the gpio from pythin. It’s certainly time there was as more direct interface for him to use.
tim
tim Rowledge; tim@rowledge.org; http://www.rowledge.org/tim Strange OpCodes: SBB: Store in Bit Bucket