[Sugar-devel] USB permissions for educational robots

Paul Fox pgf at laptop.org
Tue Jan 3 09:12:02 EST 2012

roughly speaking, we chose the "dialout" group because a) it's a
traditional group for access to UNIX serial devices, b) many USB
devices that activities need access to are actually serial devices,
and c) the "olpc" user is already a member of "dialout".  is it
important that Lego devices be protected by a separate group

the current udev rule isn't added by Sugar -- it's in the olpc-utils
rpm distributed by OLPC.  we can add a modified rule once we agree
on what it should look like.

i can't remember at the moment where the default passwd and group
files come from -- if the rule needs a new group, we'll need to modify
those files as well.


alan jhonn aguiar schwyn wrote:
 > Hi,
 > In a few of months, all our High Schools (of Uruguay) will receive and robotic 
 > kit (Lego).
 > At "Universidad de la República", "Facultad de Ingeniería" we are workingwith 
 > it and the XO...
 > http://www.youtube.com/watch?v=S8HRbDLO7LM
 > In other parallel road, we are working on a 2.0 version of the Butia Robot
 > www.fing.edu.uy/inco/proyectos/butia
 > That uses USB4all IO board  which resulted from a thesis given at ourUniversity 
 > (also will have arduino compatibility)
 > http://www.fing.edu.uy/inco/grupos/mina/pGrado/pgusb/
 > USB4all is based on 18f4550 pic.The vendor is Microchip, 
 > SYSFS{idVendor}=="04d8"And have: productID=0x000b //bootloader          
 > productID=0x000c //pic18f4550 generic comunication
 > The actual Sugar image, only have permissions for LEGO WeDo.
 > If you see in: /etc/udev/rules.d you find the correspondient: 
 > "30-olpc-wedo.rules".
 > The file add this rule:
 > SYSFS{idVendor}=="0694", SYSFS{idProduct}=="0003", GROUP="dialout", MODE="0660"
 > This means: 0694 is LEGO                   0003 the model: WeDo
 > To the NXT we need add: {idProduct}=="0002"
 > But, for each model add a new line.. not is a good form..
 > Exist another way, a generic rule:
 > BUS=="usb", SYSFS{idVendor}=="0694", GROUP="lego", MODE="0660" 
 > That says: if is USB and fabricated by 0694 (LEGO) lets 0660 (4: read+ 2: write)
 > If add this permissions to "lego" group, we need create it..
 > But, we don't make it, an use an existing group like "root"? Or another... 
 > Suggestions?
 > We can make a generic group "robot" that have permissions for: lego wedo, lego 
 > nxt, butia, etc...
 > Regards!
 > Alan 		 	   		  part 2     text/plain                 129
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 paul fox, pgf at laptop.org

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