Scratch Sensor Board needs access to TTYUSB*

John Maloney jmaloney at
Thu Sep 11 17:50:05 EDT 2008

Hi, Jim.

Claudia Urrea would like to get the Scratch Sensor Board working on  
the XO. There was a minor bug in the Scratch serial port support,  
which I've now fixed. The fix will be in the next Scratch activity  
bundle. But the other problem is that the USB port is not readable and  
writable by default. I've posted some instructions at 
  (also attached below).

It would much better if XO users did not need to do this Unix black  
magic. Could we get this rule (or equivalent) into the standard build?


	-- John

NOTE: There is a bug in Scratch v7 and earlier that keeps the sensor  
board from working. I've fixed the bug and am working on updating the  
Scratch activity. But once the new activity is ready, the following  
should get the sensor board working.

To use the Scratch Sensor Board or Pico Sensor Board ( 
), you must add a file to the folder:


This file should contain the single line:

KERNEL=="ttyUSB*", MODE="0666"

Adding this file allows Scratch to read and write data to the sensor  
board. You will need to make yourself root using the "su" command in  
order to add a file to that folder.

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