I am not using the Robostix with a gumstix.  I’m simply trying to communicate with a Devantech SRF10 ultrasonic sensor over i2c, but I seem to be having problems.  I’m not exactly sure if my problem is in hardware or in software.


The Robostix board has built-in pull-up resistors for the SDA and SCL lines, right?  So I haven’t added any external pull-up resistors.  I’m sending the ultrasonic a command to start ranging (or pinging), and I can actually hear the sensor firing.  However, when I try to read from the sensor, I’m always receiving a high signal.  I’m trying to read two bytes, so I’m receiving 0xFFFF.


Does anyone have any suggestions as to what I’m doing wrong?  Is there anything else in hardware that I need to be doing?