maybe you need to load the i2c modules...
see this page: http://docwiki.gumstix.org/I2C_on_the_Gumstix#Starting_i2c


On 12/4/06, Ian Smith <itsmith@cs.wmich.edu> wrote:
Jesse Welling wrote:
> I'm guessing you need some signal shifting then...
> you also need a pullup on the scl line as well....
>
> about the address: it depends largely on what pins are pulled high or low
> on the max128. if you leave them floating i think you will get fairly
> unreliable output...
> but you want to use the non shifted address. for some reason I
> miscalculated the binary
> value. the range is 0x28 to 0x2f so if you arn't using a number in
> there you arn't using a max128.
>
> On 12/4/06, *Ian Smith* <itsmith@cs.wmich.edu
> <mailto:itsmith@cs.wmich.edu >> wrote:
>
>     Jesse Welling wrote:
>     > If I've been doing things right with my robostix (and it's been
>     > working so far)
>     > the i2c program takes the rb with a comand byte to be two operations
>     > on the i2c bus
>     > first a write of the command byte, and then a read opperation. I
>     was
>     > inittialy worried about this, but
>     > it seems to be working out ok.
>     >
>     > So let's say you want to read channel 0 with full scale and no
>     sleep of a
>     > max 128 at address 0101000 (all address lines held low)
>     >
>     > this is the command:
>     > i2c 0x50 rb2 0x88
>     >
>     > and out should pop your value but beware that this is probably byte
>     > stream order (e.g. low byet first then high byte)
>     >
>     > Hope this helps....
>     >
>     > On 12/4/06, * Dave Hylands* <dhylands@gmail.com
>     <mailto: dhylands@gmail.com>
>     > <mailto:dhylands@gmail.com <mailto:dhylands@gmail.com>>> wrote:
>     >
>     >     Hi Ian,
>     >
>     >     > it may just be getting late and im confused, but can i
>     used the i2c
>     >     > program that allows read and write byte? the writebyte command
>     >     wants a
>     >     > slave address register and data, but i cant seem to figure
>     out what
>     >     > register to send to?
>     >
>     >     Most i2c devices have a notion of a register number. For
>     these types
>     >     of device, the first data bybte is the register number. It
>     appears
>     >     that the max128 only has a single register, and the first
>     byte is the
>     >     control byte.
>     >
>     >     I haven't played with the Max128 before, so I'm not sure if an
>     >     ordinary read cycle where the control byte is passed as the
>     address
>     >     will work or not.
>     >
>     >     The i2c program doesn't currently have a mode to perform a read
>     >     without writing a command byte, but I could add one, if
>     required.
>     >
>     >     --
>     >     Dave Hylands
>     >     Vancouver, BC, Canada
>     >     http://www.DaveHylands.com/
>     >
>     >
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>     hey, i tried your method, and no luck, could it be because i am on a
>     breakout-gs? ive added my own resistor on the sda line so that should
>     take care of the lack of pullup resistor.  also should it be 0x50,
>     or 0x40?
>     -Ian
>
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ive put a 10k resistor on sda and scl, while issuing ./i2c 0x28 rb2 0x88
and i keep getting a remote IO error from ioctl

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