[Gumstix-users] Problems using I2C on Overo & Tobi board

[Markus S. <msv...@ae...>]

Dear gumstix-users,

I'm having some trouble getting started using I2C communication. My end 
goal is to be able to communicate with an LCD2041 LCD display from 
Matrix Orbital 
(http://www.matrixorbital.com/p101/LCD2041-WB/product_info.html).

On the Overo, I logged in and used the i2cset program (from i2c-tools 
package), to try to send some commands to the LCD. When I connected a 
scope between the Gumstix GND and GPIO184_SCL3 (pin 23 on the Tobi) I 
didn't see any activity. I expected to see some clock pulses. Also, the 
following error message appeared:

i2c_omap o2c_omap.3: timeout waiting for bus ready
Error: Write failed

This is the i2cset command line I used:

i2cset 3 -y 3 80 88

(The value "80" is the default write address of the LCD2041. The value 
"88" is supposed to clear the screen.)

There is a Sparkfun logic level converter between the Overo and LCD2041 
I2C pins, to go from 1.8V to 5V. I read through the available Gumstix 
I2C documentation, and I think I am doing everything correctly... Has 
anyone had similar problems? Does anyone know what the solution is?

Many thanks,
Markus.