Re: [Gumstix-users] i2c 'robostix address' rb 'regadd 'returns 'regadd'

[Dave H. <dhy...@gm...>]

Hi,

On Thu, Oct 28, 2010 at 10:43 PM, VaibhavGhadiok
<vai...@gm...> wrote:
>
> Hi Dave,
>
> I tapped into the 3.3V SCL/SDA lines on the robostix and hooked those lines
> directly up to the sensor, but still no change in what happens. Haven't
> tried the logic analyzer yet, but from the oscilloscope, the SDA commands
> are correct. Sequence is on SDA: start high, then 0 for start, then 1101001
> (0x69 address), then 0 (read), 1 (no ack) then 0, then back to high. I ran a
> shell script with the command "i2c 0x69 rb 0x00" to run multiple times and
> also to check multiple addresses. The SDA output is the same on the 5V
> robostix side as well as if I do go through the 3.3v logic converter, so it
> seems like there isn't any difference. I've attached pictures of the oscope
> output for the 5V (pic 905), 3.3v using logic converted (pic 906), 3.3v
> gumstix direct (pic 907).
>
> Also - made a mistake on the robostix pullups, they are 2Kohm, not 10Mohm.
> Removed them (robostix apparently has 10K pullups) but this didn't change
> anything - there are 10K pullups on the sensor.
>
> Seems like the sensor is just not responding - unlikely it came dead on
> arrival, but can't think of anything else. Anything we can try to test it
> out?

I'm assuming that you connected GND from the sensor to GND on the robostix?
And you connected VLOGIC to VDD?

You could try all 126 addresses (from 1 to 127) to see if anything responds.

It's hard to tell if that trailing zero is an ACK or not without
seeing the SCL signal that goes with the SDA signal. The device is
allowed to stretch the clock, so you really can't assume where the
clock edges are.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.DaveHylands.com/