Re: [Gumstix-users] gpio 66 special?

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

Hi DJ,

> I'm debugging my furnace board, and board #2 has the same problem as
> board #1 - zone 3's controller is unreliable.  I've traced it to the
> reset line from the gumstix to zone3's MCU, which is GPIO66.  I use
> GPIO's 64, 65, 66, and 67 to reset the MCUs (part of the ICP logic).
> GPIOs 64, 65, and 67 are fine - they're solid high.  GPIO 66 seems to
> be toggling when I do i2c operations.  I can monitor it via
> /proc/gpio/GPIO66 and indeed, it's set to "out" and it's toggling.
> When I stop using i2c, it stays at whatever state it was at.
>
> Note: I'm not even i2c'ing to that zone!  I'm talking to one of the
> other zones, and this one is the one that always gets reset.
>
> Any ideas?  Is this some left-over debug thing in the i2c driver?

I don't recall seeing anything like that.

Here's a test you can try to see if its a hardware issue.

Don't load the i2c modules and run the i2c-test program. This will
print out the gumstix's view of the i2c pins.

Then manually toggle GPIO 66 and see if either the SDA or SCL values
change. If it does change, then there is some type of hardware
coupling between GPIO66 and one of the i2c lines.

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