Re: GPIO endianness on MPC8349

[Ben Warren <bwarren@qstreams.com>]

[-- Attachment #1: Type: text/plain, Size: 1389 bytes --]

Sorry for wasting bandwidth (again).  Turns out my schematic is for an
earlier spin of the board.

regards,
Ben

On Mon, 2006-04-10 at 15:06 -0500, Kumar Gala wrote:

> On Apr 10, 2006, at 2:48 PM, Ben Warren wrote:
> 
> > Hello,
> >
> > I'm a noobie to this CPU, and am utterly confused with how the bits  
> > are
> > ordered on the GPIO ports.  I imagine it's the same as all Freescale
> > PPCs, but who knows.  Anyway...
> >
> > Using an MPC8349MDS eval board, I have one LED to play with.  From the
> > schematic, it's connected to GPIO1[1].  From other processors that  
> > I've
> > worked with, I would have expected to toggle it with either 0x40000000
> > (IBM 405) or 0x00000002 (68360).  Nope.  To make this bit move, I mess
> > with bit 0x00000040 in the appropriate DAT register.  This leads me to
> > believe that either the bit ordering is something
> > like ...89abcdef01234567 (sorry for the confusing notation, but
> > hopefully it makes sense) or the schematic has a typo.  Since I'm  
> > trying
> > to write a generic GPIO handler, I'd like to have a little  
> > confidence in
> > my extrapolation from a single point.
> >
> > Can anybody shed some light on this?
> 
> This is because the Freescale docs are misleading.  If you look at  
> the schematic you will see the LED is wired to GPIO1[5] which makes  
> sense for the 0x40 value you have to use.
> 
> - kumar

[-- Attachment #2: Type: text/html, Size: 2480 bytes --]