[Gumstix-users] =?UTF-8?Q?Re:_[Gumstix-users]_Re:_[Gumstix-users]_Prop?= =?UTF-8?Q?osed_Robostix=E2=84=A2_Schematic_and_connector_layout?=

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

Hi Mark,

> > Why do you think that the serial port is so important? I'm just trying
> > to understand the issue.
> >
> Code reuse.
> 
> All the software I've used for my robot work has been serial port centric.
> 
> For instance consider boot loaders.  Most existing ones use the serial port.
> Without serial port communications between the atmel and pxa a new boot
> loader will need to be written.  (This may be a poor example, as a boot
> loader specific to this system would be needed)

With the setup Gordon is proposing, you don't need a bootloader, since
the gumstix will be able to program the AVR without a boot loader,
using the same technique that the AVRISP.

> Debug print's from the atmel side will be harder to implement, and will need
> to use non-standard libraries.  On both the PXA side as well as the atmel
> side.
> 
> I would like to re-use all the linux host based tools for atmel that are built
> around the assumption of the serial port being the communication to the
> atmel.

So, I agree with you a bit. But I also think it's a waste to tie up
two serial ports, one on the ATMega and one on the gumstix.

An option that I think would be good would be to take one of the
serial ports and level shift it to 5v and put it right next to the
ATMega one so that they could be jumpered together (to do wat you
want) or be used separately.

It also just occurred to me that with the proposed board, none of the
serial ports on the gumstix are available, since you can't use the
Robotstix alongside the Waysmall.

So, I now think that the extra voltage shifters should be used to
convert the Tx/Rx from one of the gumstix serial ports from 3.3 to 5v.
Then at least it could be connected to one on the ATMega.

I'd also like to see the other two serial ports brought out to headers
along with some more GPIO pins from the gumstix.

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