From: Nate W <delaminator@gm...> - 2005-07-28 07:26:19
The robostix wiki page says that "If there is a gumstix on the header,
then one of the GPIO lines from the gumstix can assert the
level-shifter and connect the gumstix ttyS2 (ST-UART a.k.a. IrDA UART)
to the ATmega128's UART-0."
Does that mean that programming will eventually be possible without
the PXA<-->AVR serial jumper wires? Or should the wiki page say
something more like "...can assert the level-shifter *so that it is
possible to* connect ST-UART to UART-0"?
On 7/27/05, Dave Hylands <dhylands@...> wrote:
> I've added a new page on using the gumstix to program the robostix
> directly, no external ISP required:
> Dave Hylands
> Vancouver, BC, Canada
From: Dave Hylands <dhylands@gm...> - 2005-07-28 12:29:40
> The robostix wiki page says that "If there is a gumstix on the header,
> then one of the GPIO lines from the gumstix can assert the
> level-shifter and connect the gumstix ttyS2 (ST-UART a.k.a. IrDA UART)
> to the ATmega128's UART-0."
Hmmm. I think that there was a version of the schematic where that was
possible, but we talked Gordon out of it.
> Does that mean that programming will eventually be possible without
> the PXA<-->AVR serial jumper wires? Or should the wiki page say
> something more like "...can assert the level-shifter *so that it is
> possible to* connect ST-UART to UART-0"?
I think that the Wiki page needs to be updated. Here's how things look
from my perspective. Currently, there are two other methods by which
the gumstix and robostix are connected: 1 - SPI, 2 - i2c. In my mind
it seemed like a waste to permanently connect the gumstix and robostix
together by a third means, namely a pair of serial ports.
The ATMega's support a feature called self-programming, which makes
writing a bootloader possible. Currently, I typically use a serial
bootloader on all my ATMega's so I don't have keep connecting my ISP
programmer up. I'm envisioning both an SPI and I2C based bootloader
coming down the pipe. Then programming the robostix via ISP becomes a
one-shot deal, and using the jumpers isn't so bad.
Eventually, I expect that the robostix's will ship with a bootloader
already installed, but we're not quite there yet.
I also think that I (or somebody) can write a very lightweight ISP
programmer for the gumstix that only knows how to program using the HW
that the gumstix has. I expect that this will fall out of doing the
Eventually, I'd like to see having the two UARTs on the robostix
appear as additional tty devices on the gumstix side, and using them
will be the same as using the onboard ones.
It turns out that there are some nifty little surface mount devices
that could be used to programmatically connect the two UARTs together,
and Gordon may add these to a future design.
Hopefully some of my ramblings make sense.... :)
Vancouver, BC, Canada