Re: Mindstorms USB connection and memory

In article <C351BAFF646DAC4F8F73F5F1AF064A0301BC298F@YS-EX-
CLUSTER.ysi.int>, Fred Mullins <[email protected]> writes
>
>If the slave is not connected to a master then it should be able to
>power-up the port and see if any slave is connected to it.

It is not safe to do this.  Perhaps there is a power-down PC connected,
that will be unable to deal with 5V being applied to the connection by
the slave.  For example the power may damage the USB port electronics,
(e.g. through reverse bias to the semiconductor), or the PC simply suck
too much power - which could flatten the battery of the portable device.

There are additional variations on these problems if a connection is
made whilst you are doing your probe for connected slaves.

USB On The Go gets around this by using new connectors:
http://www.usb.org/developers/onthego/OTG_Supplement_v1.2.pdf


A much more direct solution to the memory limit appears to be possible.
Remove the ARM processor, Atmel AT91SAM7S256.  Install a daughter
circuit board with processor with both more built-in memory (512 kBytes)
and extra pins for connecting external memory, Atmel AT91SAM7SE512.
This appears to be functionally an extended version of the current CPU,
that supports directly connected external memory such as a Compact Flash
card.

Of course you will need to find a workshop happy to do the substitution.
Hacking surface mount circuit boards is not something that I am happy to
do at home.

More info on Atmel's AT91SAM processor family here:
http://www.atmel.com/dyn/products/devices.asp?family_id=605#1724


Cheers,
Tony
-- 
  The NXT Step blog discusses the Lego Mindstorms NXT:
  http://thenxtstep.blogspot.com/