Compatibility of serial adapters

2015-10-21 Thread Peter Easthope 
Seems that an adapter such as http://www.ebay.ca/itm/381346598663 ,
similar to the first generation adapter, might work.  The concluding
sentence in
http://wiki.laptop.org/go/Serial_adapters#First_generation_serial_adapter
is "This only works on the XO-1."  What prevents it from working on an
XO-1.5?  Can anyone elaborate on this compatibility topic?

Thanks,   ... Peter E.

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Re: Compatibility of serial adapters

2015-10-21 Thread Paul Fox 
peter wrote:
 > Seems that an adapter such as http://www.ebay.ca/itm/381346598663 ,
 > similar to the first generation adapter, might work.  The concluding
 > sentence in
 > http://wiki.laptop.org/go/Serial_adapters#First_generation_serial_adapter
 > is "This only works on the XO-1."  What prevents it from working on an
 > XO-1.5?  Can anyone elaborate on this compatibility topic?

i believe it's because the later adapters are USB adapters, and are
powered from the USB side.  the old XO-1 adapter gets power from
the laptop -- that power isn't available from later models.  (read
the descriptions of "Pin 1" in the Electrical Details section of
the page you linked to.

paul
=-
 paul fox, p...@laptop.org
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Re: Compatibility of serial adapters

2015-10-21 Thread Peter Easthope 
On Wed, October 21, 2015 12:22 pm, Paul Fox wrote:
> i believe it's because the later adapters are USB adapters, and are
> powered from the USB side.  the old XO-1 adapter gets power from the
> laptop -- that power isn't available from later models.  (read the
> descriptions of "Pin 1" in the Electrical Details section of the page you
> linked to.

Yes, I noticed that pin 1 doesn't supply power on the 1.5.
Power needn't come through the serial connector.  Tapping
elsewhere should be possible.

Thanks,   ... Peter E.

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Re: Compatibility of serial adapters

2015-10-21 Thread James Cameron 
On Wed, Oct 21, 2015 at 11:38:02AM -0500, Peter Easthope wrote:
> Seems that an adapter such as http://www.ebay.ca/itm/381346598663 ,
> similar to the first generation adapter, might work.  [...]

Doubt it.  The product description is inadequate, it does not state
the serial voltage.  It does say supply voltage range.  It does not
have any serial control signal strapping.  And it has an RS232
connector, which nobody should need these days.  ;-}

Get a USB adapter instead.  As long as the adapter is for 3.3V serial,
it will work with the XO-1 host serial port.  The adapter is powered
from the USB host.

The same seller has a more appropriate adapter for a lower price:

http://www.ebay.com/itm/USB-TTL-Converter-Module-LED-CP2102-RX-TX-3-3V-5V-Output-/381153344387?hash=item58be827b83

There are now very many alternative adapters that are compatible.

-- 
James Cameron
http://quozl.linux.org.au/
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Re: Compatibility of serial adapters

2015-10-21 Thread Samuel Greenfeld 
If I recall correctly, the XO-1.5's serial adapter shares some circuitry
with the camera.  Booting an XO-1.5 with a serial adapter means you cannot
use the latter.

To do this, the XO-1.5 looks for a resistor placed across two of the wires
to see if a serial adapter is present.  No other XO laptop model has this
restriction.

Perhaps the older serial adapter simply lacks the sense resistor required
for the XO-1.5 to switch modes.



On Wed, Oct 21, 2015 at 5:15 PM, James Cameron  wrote:

> On Wed, Oct 21, 2015 at 11:38:02AM -0500, Peter Easthope wrote:
> > Seems that an adapter such as http://www.ebay.ca/itm/381346598663 ,
> > similar to the first generation adapter, might work.  [...]
>
> Doubt it.  The product description is inadequate, it does not state
> the serial voltage.  It does say supply voltage range.  It does not
> have any serial control signal strapping.  And it has an RS232
> connector, which nobody should need these days.  ;-}
>
> Get a USB adapter instead.  As long as the adapter is for 3.3V serial,
> it will work with the XO-1 host serial port.  The adapter is powered
> from the USB host.
>
> The same seller has a more appropriate adapter for a lower price:
>
>
> http://www.ebay.com/itm/USB-TTL-Converter-Module-LED-CP2102-RX-TX-3-3V-5V-Output-/381153344387?hash=item58be827b83
>
> There are now very many alternative adapters that are compatible.
>
> --
> James Cameron
> http://quozl.linux.org.au/
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