wmb at laptop.org
Thu Dec 20 23:46:09 EST 2007
To add additional detail to the technique outlined below:
Here is a Digi-Key part number for an easy-to-use USB-to-serial chip:
Here is the datasheet for the part:
Use the schematic on page 26 of that document, except:
a) Connect VCCIO to 3V3OUT instead of to VCC (so the TXD output will be
the right voltage for the XO serial interface)
b) Leave RTS#, CTS#, CBUS0, and CBUS3 unconnected
c) Connect RXD and TXD to the serial connector that goes to the XO
Here is a part number for an adapter that will convert the surface mount
chip to a DIP pinout that is easier to work with:
Mitch Bradley wrote:
> As an alternative to wiring up a voltage converter chip, you can instead
> go directly to USB with a USB-to-serial chip such as a PL2303.
> The "traditional" arrangement is:
> USB-to-serial dongle -> DB9 -> serial cable -> DB9 ->
> But inside the USB-to-serial dongle there is:
> USB-to-serial-chip -> 3.3V-to-12V-voltage-translator
> So the chain:
> 3.3V-to-12V-voltage-translator -> DB9 -> serial cable -> DB9 ->
> is essentially a complicated hardware "no-op".
> There is little difference in the complexity of wiring up the
> USB-to-serial chip versus wiring up the voltage translator chip.
> John Watlington wrote:
>> No. You can use a standard USB/RS-232 serial converter, but
>> you will also need a voltage translator (such as a Maxim MAX3233 ---
>> you used to be able to get free samples from Maxim) and a male and
>> female connector to connect to the board. I'll dig up the connector
>> spec (Digikey carries them) and pinout and post them on the Wiki
>> soon. Remind me if you are in a rush.
>> The debug adapters cost us around $100 to make, due to the small
>> quantity built. We treasure them dearly, as we sometime need 50 or
>> more in a testbed!
>> On Dec 20, 2007, at 12:16 PM, Gerard J. Cerchio wrote:
>>> Hi All,
>>> Do the XO's ship with the serial/USB debug adapter?
>>> If not, how do I get one?
>>> Devel mailing list
>>> Devel at lists.laptop.org
>> Devel mailing list
>> Devel at lists.laptop.org
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