K2 Serial port connection

The K2 is just a small screen DX(G) - so I can confirm that the serial port connections are the same:
See pic #1 on:
http://www.mobileread.com/forums/sho...55&postcount=1

Those four pads are numbered:
1 - reference <- -> (optional, if required by adapter)
2 - Tx (from K2) <- -> adapter Rx
3 - Rx (to K2) <- -> adapter Tx
4 - Gnd <- -> adapter Gnd

The reference (and idle Tx) measure 2.7 volts - -
So a 3.3 volt, lv, ttl to usb converter should work.
And of course, any adapter that accepts an external reference (the jim.sh ftx board).

Note: You open a K2 the same as the DX(G) also.
The little tabs you have to push down are located 1-3/4 inch in from each side.

Edit:
The output levels are too high for 2.5v cmos convertor, so a 3.3v should work.
See attachments.

The jim.sh/ftx adapter can be set at a fixed 3V3 or to use an external reference.

I decided to go with using the external reference.
Even though it sometimes means a bit of a hassle to get it working -
I.E: The interface reference voltage (the Kindle) has to be 'on' at or before the USB connection is made.

If I had gone with the fixed 3v3 setting - then the interface level would have been generated from the USB bus power.
Ah, but the I/O levels would only be an approximation of what Lab126 set this thing up to use.

So far, using it in 'external reference' mode - I am getting good, solid, noise free serial communications with the device.

Attached Thumbnails