Bruce,
Some revisions of the LH7A404-11 boards do not have caps on the touch signals. We are working on a new PCN about this, but it isn't ready for posting. I think you may find that this fixes the jittering on your touchscreen and you'll be able to calibrate much easier. You will find issues on the 6.4" kit and anything larger (10.4", 12.1", .etc).
Here is the info:
Quote:
On some earlier-but-recent part numbers, the boards did not have touch screen filtering capacitors in place. Two of our most recent distribution releases do contain the filtering capacitors (Product Change Notification document is en route). The card engine part numbers that do contain filtering capacitors are: 1001383 and 1001384. Boards without the filtering capacitors are 1001385, 1001048, 1001008, 1001133 and 1001009.
You can visually inspect the boards as well to determine the presence of the filtering caps: If you look at the card engine with the processor on top and the 144 pin SODIMM connector pointed towards you, the touch screen capacitors (or pads) are located on the left edge of the board, to the right of the test point bank from rows 3 to 6 (if row 1 is at the top containing T60 and row 2 is the next one down, etc...).
If your board does not have the filtering capacitors, any noise generated on the touch panel will have no hardware filtering to assist with jitter reduction.
Please advise on the state of your board. If your board does not have filtering capacitors installed, I would recommend you install them (they are 10,000pF ceramic capacitors). Any production systems you order will have these installed.
Thanks,
-Mike