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Author Topic: Converting Wacom XD-1218-R from Serial to USB  (Read 3090 times)
kaiowas
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« on: February 02, 2013, 01:35:00 PM »

Doesn't look like anyone has done one of these before so I guess I get to start my own thread then...

I Recently acquired a brand new, boxed XD-1218-R as part of a clearout at work. It was fine for a couple of months until I upgraded the home PC to Windows 7 x64 then found out there was no driver support.  Angry

Whilst searching for driver solutions I discovered this place, read some threads and ordered a Teensy which arrived this week. Now it's time to start modding things...

I think I've got a handle on what I'm doing, I had the multimeter out this morning probing the board from the tablet, just want to make sure I've got all the steps down properly before I start cutting and soldering so here's the results of probing the board:


  DB9  | Internal | ADM202(RS/TTL)
-------+----------+----------------
2(RXD) |     8    | 14/11
3(TXD) |     7    | 13/12
4(DTR) |     3    | 8/9
6(DSR) |     4    | 7/10


Based on that and the other threads I think I'm doing the following:

Disable TA7805F by cutting the right hand leg (when viewed with the legs on the bottom edge)
Remove ADM202
Remove TR1R

Make the following connections:
Teensy VCC > Pad corresponding to the cut leg on TA7805F
Teensy GND > GND
Teensy D2 > Pad 11 on ADM202 (TTL side of RXD)
Teensy D3 > Pad 12 on ADM202 (TTL side of TXD)
Pad on the single pin side of TR1R > GND
Pin 9 on ADM202 (TTL Side of DTR) > GND

I'd like the installation to be neat so I'm planning on installing the Teensy inside the casing and would like to be able to unplug from either end. I think routing everything to a USB-B port into the casing would be a neat solution and allow the tablet to be connected via any USB A-B cable in future. I'm also considering routing all of the connections from the board to the Teensy via the existing internal connector as I think this will simplify any future dissasembly and reduce the risk of any wires getting pulled whilst the boards are out of the case. I'm undecided on the power switch. Easy option is to ignore it and accept it won't work, but I'm tempted to try running the 5v supply to the Teensy through it as a means of switching everything off (Depending on the type of USB-B port I manage to source this shouldn't be too difficult).
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bernard
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« Reply #1 on: February 02, 2013, 03:48:39 PM »

hello. I have such board here. I am on the go so without a picture it is hard to follow your mod. It seems you have a good understanding and you covered all the required signals. There is very little difference between the models.

for your usb B connector, I would pick the mini version (not micro) instead of the bulky B one. Cables are easy to find and the connector is quite sturdy while remaining low profile. Of course it might be more difficult to source case connectors.

power switch: go for the simple: no power switch. This is closer to how USB powered device work anyways. The tablet drops its power usage when no pen is detected you can measure the 5v current to see for yourself.

try to have the Teensy reset button accessible without opening the case. You'll thank yourself when you ever want to upgrade the Teensy firmware.
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kaiowas
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« Reply #2 on: February 03, 2013, 12:14:55 PM »

Apologies for the lack of pictures, I wasn't able to get any decent ones yesterday. I have added some below:

The whole board:


The area of interest:
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