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Author Topic: Converting Wacom XD-0608-R from Serial to USB  (Read 21054 times)
bernard
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« on: March 27, 2011, 12:06:53 AM »

XD-0608-R (Intuos2 Serial 6x8)

There is a similar mod for the GD-0912-R here: (http://forum.bongofish.co.uk/index.php?topic=1927.0)

EDIT: This was the first mod I did and it might be a bit difficult to read. Since one person recently claimed to want to perform this on a XD-0608-R mod, I will re-write this post and also talk how to hook the teensy, etc.

Supply advertised as 9v-12v 0.1A  --

EDIT: With the mod described below, the board runs at 5v and pulls around 55mA when idle and ~60mA when sensing a pen. (This is with the 5v power regulator and serial driver disabled).

Warning: This mod will permanently disable the external serial & power connections. Playing with electronics is not without risks. You can break or burn anything including your fingers.  Smiley

The board was obviously built to be the same for USB and Serial. The biggest missing IC has the "USB" letters in it. As usual, the serial driver chip is present (ADM202) and there is what looks like a power regulator.

I am almost certain that I could connect my Teensy board in there (by removing or partially unconnecting the ADM202 chip) and (maybe) removing the voltage regulator as well. There are a lot of special Serial signals (CTS, DSR, DTR) (the same ones as we saw with Undersampled's TabletPC sensor).  I just hope these we can all connect either to ground or VCC only leaving TXD and RXD as active serial signals.


* XD-0608-R.jpg (261.39 KB. 1020x559 - viewed 953 times.)


Pinout from the ADM202 datasheet:


* adm202.png (66.05 KB. 912x571 - viewed 966 times.)


EDIT1: The serial markings are all "reversed" -- The names are the ones from the DTE side which was totaly confusing. I finally found the "real" serial pinouts and their usage by following the DB9 connector and the ADM202 pinouts to correlate to be sure. The markings didn't make sense since a pin like "DTR" is coming from the PC normally but according to the ADM202 pinout it was going the other direction!  

EDIT2: I was able to run the tablet only with a FT232R (TTL) sparkfun breakout board configured for 5V. The board provides both the 5V power and RXD/TXD lines. The 2 serial control signals (DTR & RTS) coming from the PC needs to be "grounded" (connected directly to ground) -- that is necessary else the board won't transmit coordinates. I was able to configure the Intuos2 and see the data on the virtual serial port.  This confirmed me that I will be able to substitute that with a Teensy in similar fashion as the tabletPC (but using a 5V supply -- no need for the 3.3v regulator).

Actually even if the DTR & RTS are high, the wacom will still allow transmition of config data like ~C<return> which outputs the max X and Y coordinates in plain ASCII.

The ADM202 can drive 4 serial signals. Two incoming and two outgoing. Well, there are 5 serial signals. So the fifth control signal is handled by analog parts (components in the corner near the connector, the main output being some sort of transistor - TR1R).  The ADM202 (and the analog for the fifth signal) has pullups on the TTL signals side. This is a bit of a problem and it took me a while to find that they need to be grounded.  So the course of action here is really the remove the ADM202 chip as well as the TR1R "transistor".

The regulator needs to be removed I think to avoid weird electrical states and 5V needs to be feed in place of one of its leg. One way to "avoid" removing it is to simply "cut" the leg, lift it and solder on the pad.

EDIT3: the board works initially at 9600 but then you can switch to 38400 with the "BA38<return>" command.  You then have to send a "ST<return>" so it starts sending coordinates. (All that info I have found in the linux driver). This is known as the Wacom Protocol 5 (V) it seems. I got +/-900 CPS (character per second) reading on my "realterm" software. For 9 character packets, that makes 100 samples per second.  

EDIT4: Here is a snap of the modified board:

* XD-0608-Rmod.jpg (264.98 KB. 1604x647 - viewed 1142 times.)


Explanation of the mod:
The numbers on the board : XD-0608  PWB-A483 - XABC GCMK-C2X
(The serial signal names below are from the DB9 connector not from the markings on the PCB).
The power regulator TA7805F has been "disabled" by cutting its leg on the red marking, this is where we inject the 5v input (red wire going to Teensy VCC). The wire is on the PCB pad, it is not touching the regulator leg. (difficult to see)
The ground can be connected in a lot of places, I picked the connector leg at 6 (black wire), but probably it would have worked on any of the ground "plane". (Connect to Teensy GND)
The ADM202 chip has been removed.
The TR1R transistor has been removed (serves the same purpose as the ADM202 chip).
The serial signals coming from the PC/Teensy other than TxD needs to be grounded:
  - A is RTS, connected to B and is connected to ground with the long yellow wire.
  - 1 is DTR, connected to ground at 2  
The serial signal (other than RXD) coming out of the intuos is left unconnected (the second ADM202 chip pad 5 is DSR).
The RXD signal is at 3 -- this is the main place where the intuos2 reports its coordinates. The most important signal! (Connect to Teensy D2)
The TXD signal is at 4 -- this is also quite important since I think the tablet won't talk without being told to. (Connect to Teensy D3)

« Last Edit: August 24, 2011, 06:57:09 AM by bernard » Logged
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« Reply #1 on: May 15, 2011, 12:52:42 AM »

Hey, bernard, just wanted to congrat you for all that work!!!!
Really, finding out how to power the board using 5V is great! I was thinking i'd have to look for this when i receive the UD-1218, as i dont like at all the idea of having a second power brick lying around .I want to try to make the UD-1218 use an usb interface (doing the protocol conversion, as discussed in other thread..), so it's great to know that it's indeed possible to power the board with the voltage provided by the usb connection!  Smiley
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bernard
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« Reply #2 on: August 23, 2011, 01:40:47 PM »

Get Waxbee version 0.9b or later.  Pick the "XD-0608-R to intuos2 6x8" template. Read the bundled readme html file for more info on how to program the teensy.
« Last Edit: August 24, 2011, 07:28:52 AM by bernard » Logged
xuz
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« Reply #3 on: August 23, 2011, 07:03:10 PM »

Thank you very much bernard.
I'll make the soldering done today, and as soon as teensy arrives, I'll let you know about how it goes.

D
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xuz
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« Reply #4 on: August 24, 2011, 01:42:53 AM »

Well I tried the first bit of soldering.
I marked the places where I have no wires attached to.

In your picture, are the wires to 1 and 2 bridged?

Where does the lead from the transistor going to?

Of course, since I don't have teensy yet, the wires are going to nowhere for now.



Thank you.
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bernard
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« Reply #5 on: August 24, 2011, 04:08:03 AM »

nice job!  I can see you played with this before:  clean pads after removal of the ADM202, tiny gauge wires, colored wire for the power, hotglue to hold the wires (mmm, I should do that too).

Watch out where you run the wires -- do not go too near the active area. I think it is fine where I see them now, but it is something to think about.

---

Yes, 1 and 2 should be bridged.  In essence we are grounding the pad. Since there is a ground via nearby, I connected it there.  I used a longer wire with the insulator remove in the first half. I soldered to the pad and to the via while holding the (long) wire -- I then cut the excess of wire.

---

The transistor is already hooked correctly with that magic jumper you installed near the PDIUSBD12 IC.  Try it with the multi-meter.   In essence, we just need to ground the signal that I referred as "A" in my picture.

---

I see 3 tiny wires hooked to the ADM202 pads, but really there should be two only (RX and TX), one of the signal must be left unconnected. It is the number 5 in my picture.

---

The power wire: We do not see very well and probably you did it right, but it costs nothing to ask: the regulator leg has been cut or lifted right? We do not want to connect to it. Also make sure the wire is never going to touch the 2 vias that are right below it: This is ground! ouch!
« Last Edit: August 24, 2011, 05:05:25 AM by bernard » Logged
xuz
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« Reply #6 on: August 24, 2011, 05:40:43 AM »

Thank you for your kind words.
I had a bit of practice on lifting SOIC's. I have a butane solder that can change to a heat gun when I change the tip.
About 10 to 15 sec under the heat gun and a tension at the side, the SOIC slides out beautifully.

Regarding shorts, I actually lost my fine solder bit and am working with 1/8 inch tip, so unintentional grounding is probably not out of question.
I've checked most connections with ground. 5V leg has been lifted.

Terimnals A, B, 1, 2 is grounded.
Terminal 5 to ground reads 36.6k ohms.
5V regulator pad to ground reads 3.8k. Hopefully I won't see smoke coming out.  Cool

By active areas, you mean on top of the areas that has the array of vertical and horizontal connections?
I will make sure that nothing goes over that. (Or maybe I'll do it later when everything is working just to see what happens.)
I was actually kind of surprised at how "little" there was in the ways of signal receivers.
At first I thought the pad was reading changes to wire's inductive characteristics as you pass the stylus over it,
but that can't be right. I'm pretty sure moving magnets over the pad doesn't disrupt that reading,
so the tablet must be doing something a lot smarter.  Huh

Again, thank you so much for the advices.
« Last Edit: August 24, 2011, 06:14:49 AM by xuz » Logged
bernard
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« Reply #7 on: August 24, 2011, 06:43:04 AM »

The active area is denoted with a white line rectangle, but the "antenna traces" reaches a little bit further (you can see them easily).  

Nothing connected I read:

36.4K for 5
2.4K for the regulator pad (my red power wire)
36.5k for 3
4.6M for 4

---

This is how I understand all this (so far):

There is a coil (with a core) in the pen -- but no magnet as far as I know.  This works like RFID tags.  The reader (e.g. tablet) emits strong electromagnetic energy that the coil in the pen picks up and powers itself.  The pen "resonates" (pen is tweaked to resonate to a precise frequency). The resonance emits back energy that is picked up by the tablet. (the tablet stops emiting energy and starts listening) -- this is happening quite fast.

The circuit quickly scans one "antenna" at a time (each vertical trace, then each horizontal trace).  The relative feedback "amplitude" of many antennas at the same time is used to compute a precise position. (2540 lines per inch reported precision!).  But that is not all. The coil is several mm above the pen tip so (I assume) the angle of the pen must be taken into consideration to make a more "precise" positioning of the "tip" touching the surface.  I assume the tiltx/y can be found by the "shape" of the area (a coil emiting energy will have a specific shape when transposed to the tablet).  In early Ultrapads (UD-* and also penenabled (TabletPC)) the buttons, the tip sensor and the eraser slightly modifies the R & C values connected to the coil R-C circuit and affect the resonant frequency (or something like that, I am guessing a little here). Smiley   In more recent tablets (GD,XD,...), it is a digital transmission over the carrier frequency (exactly like RFID stuff btw) which permits much more features, etc.

In some mouse and special pens, there is actually 2 coils at the tip next to each other -- that way the tablet can sense the "z-rotation" of the pen!  You can see some internal pictures in the Wacom Science thread.  
« Last Edit: August 24, 2011, 06:49:23 AM by bernard » Logged
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« Reply #8 on: August 24, 2011, 07:27:06 AM »

OK: the XD-0608-R basic pen support is now complete in waxbee version 0.9b -- the bundled template emulates a XD-0608-U and the menu strip fully works for this one! I just mapped the whole active area including the menu area: since it is the same tablet, it works magically.  Cool yay!

« Last Edit: August 24, 2011, 07:35:25 AM by bernard » Logged
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« Reply #9 on: August 24, 2011, 07:43:40 AM »

Two of the resistance readings are different.

>> 2.4K for the regulator pad (my red power wire)
3.8k (Gnd - red wire)
6.7k (Gnd - bent leg of the regulator)

Perhaps by coincidence, 1/(1/3.8 + 1/6.7) = 2.4k
Is there any chance that your multimeter lead might have contacted both your red wire and the bent up regulator leg when you measured?
If not, then I will need to look for the problem.


>> 4.6M for 4
For terminal 4, I'm getting around around 31 Mohms.
My gut feeling says that this difference is probably not a problem.

Otherwise, we are in agreement.


Thanks for the possible explanation behind the mechanism.
At my work, we have a 3 dimensional digitizer called Polhemus Fastrak.
It uses similar idea as well. 3 transmitters at unique RF that is picked up by the stylus.



Edit: I just read the new post about waxbee.
The software engineering part of the project is without a doubt, invaluable.
Thank you very much.
« Last Edit: August 24, 2011, 07:46:49 AM by xuz » Logged
bernard
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« Reply #10 on: August 24, 2011, 02:39:32 PM »

I think the readings are fine but double checking is not going to hurt. No, I was not touching the regulator leg and I tried 3 times, I also tried from the tip of my red wire.  Reading Ohms differences through a complex circuit is not the most reliable thing IMHO -- this board has a lot of stuff.  I think the numbers are close enough.  If you (happen) to have a lab power supply (with current limiting) that would be the first thing to try (but I doubt you have such equipment Smiley ).

It will be fine Smiley     For safety I would proceed this way, when you get the Teensy. Solder the GND and try the 5V just by touching leads for an instant. Check the temperature of ICs on the board. Try longer times until you feel nothing is burning. Also monitor the tablet LED -- it should lit. Then try powering and playing with the pen: the tablet led should blink as you touch the tablet.   When all that works fine, solder the 5V and then solder the TX/RX signals.

« Last Edit: August 24, 2011, 02:41:35 PM by bernard » Logged
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« Reply #11 on: August 27, 2011, 05:02:56 AM »

Good News bernard,

My Teensy is here, and after some tinkering, my tablet is working again!!!!!!!!!
That felt good.

A few things.

1) I could not use your waxbee.jar on my Win 7 64bit with sun java 1.6.
What I did instead was to use your program to make a hex file.
I then used the teensy loader to load the hex file into teensy, and everything worked right away.

2) Everything seems to work fine. Wacom's tablet configuration tool works.
I set the tablet to use only my right monitor with portioning to make the aspect ratio correct.

3) It does not work in Photoshop and Illustrator CS5. (Works fine in MS Paint.)
When i move the cursor over the Adobe areas, the cursor just seizes up.
I can make it jump from one place to another within the Adobe windows area by lifting the stylus
completely off of the tablet, moving it to another location, then lowering it to the tablet. This makes it jump from one point to another.
What I can't do is to drag the cursor over the windows area normally.
Did you have any experiences similar to this with Adobe products?

Unplugging and replugging the usb cable removed the Adobe only problem. I suppose reboot would have fixed the problem as well.
So everything is working perfectly, including pressure sensitivity.


I can't thank you enough for helping me through this. Much thanks, bernard.

D.



**********************
P.S. I decided to keep the tablet's serial cable intact. The Teensy device is glued to the serial plug. Not the prettiest but it works well and it's very sturdy.


* CRW_6895.jpg (96.32 KB, 600x400 - viewed 728 times.)

* CRW_6896.jpg (108.33 KB, 600x400 - viewed 773 times.)
« Last Edit: August 27, 2011, 05:14:23 AM by xuz » Logged
bernard
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« Reply #12 on: August 27, 2011, 05:40:28 AM »

Very happy that it works for you!  Your tablet will now work virtually everywhere and painlessly (provided you install the latest wacom drivers of course).

You need to run it with java 1.6 (sun) but: the 64 bit version of the JRE (to get the programming part to work) -- the 32 bit version will barf with an error like open(z) or something like that. I am not done re-compiling the .dll in 32 bit mode.

EDIT: Windows/JRE 32 bit now works with version 0.10 and up.

Anyway, I did the .hex generating as the workaround and it works nicely too. Just a few extra steps, no big deal.

The Adobe thingy -- this has nothing to do with the teensy (I think), it sounds like a Wacom driver issue to me. If you see other quirks, even if you do not really care about it, please report it anyway.

So how did you connect the stuff inside the tablet? This is clever stuff!

you could have picked the other GND and VCC holes -- they are closer to the reset button.
« Last Edit: September 06, 2011, 06:33:50 AM by bernard » Logged
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« Reply #13 on: August 27, 2011, 10:11:28 PM »

>>  the 32 bit version will barf with an error like open(z) or something like that.
This was the exact error, I will have to download the 64 bit version java.

>> So how did you connect the stuff inside the tablet?
I simply removed the female connector from the internal end of the serial cable.
I used multimeter to find which connects go to which, and soldered the 5V/Gnd/RXD/TXD to those 4 wires.
From the external end of the cable, I used a few jumper wires with small bead of solder beads at the end to tap the 4 wires.
These wires are soldered to Teensy.
See the attached pics for internal.

>>you could have picked the other GND and VCC holes
I hadn't noticed the other VCC/GND. If I ever reuse the teensy, I would consider that option for sure.

>>it sounds like a Wacom driver issue to me
This may be the case, I'm using a slightly older version of wacom driver (605-7).
I'll have to try the newer version of wacom drivers.
The Adobe experience is mixed.

1) When adobe programs are running horizontal usable area becomes smaller. It almost seems like Wacom or Adobe is switching the usable area when Adobe is running.

One possibility is that I have 2 monitors. One is 1280x1024 (monitor 2) and other is 1920x1080 (monitor 1). I have the pen to only use the monitor 1. When Adobe program is active, then the horizontal usable area is only about 1280. I will need to tinker with this a bit more. (Reinstall windows/wacom/photoshop/etc.) I'll let you and the community know.

Uninstalling the older driver and installing the newest driver solved the issue. No more issues with photoshop and illustrator with usable area repositioning.

2) As you can see from the last pic, the pressure sensitivity on photoshop changes randomly. I tried to just make small vertical strokes with equal strength. Every once in a while, randomly, the sensitivity jumps to maximum, then returns to normal. I am not sure what is causing this. i will need to install latest wacom drivers first to see if that solves the problem.

 

* CRW_6898.jpg (74.32 KB. 533x800 - viewed 627 times.)


* CRW_6897.jpg (123.44 KB, 800x533 - viewed 847 times.)

* strokes.jpg (51.5 KB, 500x500 - viewed 664 times.)
« Last Edit: August 27, 2011, 10:39:21 PM by xuz » Logged
bernard
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« Reply #14 on: August 27, 2011, 11:06:33 PM »

Cut and resoldered the other end of the cable, then I am a bit puzzled as to why you kept the 9 pin bulky connector? I assume this was just so it is faster to build? (no need to skin more wires??)  Anyways. if it works, it's fine. Smiley

Pressure sensitivity:  First time I ever see/hear about this.

First: Is this only happening with Adobe Photoshop?   Did you know that you could setup different Wacom profiles for different applications -- in the Wacom control panel you can have separate settings for adobe photoshop for example -- (that would explain your initial area issue).  So first make sure the wacom control panel is all good -- there is actually a button to "reset to defaults" I believe.  Try that. and remove any configuration related to other software (if any).

If you think there is something weird happening with the tablet, I have quite a few tools to trace exactly what is happening from the tablet serial communication up to the USB packets. I can even record events and play them back here on my own machine Smiley  So if you are willing to give it a try, it might help pinpoint the "cause" of the issue.
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