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Author Topic: Help identifying pinout on tablet pc digitizer  (Read 69758 times)
bernard
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« Reply #15 on: November 18, 2010, 01:51:13 PM »

Mine is 10 pins -- and yours is 14 pins -- that's 4 pins difference -- exactly the USB.  So if really, they just added 4 pins for usb, then, the usb could be located at pin 11,12,13 & 14.  (you can see the pin numbers 1 and 14 on your PCB picture).  Does that match the cable when plugged in?

First identify the ground signal -- it is typically the one that has the most coverage on the PCB and is often connected to screws and whatnot.  Next in list is to find the power. One way to find the power is to find the datasheet of the components on the board -- namely the standard ICs (Integrated circuits) -- Here it seems that we have two standard ICs and one custom IC (Wacom).  They are marked "IC".  Can you read the small numbers on the IC2 ?  (the one that has 3 pins) I see "LC" but not sure.

IC1 number looks like a Microchip "clone".  87F16C8A  -- the "F16C8A" looks microchip to me. EDIT: I did not find that part or an equivalent -- it kinda feel like the microchip numbering but it isn't.
« Last Edit: November 18, 2010, 03:57:57 PM by bernard » Logged
bernard
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« Reply #16 on: November 18, 2010, 07:34:28 PM »

That is a wild guess but it is very possible that the two USB data lines (D+ and D-) might have a 22 or 24 ohm resistor in series before going to one of the IC pin. This seems to be a typical arrangement for USB devices. (but again, this is a very wild guess).

USB D+ pin --- 22 ohm ---- IC
USB D- pin --- 22 ohm ---- IC

« Last Edit: November 18, 2010, 07:42:53 PM by bernard » Logged
UnderSampled
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« Reply #17 on: November 20, 2010, 01:17:06 AM »

Hello,
Here is the final result of what I got when I when I was working on this:

Pin No.Signal Name (Probable Meaning)I/O
1Ground-
2??????
3??????
4??????
5??????
6??????
7Data Terminal Ready (DTR)O
8Request to Send (RTS)O
9Received Data (RxD)I
10Transmited Data (TxD)O
11(GRD) (Unknown Signal)I
12DBGEN-P3N + PLTRS1-E3N (Unknown Signal)O
133.3v Power-
14Ground (GND)-

It'd be really cool if the tablet already outputs USB. Then we wouldn't have any driver issues.
Regardless, these should work if you can connect to them. Note that you only really need pins 9, 10, 13, and 14. Of course it's better if you have the others.
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bernard
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« Reply #18 on: November 20, 2010, 03:23:01 AM »

Thanks for jumping in Undersampled! 

ah yes, I remember those names -- and some of my (unproven) theory was that:
- the pin 12 could be for "enabling" the device 
- the GRD is for driving a "dual" led -- but that was totally unproven.

Looking at your cable colors:
- The two grounds fits with the cable colors (black on each side)
- if we map the red to pin 13 (3.3v power) then we end up with (this is highly speculative):

Wild Guess Attempt (considering all the info we have so far):

1-  USB Ground - Black
2-  ?          - Brown
3-  USB D+ ?   - green  (twisted pair with white)
4-  USB D- ?   - white  (twisted pair with green)
5-  USB power? - Red
6-  ?          - Orange
7-  DTR        - unconnected
8-  RTS        - unconnected
9-  RxD        - unconnected
10- TxD        - unconnected
11- GRD        - yellow  (Green+Red leD?)
12- PLTRS1     - green   ("enable" or "reset" - active low?)
13- 3.3v       - Red
14- Ground     - Black

« Last Edit: November 20, 2010, 12:28:08 PM by bernard » Logged
bernard
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« Reply #19 on: November 20, 2010, 04:16:24 AM »

Another thought: If the board really supports USB and serial I would suppose it only does one thing at a time.  So maybe there is some sort of USB/serial selector pin/mechanism.
« Last Edit: November 20, 2010, 12:18:11 PM by bernard » Logged
bernard
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« Reply #20 on: November 20, 2010, 06:30:35 AM »

A post about the power supply: -- 3.3v, 5v?

I am carefully inspecting the board photo -- btw it's quite a nice photo -- I know how difficult it is to photograph a PCB clearly because of the low-contrast of the IC markings and highly-reflective items -- and considering it has a glossy plastic on top!  nice job!  Smiley

One thing I noted is that it seems that a zener diode is not installed (labeled ZD1).  That might indicate the following:  considering the Zener diode being in a rather "large" package, it maybe be used (along with a resistor in series) for converting the 5v to 3.3v. Since the part is not installed, it is plausible that the Wacom controller is currently "configured" to work off 3.3v instead of the USB 5v. After all, USB power does not need to be connected -- especially "inside" a computer where you have all the signals directly from the computer power supply.

Note that the zener seems to have a little "k" -- which could indicate the "cathode".

To verify that, would involve checking how the USB power (pin 5 in theory) is wired along with the 3.3v and the zener.  The theory would say that the 3.3v (pin 13) is connected to the ZD1 pad near the letter "k" (cathode). The 5volt (pin 5) would be also connected there but through a resistor (i.e. in series).  The other ZD1 pad should be going to ground.  There is a third pad surrounded with by a lot of "green" which I think it is just there to dissipate heat (that green area should be "ground" I suppose) -- since Zener only have 2 pads.

* zener3_3v.png (3.47 KB. 345x221 - viewed 565 times.)


The 5v power (pin 5) appears to be connected to a larger-than-the-others capacitor (C24) -- which could indicate an input power "noise" cancellation -- it is really difficult to see from the photo since there is a wee bit of "blurp" in that area.

In other words, if what I say here turns to be true, you are going to need to feed 3.3v (instead of 5v that USB provides).  Also, it would help confirm that the pin 5 is really a 5v supply power.

 

« Last Edit: November 20, 2010, 12:45:31 PM by bernard » Logged
bernard
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« Reply #21 on: March 17, 2011, 04:59:53 PM »

@farinasa : Any progress here? 

I am about to seriously embark on interfacing serial-based TabletPC (Penenabled) boards and "convert them" to a USB Wacom device. (I more or less finished doing it for ADB boards).  I need to find-back what I have in terms of wacom sensors in the basement.

I also need more info on the pinouts of all of these boards.

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bernard
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« Reply #22 on: March 21, 2011, 06:37:03 PM »

If we find out that this is working off the USB but cannot use the USB 5v (you would need to feed 3.3v), this can be accomplished with a 1$ surface mount part (http://www.pjrc.com/store/mcp1825.html) that you might get away connecting without PCB. (there are alternatives, but I know this one works). Or if we ever find the appropriate missing zener diode to solder on the board or a viable replacement.

I think I will try to get one of your board (or similar) to help out. If we make this work, it could mean an awesome new source of really cheap wacom tablets.
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bernard
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« Reply #23 on: June 28, 2011, 03:46:25 AM »

USB it is! Smiley

I finally got aroud to try this board.

So that SU-13W02E-03A board definitely works with USB. Tried with the 2007 (5.05-7) wacom driver on XP.

I had an external 3.3v supply, but the rest (GND, D+ and D-) are directly connected to a USB port. Nice!

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farinasa
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« Reply #24 on: August 25, 2011, 07:04:12 AM »

Hey bernard,

This project has creeped back into my interests.  How accurate is the pin chart listed above?  Are you saying you connected pins 1(GND), 3(D+), 4(D-), and 13(3.3v)?  Also looking at the teensy now.  If the 3.3v regulator was added to it, would that essentially make this plug and play?

Regulator: http://www.pjrc.com/store/mcp1825.html
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bernard
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« Reply #25 on: August 25, 2011, 08:24:17 AM »

yes, it is plug-and-play. Actually, you would not even need the Teensy -- just the voltage regulator alone (or another electronic circuit that can generate 3.3v out of the USB 5v).  

The voltage regulator alone is a small 1$ part sold at prjc.com (it is the one you are referring to).  You just have to connect the GND, the USB 5V and 3.3v spits out on the third connection.  Smiley
« Last Edit: August 25, 2011, 12:16:35 PM by bernard » Logged
AbeOwitz
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« Reply #26 on: April 01, 2012, 07:31:01 PM »

Just a quick note to say thanks to your forum and wiki, I got my wacom board working, at least on the serial side.  Smiley

I bought a used Toshiba Protoge M200 to reverse engineer.  It uses Low Pin Count (LPC) interface for its serial port.  

It uses the SU-019-C01 Wacom board.

The following boards also work as serial boards and have the same connector & pinouts:
SU-012-X03
SU-035-A01
SU-031-X02
(purchased through pchub)

Have not figured out USB.

Here's a summary of how to wire for Serial.

1 GND
2 NC
3 NC
4 NC
5 NC
6 NC (LED + resistor works here.  Not pictured)
7 NC or GND
8 NC or GND
9 TTL Serial Output from Wacom
10 NC
11 GND (will not work unless grounded.)
12 NC
13 3.3V
14 GND

EDIT:  It seems it intermittently starts up with 12 connected to 3.3v.  Leaving 7 & 8 open doesn't seem to make a difference.

That's 3 X 10ohm resistors there, since I don't have a 33ohm.  This brings it down to 3.0V, but it still works.  20ohm works also, but the diode (1N4728) gets warm.  10 or less and it's hot.  Which makes sense since 5ohms would put it at max current.


« Last Edit: April 01, 2012, 11:30:04 PM by AbeOwitz » Logged
bernard
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« Reply #27 on: April 02, 2012, 04:09:42 AM »

Welcome abe0witz!

What is that LPC thingy? How did you know it is called like that?

For ISDV4, you need a spot to connect the serial data going into the tablet normally..?
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AbeOwitz
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« Reply #28 on: April 02, 2012, 09:43:16 PM »

LPC:
http://en.wikipedia.org/wiki/Low_Pin_Count

On the Toshiba Protege M200, this provides the UART/Serial needed to connect to the Wacom.  In Windows Device Manager, the Wacom is listed as an LPC device.

Not a big deal, the Wacom board is still serial. 

ISDV4 wise, the above is minimal for getting the board to spit out data.  I'll likely need TXD, RTS and DTR to talk to it.

I'll keep hacking at it.  Smiley

I appreciate your board and wiki!  Thanks!  Very useful.  I hope I can contribute back soon.  Smiley  (I'm still learning, too....) 
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bernard
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« Reply #29 on: April 02, 2012, 10:00:12 PM »

You seem well equipped (a scope!) and appear to know about electronics Smiley  yay!

OK. So it sounds like "LPC" seen by Windows just because it is hooked through a Super I/O chip which is often hooked to a LPC bus.  Super I/O chip is a often what is used inside laptops/motherboards for the serial ports (even internal ones).  Like you said, it appears that the Wacom board has nothing to do with LPC.

RTS/DTR: you do not really need those. But you still need to make sure they are always "active" (not in a state that it will "stop" the data from flowing).  Depending on the signal, either grounding it or VCCing it if there is no pull-up/pull-down doing this already.

I assume you saw our wiki, since you mentioned it.  We saw weird variations between the Wacom boards. Does your board has a vacant ZDx part like we saw on others?

How did you know these boards are compatible?
SU-019-C01
SU-012-X03
SU-035-A01
SU-031-X02
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