What Pen are you using? (EA800)

Discussion in 'Asus (Android)' started by thescreensavers, Jul 30, 2011.

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  1. SH0DAN

    SH0DAN Pen Pal - Newbie

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    Hello BlacKnight,

    I reconsidered the sourcecode within input-raw.c. If the touchscreen driver or hardware of the eeeNote supplies more than 256 pressure steps and onyl the processing within input-raw.c limit the range to 0-255 there should be a rollover when pressing a stylus with more than 256 steps onto the screen. If the line width within the notes application does not have a point where it suddelny gets thin again, the hardware or the driver limits the pressure range.

    If the line width within the notes application is not like this when using a 1024 pressure steps pen I don't think the input pressure range can be extended because it's limited by the driver or even the hardware...

    Code:
           ^
      L  W |    /|   /|
      i  i |   / |  / |
      n  d |  /  | /  |
      e  t | /   |/   |
         h +------------>
            Pressure
     
  2. BlacKnight

    BlacKnight Scribbler - Standard Member

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    I agree with your comments. But when you use a 1024 level pen it just saturates at 255, so it's probably a hardware saturation limit. When I get a minute I'll try and get the part number of the digitiser & see if I can find a data sheet.

    If it is a hardware limit then a possible work around to get the Note app pencil/pen tools working better might be to implement a "hard" scaling, where the output increases more slowly for low input pressures, and more rapidly for large input pressures. This should have the effect of expanding the range for low pressures, which I think would give a more responsive feel to the drawing tools. Many of the Wacom tabletPC drivers have a soft/hard setting for the pen response. Here is a link about an example utility that does this for tabletPCs.

    <edit>
    The main ICs used in the digitiser are Wacom WA5001 and W6010. Unfortunately I can't find any data sheets for them. I expect they are only issued to OEMs under NDA.

    However, I found a description of the Wacom comms protocol ISD V4 which seems to match the code in input_raw.c. It looks like the comms protocol supports pressure resolution up to 10 bits (1024 levels). However, there doesn't appear to be a way of configuring the digitiser resolution - you're supposed to query it to get the pressure resolution. But since the Eee Note firmware is only intended to run on a single hardware platform it may not bother, and just assume 8-bit pressure resolution. There may be an initialisation module somewhere that does this, but I haven't spotted it yet.

    So, if we assume that the source file input_raw.c is the one being used on the Eee Note then it looks fairly conclusively that the Wacom hardware is limited to 8-bit pressure resolution. As a final check one could write a small utility to querry the pressure resolution from the hardware, but I don't think it's worth doing this because the result is likely to be 8-bit.
     
    Last edited by a moderator: May 18, 2015
  3. stylus800

    stylus800 Pen Pal - Newbie

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  4. BlacKnight

    BlacKnight Scribbler - Standard Member

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  5. Jamie-B

    Jamie-B Scribbler - Standard Member

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  6. stylus800

    stylus800 Pen Pal - Newbie

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  7. BlacKnight

    BlacKnight Scribbler - Standard Member

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    I don't think so; I think only UP (and now SP) series pens are compatible with Penabled devices like the Eee Note. Not LP series. None of the Office Depot pens appear to be UP series.

    See this post for a link to a compatibility chart.
     
    Last edited by a moderator: May 18, 2015
  8. stylus800

    stylus800 Pen Pal - Newbie

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    Last edited by a moderator: May 18, 2015
  9. BlacKnight

    BlacKnight Scribbler - Standard Member

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    I understand that some suppliers won't ship to Italy because of problems with postal reliability. On Amazon the Toshiba pen is usually a bit cheaper. The cheapest pen I've bought here in the UK is the Taiwanese Gateway pen on eBay. Some American users report getting the Axiotron pens very cheaply (on eBay I think).
     
    Last edited by a moderator: May 18, 2015
  10. etienne

    etienne Pen Pal - Newbie

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    Well, here in canada, Fujitsu digitizer pen cost around 40$ each (I think). Well I bought mine 80$ for two.
     
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