[Build] About those touch panels

[nils at shkoo.com]

Here are the messages I've been getting over the serial of the 
touchscreen.  I got these through the usb port, not from hooking up the 
rs232.  I don't know where my vga cable is so I didn't try to connect up 
the display part, so I don't know if that affects the output.

This seems to be a keepalive of some sort:

4 bytes:  82 04 0a 0a
4 bytes:  82 04 0a 0a

This is from a touch in the upper left corner:

5 bytes:  81 01 03 04 7e
5 bytes:  81 01 3c 04 7e
5 bytes:  81 01 76 05 04
5 bytes:  81 01 03 07 43
5 bytes:  80 00 ff 00 ff

This is from a touch in the upper right corner:

5 bytes:  81 79 7a 05 21
5 bytes:  81 79 73 05 00
5 bytes:  80 00 ff 00 ff

This is from a touch in the lower left corner:

5 bytes:  81 02 31 7d 3d
5 bytes:  81 02 62 7c 1f
5 bytes:  81 02 1b 7c 1f
5 bytes:  80 02 0f 7c 1f

This is from a touch in the lower right corner:

5 bytes:  81 7a 71 77 04
5 bytes:  81 7a 3c 74 66
5 bytes:  80 00 ff 00 ff

So, I think here are what bytes mean that we need to worry about:

0x80: finger-up

0x81: finger-down (or moved), followed by 2 bytes x position (big endian), 
then 2 bytes y position (big endian)

So, the protocol looks pretty straightforward.  I don't have a linux box 
handy so it's tough to try to figure out the gpm setup.  Maybe I'll try to 
scrounge one at some point.

-nils

On Thu, 10 Sep 2009, dpc wrote:

> Andy Isaacson <adi at hexapodia.org> writes:
>
>> On Wed, Sep 09, 2009 at 09:19:01PM -0700, nils at shkoo.com wrote:
>>> I'll take one of these home tonight and hook it up to serial and try to
>>> figure out what it's outputting.
>>
>> I tried hooking it up to USB.  The results were not encouraging, it
>> kept detaching and reattaching to my USB port, as I documented on the
>> wiki:
>> https://www.noisebridge.net/wiki/Inexio
>
> it has been a while, but i recall that these messages don't mean that it
> is actually (re)attaching, but rather that the configuration set failed
>
>  [20887.891836] usb 3-2: new full speed USB device using uhci_hcd and address 14
> ...
>  [20888.071558] usb 3-2: configuration #1 chosen from 1 choice
>  [20955.608590] usb 3-2: USB disconnect, address 14
>  [20960.312903] usb 3-2: new full speed USB device using uhci_hcd and address 15
>
> the probe state wasn't 'poisoned' (for lack of a better word) so the
> unconfigured device is retried.
>
> \p
> ---
> There is no death, there is only me, me who is going to die. - Malraux
>