[Build] About those touch panels

[nils at shkoo.com]

>From reading the source for drivers/input/touchscreen/inexio.c in the 
linux kernel, it looks like it should should work with the format of the 
messages that are coming from the touch screen, albeit it might have a few 
spurious debug messages and it might miss really short taps.  (It looks 
like the driver is not prepared to deal with the 4-byte periodic messages 
messages)

What happens when we try to use this driver?

-nils

On Thu, 10 Sep 2009 nils at shkoo.com wrote:

> 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
>> 
>