nanogui: Interfacing problem: How do I connect my touchscreen driver to nano-X?
Subject:
Re: [nanogui] Interfacing problem: How do I connect my touchscreen driver to nano-X?
From:
Robin Clark ####@####.####
Date:
4 Jul 2007 09:26:53 +0100
Message-Id: <20070704082620.74027.qmail@web25503.mail.ukl.yahoo.com>
Look for where the mouse driver is read from in the gui you are using.
Then use your driver to send the 'C' stucture for X,Y and P (pressure)
back up to nano-X.
You may have to decide when an end of press has occurred, and send back a P==0
packet to indicate a 'release' event (which most nano-X widgets respond to anyway).
And dont forget to allow the touch screen to settle. The first few milliseconds will always
be wrong in a press because of capacitive effects in the touchscreen and wiring to it.
The readings are pretty noisy anyway and you need to average what you consider to be 'good' or consistent
presses (perhaps 10 to every one sent up). This averaging should be done in the driver.
Nano X does some of its own averaging on what it gets too.
Also the raw adc readings from the 7846 need to be translated into screen coordinates. Look at
nxcal (it also irons out distortions to a certain extent). This builds a simultaneous equation
solver matrix and applies it to the raw ADC readings to give you screen coordinates. Nano-X
does this so your driver only needs to send the raw readings.
nxcal can also 'flip' the screen for you.
Robin
----- Original Message ----
From: Laine Walker-Avina ####@####.####
To: "Wein, Peter ((ext))" ####@####.####
Cc: ####@####.####
Sent: Tuesday, 3 July, 2007 5:35:18 PM
Subject: Re: [nanogui] Interfacing problem: How do I connect my touchscreen driver to nano-X?
On Jul 02, 2007, at 06:02, Wein, Peter ((ext)) wrote:
> Hi all,
>
> I am new here and I need your help! I have recently written my SPI
> driver for connecting my touch panel controller ADS7846n to the
> kernel on my ARM9-Board (NS 9360). Because printing of x and y
> coordinates on my debug screen is very boring and does not help
> on, I am now looking for the interface to connect it to the (nano)-
> X-Server. Actually I did not find enough useful info on the www.
> Can anybody of you give me a hint where to look? In which form do I
> have to present my open, read and write functionality for the
> server? Which are the arguments? And in which way do I have to
> modify what config file...
>
> I appreciate any hints.
>
>
> Mit freundlichen Grüßen
>
> Peter Wein
The generic touch screen driver in drivers/mou_touchscreen.c will
probably work for you. If your kernel driver uses the /dev/ts device
file, then you may just be able to use one of the available
touchscreen modes. Look at the headers in devices/touchscreen_*.h to
see how they work.
-Laine
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