We purchased a BeagleBoard Rec C3 board last summer and were able to
get it to boot into Angstrom. We would like to get a touchscreen
working with the beagleboard, so we ordered the screen available here:
We soldered it on and it is powered (ie the backlight is lit), but we
are unsure of how to get any video display on it. We emailed the
SpecialComputing people several times, with specific information, but
all they ever respond with is "We currently don't support Angstrom on
RevC4, just RevC3", and then don't bother to respond beyond that (even
though we *have* the Rev C3 board).
Sorry you are having trouble getting answers. Thanks for pointing that out.
Few points here:
1. There should be no reason why it won't work on the C4. As Gerald pointed
out, the only differences do not affect the LCD. The main thing is be sure
you have a U-boot that turns on the right regulators on the TPS/TWL part. The
Angstrom-esque way appears to be to hack U-boot for pinmux which makes it
hard when future hardware needs an updated U-boot (i.e. C3 vs C4).
2. I am a distro agnostic person and the reactions from the distro in question
was no interest in taking a patch. Having said that, this is what you will
need to do to get it working in Linux.
a. Setup your pin mux per the description below. There are at least 2 pin mux
configuration that will work. (Dimmable vs non Dimmable backlight).
b. Configure the timing for a 480x272 by 24bit display. A pixel clock around
6-9MHz should work fine. At one point the DSS2 code had a suitable panel
definition but that seems to have been removed in the K-O commited version so
you will need to add that. You might try the dvimode hack but that is not a
very clean approach. If you are using the old driver, just create a new C
file to define the timing.
c. Define the screen enable/disable functions along with the backlight
enable/disable functions in your board file. Add the structure to the board
file so DSS2 can call them.
d. Use the TSC2046 driver on McSPI4 with GPIO157 as the IRQ.
Pin usage information:
GPIO144 - Backlight enable. This line is also the PWM output so the backlight
can be dimmed with software. Use the pinmux to select method desired.
GPIO 162 - LCD enable. This will let you disable the display for PM reasons.
GPIO 157 - This is the IRQ for the TSC. Set this up as an input.
McSPI4 is used as the TSC interface.