LCD Screens

May 29, 2007 at 2:55 AM
Anyone want to share how'd you get your LCD screens to work with the Gumstix?

Share your connections and drivers stories and problems.
May 29, 2007 at 11:26 PM
Hardware:

I first went to Earth LCD and got one of their $99 seven inch touch screens along with a power inverter. I also got the precise details of this LCD and the molex connector it uses. I then bought a hirose connector from digikey for the gumsix (also available from gumstix.com) along with an LCD cable and LCD connector.

Next, I went to pad2pad.com and created a custom PCB using their free software, after very closely making sure that the connections agreed with the schematics on gumstix.org, along with also creating a breakout board which I could use to connect to the breakout gumstix if my design was off. You could actually start this way. I also had to develop the molex connector, because the pad2pad software is lacking.

To put it together, I used the toaster oven soldering technique from sparkfun.com. For the masking, I used scotch tape and an exacto-knife along with very little solder paste. This takes practice.

For the inverter, I made a minor modification to a computer power supply to pull 12 volts. Obviously you would build this into your design, along with whatever other voltages are needed. I currently have 5 and 3.3v on my board.

Software:
I got the datasheet for the display and chose a similar entry in the display driver C code to model it from. One that was passive, not one that was similar in size. I then set the timing, colors, and lines correctly based upon the detailed specifications.

Believe it or not, but this actually worked.

Moving forward:
Because of the success of the first attempt, I am going to use a much better LCD because of how good it looks and how inexpensive it is for the size. After shopping around for some time to find a good resolution display, I coincidentally found the same LCD that is inside the PSP. To save money, I took apart a PSP because this was actually less expensive than a single unit from one of the distributors. Just now, I see that sparkfun.com is offering these for only $65!!! They aren't much less in thousand unit quantities, so this is a steal.

I am new to Platform builder, but am going to do the display driver correctly so that it is a module rather than what I rigged up before.
May 30, 2007 at 6:55 PM
Did you guys develop any drivers for your screens? if so, how did you approach it?
May 31, 2007 at 12:28 AM
I created/modified the existing display driver.

There is an existing driver for a 4 inch sharp display that I added a new entry to for my panasonic 7 inch 640x480 passive display. There were several other entries for various displays in there as well. I also modified the config files to make it available.

Basically you have to set various registers on the pxa255 or pxa270 to the appropriate numbers so that it knows the number of pixels to scan, how much time to spend on each pixel, how much time per line, and other wait periods. There are some other settings in addition to timing that will be obvious to you when you read them. You get this information from the data sheet that comes with the display. (be detail oriented). This isn't too bad since most of the work is already done for you, thanks to this group and drumstix. There is probably some trial and error too, especially if the data sheet is either confusing or not available. I remember having 4 little images of the CE desktop at one point, along with other periods of chaos. I would use longer wait times at first if you aren't sure.

This is what I remember from almost a year ago, so it is less detailed than I would like. I'll update this as I get my new sharp display working. I left my old driver at my last company, of which I no longer work for.

I am in the process of just getting CE to run through virtual display right now, so if anyone has any recommendations on that, please let me know. I'm also waiting on a netCF-vx module that seems to be out of stock, so until then, I am stuck in serial mode (ergh). I am now using a Verdex for USB host support, along with CE 6.0. As a side note, I believe my strange problems in the other thread were related to a damaged gumstix.
Aug 27, 2007 at 10:16 PM
Edited Aug 27, 2007 at 10:25 PM
Enrico: I just posted a message about Custom System. Maybe you can help me?

I'm looking for someone that is able to build custom gumstix system running Windows CE (of course for money).
I'm in the middle of some personal project that require small Windows CE based system. I'm myself software engineer, but not as good when it comes so close to hardware. Hopefully, someone around there will be willing to help me (again for money, unless there is some other interest).
Here are requirements to that system:
1. 600mhz would be ideal, but 400mhz may work too (if this is critical to run WinCE);
2. USB ports in host mode (prefferably USB2.0);
3. Support for USB WebCam driver(or Quick Camera Link if it allows 1m wires to camera (that would be preffered);
4. LCD monitor (and/or VGA/AV output if such solution exists)
5. Ethernet enabled and possibly WiFi
5. Of course smallest factor and weight

The system might be identical to the one described by David Vescovi: http://www.windowsfordevices.com/files/contest-summer06/RVTC.pdf, except it should be possibly faster, have LCD screen and no necessarily communication through BlueTooth.

Cheers,
I

Coordinator
Aug 27, 2007 at 10:53 PM
I have interfaced several LCD including a Sharp 5.7 QVGA, 3.2 in QVGA and VGA.
I would be interested in helping.
Developer
Aug 30, 2007 at 5:04 PM
Edited Aug 30, 2007 at 5:04 PM
I would also be interested in paid help for someone that can interface

- a touch LCD screen (Samsung 4.3" diagonal screen LCD from gumstix.com or something similar)
- 3 control knobs with a connex 400 system
- making the system run on a battery

Let me know,

Thanks
Souhail
Oct 31, 2007 at 4:57 PM
I am yet another person interested in paid help to interface a small screen:

-A Samsung 2" AMOLED screen running from driver S6E63D3.
-8 buttons that trigger keypress events

Ultimately this will need to run a windowless flash application and have buttons that can interact with the app.

Here is some basic info about the driver from the datasheet:
The S6E63D3 is a single chip solution for Gate-IC-less AMOLED panel. Source driver with built-in memory,
gate-IC-less level shifter and power circuits are integrated on this LSI. It can display to the maximum of 240-RGB x
320-dot graphics on 260k-color AMOLED panel. Moreover, the chip supports LTPS panel.
The S6E63D3 supports Qualcomm’s high-speed serial interface, MDDI (Mobile Display Digital Interface) type I,
which is an implementation of client device Video Electronics Standards Association (VESA) standard.
The MDDI is a cost-effective low-power solution that enables high-speed short-range communication with a display
device using a digital packet data link.
The S6E63D3 also supports 18-/16-/9-/8-bit high-speed bus interface to enable efficient data transfer to the GRAM.
There is an external interface. In case of display data, the S6E63D3 offers a flexible 18-/16-/6-bits bus of RGB
interface for transferring the 260k colors display data.

Thanks,
Dave
Mar 30, 2008 at 4:02 AM


dvescovi wrote:
I have interfaced several LCD including a Sharp 5.7 QVGA, 3.2 in QVGA and VGA.
I would be interested in helping.



would be cool if u could giveout gumstix interface binaries for 3.2" QVGA and VGA displays. most apps demands this than the gumstix supplied 4.3" displays