Does anyone know what the best way to interface the Rev. C board with
an LCD display is (like maybe PSP screen)?
You will need to create a buffer card that will translate the levels to those that matches the LCD of choice. In addition, the board will need to translate the voltages from the 1.8V level to the level as needed for the desired display and provide the connector that connects to the LCD panel. A PSP LCD can indeed be connected to the expansion header. All of the signals are there, you will just need to do the level translation and connector matching…
Gerald
Hello,
you said all signals are there but my LCD needs:
1 VSS GROUND
2 VSS GROUND
3 VCC +2.5V POWER SOURCE
4 VCC +2.5V POWER SOURCE
5 R0 RED DATA SIGNAL (LSB)
6 R1 RED DATA SIGNAL
7 R2 RED DATA SIGNAL
8 R3 RED DATA SIGNAL
9 R4 RED DATA SIGNAL
10 R5 RED DATA SIGNAL
11 R6 RED DATA SIGNAL
12 R7 RED DATA SIGNAL(MSB)
13 G0 GREEN DATA SIGNAL (LSB)
14 G1 GREEN DATA SIGNAL
15 G2 GREEN DATA SIGNAL
16 G3 GREEN DATA SIGNAL
17 G4 GREEN DATA SIGNAL
18 G5 GREEN DATA SIGNAL
19 G6 GREEN DATA SIGNAL
20 G7 GREEN DATA SIGNAL(MSB)
21 B0 BLUE DATA SINGAL(LSB)
22 B1 BLUE DATA SIGNAL
23 B2 BLUE DATA SIGNAL
24 B3 BLUE DATA SIGNAL
25 B4 BLUE DATA SIGNAL
26 B5 BLUE DATA SIGNAL
27 B6 BLUE DATA SIGNAL
28 B7 BLUE DATA SIGNAL
29 VSS GROUND
30 CK CLOCK SIGNAL TO SAMPLE EACH DATE
31 DISP DISPLAY ON/OFF SINGAL
32 HS HORIZONTAL SYNCHRONIZING SIGNAL
33 VS VERTICAL SYNCHRONIZING SIGNAL
34 NC NC(THIS PIN SHOULD BE FIXED TO GND)
35 AVDD +5V ANALOG POWER SOURCE
36 AVDD +5V ANALOG POWER SOURCE
And on Beagle Rev C. there are:
1 DC_5V PWR DC rail from the Main DC supply
2 DC_5V PWR DC rail from the Main DC supply
3 DVI_DATA1 O LCD Pixel Data bit
4 DVI_DATA0 O LCD Pixel Data bit
5 DVI_DATA31 O LCD Pixel Data bit
6 DVI_DATA2 O LCD Pixel Data bit
7 DVI_DATA5 O LCD Pixel Data bit
8 DVI_DATA4 O LCD Pixel Data bit
9 DVI_DATA12 O LCD Pixel Data bit
10 DVI_DATA10 O LCD Pixel Data bit
11 DVI_DATA23 O LCD Pixel Data bit
12 DVI_DATA14 O LCD Pixel Data bit
13 DVI_DATA19 O LCD Pixel Data bit
14 DVI_DATA22 O LCD Pixel Data bit
15 I2C3_SDA I/O I2C3 Data Line
16 DVI_DATA11 O LCD Pixel Data bit
17 DVI_VSYNC O LCD Vertical Sync Signal
18 DVI_PUP O enabled. Can be used to activate
circuitry on adapter board if
desired.
19 GND PWR Ground bus
20 GND PWR Ground bus
1 3.3V PWR 3.3V reference rail
2 VIO_1V8 PWR 1.8V buffer reference rail.
3 DVI_DATA20 O LCD Pixel Data bit
4 DVI_DATA21 O LCD Pixel Data bit
5 DVI_DATA17 O LCD Pixel Data bit
6 DVI_DATA18 O LCD Pixel Data bit
7 DVI_DATA15 O LCD Pixel Data bit
8 DVI_DATA16 O LCD Pixel Data bit
9 DVI_DATA7 O LCD Pixel Data bit
10 DVI_DATA13 O LCD Pixel Data bit
11 DVI_DATA8 O LCD Pixel Data bit
12 NC No connect
13 DVI_DATA9 LCD Pixel Data bit
14 I2C3_SCL I/O I2C3 Clock Line
15 DVI_DATA6 O LCD Pixel Data bit
16 DVI_CLK+ O DVI Clock
17 DVI_DEN O Data Enable
18 DVI_HSYNC O Horizontal Sync
19 GND PWR Ground bus
20 GND PWR Ground bus
Which LCD Pixel Data bit is the Right Color Bit for my LCD?
Is this a certain WQVGA screen used in a common hand held toy? The signals and
voltages sure look like it. If so, I can confirm that it definitely are there
and it works.
What you will need to decide first is how do you want to control the LCD and
backlight (enable/disables for both, shared, acceptable interactions with the
DVI output). With pinmux tricks you can recycle some of the lines or give up
a color line or two to use it as a GPIO to control the LCD. Or you can pull
some of the controls off the main expansion header. 24bpp is doable with the
signal but you loose a bit of granularity in the controls as far as being
able to do PM and/or switch with the external DVI signals. Once you have that
figured out then figure out the actual hook up. The allocation of the color
lines are documented in the TRM and will vary depending on how you have
software setup (16bpp/18bpp/24bpp). This setting is seperate from the frame
buffer settings as the DSS can translate to some extent. Main thing is design
how you want to control the LCD before hand.
Btw, do not forget the DVI_PUP signal is at 3.3V. Or there may be some
surprises. 
Thanks for the fast reply!
Its an 480x272 PSP-compatible Display!
I'am new to all that linux stuff.
I'am normaly control 4-line Displays with 8bit or 4bit Interface.
Can you give me some detail information on driving this display with
beagle?
I know that i need the right voltages for the LCD.
But where i can see the kernel part where the lcd lines are
configured?
All signals are there for this display. I just finished designing an adapter card for it and it goes into layout later this week.
Gerald
You need to tell the display driver the right clock timings for this
to work. Also note that hsync and vsync are inverted (it took me a
little while to figure this out) I actually edited the kernel source
code to make mine work, but maybe you can do it with a kernel
parameter (the kernel I had didn't support this display yet)
I would be curious to know if the psp display can work at 1.8v..
since it works normally at 2.5v levels it might actually work without
translators (although out of spec)
Sean
Can you post the schematic.
I think i'am not the only one who want to use such display.
I have level translators on my board. They are definitely required.
Gerald
Well according to the datasheet, the min Vcc is 2.3, and logic high is
.8*Vcc which would be 1.84. It looks like it wouldn't be quite in
spec, but maybe if you drive it at 2.0-2.3 volts instead of 2.5 then
you could get away without level translators.
Sean
I do not post untested schematics. Call it a personality flaw!
Gerald
Keep in mind that there is another devcie already on those signals.
Gerald
I think there is only the hdmi connector?
No, there is the HDMI framer on it. It loads down the signals as a load. The buffer is really needed to clean up the signal. If the destination was 1.8V, it would be OK, but if you are looking to “get by”, it won’t be enough without the buffers.
Gerald
Slightly tangential question -
With the current layout, what is a conservative estimate as to the number of
additional pF of drive that is available on the LCD and expansion headers?
Trying to backout how much cabling can be reliably used.
I have no idea other than to say, not a whole lot. But, that does not count the connectors either. But, I wouild not recommend going the cable route due to the 33 ohm series resisitors that are there and the load of the TFP410. There is not a lot of drive out of the OMAP3530. If you just had to go a cable, keep it short and add buffers on the other end.
Gerald
Anyone get the psp screen working? Just got Rev C2. I was interested
in hooking one up to the board (maybe the touch screen overlay would
work too?) From what I was reading, I'm guessing that you cant just
hook up the screen to the board and cross your fingers. Sounds like
there is some kernel patching and circuit work to be done.
That is correct. You will need to level shift the control signals from a HW standpoint. There will also be code changes required. The code changes are currently being discussed in another thread.
Gerald
Anyone get the psp screen working? Just got Rev C2. I was interested
in hooking one up to the board (maybe the touch screen overlay would
work too?) From what I was reading, I'm guessing that you cant just
hook up the screen to the board and cross your fingers. Sounds like
there is some kernel patching and circuit work to be done.
Hi,
I have the PSP LCD working and I am not happy with it. You can see it on my
website (see .sig). The only thing good about the PSP LCD is that it is cheap
in single quantities other then that, I can't think of anything good to say
about it.
Most of the PSP support stuff is in the latest DSS2 patch already so the
kernel changes are minimal.
The electronics is straight foward; it is a 1 to 1 wiring through a level
converter. About the only thing slightly complex is driving the backlight
unless you want to use a FET and a large stack of batteries to generate the
26V or so for the string of LEDs.
Got a few extra PCBs lying around that I wouldn't mind selling off as I am not
likely to be doing anything more with the LCD. Reply to me directly for
details.
In case anyone else is interested, some of the issues with this LCD is -
it is multivoltage
it requires a tighter tolerance 5Vpower supply then the beagle per the
datasheet. Testing has definitely confirmed the phrase "undefined behavior"
when it is used outside the LCD datasheet range but within the Beagleboard
range
.
Hello
I have the PSP LCD working and I am not happy with it. You can see it on my
website (see .sig). The only thing good about the PSP LCD is that it is cheap
in single quantities other then that, I can't think of anything good to say
about it.
That's the best point, along with its wide availability : COTS
replacement parts are both cheap and easily available, and should
always be preferred.
Which do you tihnk will sell better - $100 kit, LCD included, that
can be plugged to the bb directly, or a $200 kit which requires
specific LCDs that may or may not be available in the future?
So I'd be interested in a board 
BTW will displaying on the LCD port disable DVI output, or can both be
achieved (with different res and possibly different framebuffers)