SMALL VGA displays for use with props?
xanatos
Posts: 1,120
Inquiring to see if anyone has a good preferred source for small (like 4" max!) LCD, or OLED displays that are VGA ready?· Preferably something readable in sunlight and dark.
Thanks for any of your suggestions/sources!
Dave
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Thanks for any of your suggestions/sources!
Dave
·
Comments
-Phil
and sync inputs should work with a little tweaking. The ones I have don't have high resolution but for such
a small screen you can't see it anyway. Even considering the fact that I am planning to use the ones I
have to make a Virtual Reality Headset even though they only have CGA resolution.
It seems to me that they can be connected before the resistors on the usual prop VGA port since they
have 5 bit digital inputs for each of the RGB channels, and only two need to be connected with the usual
VGA driver (which may need to be slowed down to 4 Mhz pixel clock and less pixels to output).
The pixel clock might be the only extra signal needed to send to the LCD.
Odd voltages maybe needed too, including high voltage for EL/CFL backlight and bias voltage for contrast control.
It seems to me that many at least around Y2K color LCDs used parallel digital RGB inputs,
as the screen from one broken laptop had 8-bit RGB inputs that I was able to find the datasheet for.
And don't forget the Prop uses 3.3V and other things use 5V. Shouldn't be a problem for LCD signals
because the 5V logic will accept 3.3V as a binary 1 on it's INPUTS as if it were 5V. It's the 5V logic
from external devices that should be carefully dropped to 3V before going to Prop inputs.
Dave
Not all 5V panels will accept 3.3V as high, sadly. A simple ACT or similar buffer ('244, 245 etc) will suffice to rise the voltages.
The complication with this panels arise from the fact that you need a clock signal that is synchronized with the data. Generating this signal could be tricky. Rayman has made (or is doing) a driver for a 480x272 TFT. This particular TFT needs a ~9 MHz clock, so it is doable. I'd use a FPGA anyways because they are cheaper than a propeller.
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Visit some of my articles at Propeller Wiki:
MATH on the propeller propeller.wikispaces.com/MATH
pPropQL: propeller.wikispaces.com/pPropQL
pPropQL020: propeller.wikispaces.com/pPropQL020
OMU for the pPropQL/020 propeller.wikispaces.com/OMU
I already showed it somewhat working at the Expo in Ohio! (I've also started a few threads on it)
I'm also going to be selling the bare LCD shortly and posting notes and code on how to interface to it...
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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm
Dave
I have just figured out how to use a small LCD screen found in the "Miuchiz Monsterz" original hand-held games, and successfully rendered to it using SPIN.· These are not the newer "v2.0" devices with a clam-shell, these are the original devices without a clam-shell cover.
I have found that those old 'Miuchiz' games can be found for pretty cheap these days.· I've picked up 4 of them now for $5.00 each, around town, and on eBay.·
The LCD itself is 98 pixels x 67 pixels, RGB, with backlight (65K colors).· CSTN.· 1.33" diagonal (yes, qute small), and has an on-board LCD controller ST7626.
The datasheets were easy to google for, unlike most LCD's I've tried to find:
search google for:· PH9867C-001.pdf· (The physical LCD device)
search google for:· ST7626.pdf (The on-board controller chip)
The LCD has on-board VRAM, and a CPU-like communications interface, making it quite easy to program. (chip-select, address, 8-bit data, read/write signal, etc).
The LCD itself is even mounted in the game, using a socket, so is easily removed without any damage.· A few compatible sockets are available at DigiKey:
DigiKey Part# 609-1949-ND is my favourite for prototyping.
DigiKey Part# 609-1156-1-ND is a surface-mount option.
The LCD uses 3V-3.3V logic, and a 10.0V "V0" (LCD driver power).· The LED is driven just as you would any normal LED.· I used a 1K resistor to the 10.0V source.
This is the first Propeller code I've written.· I picked up the programming in one evening, and am SUPER IMPRESSED with the propeller chip!!
(spin code attached)
Hope someone else finds this information useful...
··· Roger
Post Edited (Roger Milne) : 9/16/2009 6:06:43 AM GMT
Dave
One for screen detail, the other·for size reference (cough-don't-look-at-the-wiring-cough).
··· Roger