need suggestion for a 4.3" AMOLED display module / Driver - Page 1
Forum section: electronics / projects

author: kyndal
author_rank: Regular Contributor
timestamp: November 04, 2016, 07:09:29 am
content: Hi Guys.I am working on a hobby project. where my current setup uses a LCD panel.But i need FAR FAR better direct sunlight readability.so I'm looking to replace the LCD with a bright AMOLED panel of same size and resolution.my current panel is a 4.3" 480x272 LCD with RA8875 driver, controlled over SPIhttp://www.buydisplay.com/default/4-3-tft-lcd-display-module-controller-board-serial-spi-i2c-mcuAdafruit has a small driver board with the RA8875 chip for the same generic cheap LCD'shttps://www.adafruit.com/product/1590but I'm having a hard time finding a similar "user friendly" "panel + board module" combination.from any of the usual suspects.I can only find bare AMOLED modules. with the flatflex connector.. needing an adapter board and supporting circuitry.which is a bit over the hoped level of complexityAny suggestions out there, where to get a "user friendly" module with a 4.3" AMOLED panel, i2c or SPI interface.and if the stars lign up... a bit of code snip lets / library / driver ?worst case i guess. i may just try to use the same panel used in the beagleboard "beagle touch"at least there is a bit of linux driver code to start with..any pointers on this would be greatly appreciated.ThanksRune

author: bktemp
author_rank: Super Contributor
timestamp: November 04, 2016, 10:24:16 am
content: Quote from: kyndal on November 04, 2016, 07:09:29 amThat does not make any sense. If you need sunlight readability, use the sun as the light source: There are many LCDs with reflective mode.Using OLEDs is probably the worst solution at high ambient light conditions, because their lifetime is pretty limited, especially at high current levels that are needed to make it sunlight readable.If you need a full colour TFT LCD, sunlight readable TFT LCDs exist. They use either a powerfull backlight, or they use reflective mode. Reflective mode TFTs look quite bad compared to the normal transmissive mode TFTs, but they are perfectly sunlight readable even without backlight. Your biggest problem is probably finding a "user friendly" assembly for such a specialised display.

author: timb
author_rank: Super Contributor
timestamp: November 04, 2016, 11:56:32 am
content: A Sharp Memory display would be ideal. They do have a 4.3" model, but it's not color. They are *very* readable in the sun! (Some models actually use a special liquid polymer that makes the pixels appear metallic; with all pixels turned on you can use it as a mirror!)

author: Fungus
author_rank: Super Contributor
timestamp: November 04, 2016, 03:03:56 pm
content: Quote from: kyndal on November 04, 2016, 07:09:29 amAMOLED won't work. LEDs can't compete with the sun.Have you looked at e-ink displays?http://www.ebay.com/sch/i.html?_nkw=e-ink+displayYour post suggests battery power. Those things use zero battery once the image is uploaded (you can actually disconnect the battery and the image will remain).Downsides: A bit slow to update and no color.

author: kyndal
author_rank: Regular Contributor
timestamp: November 05, 2016, 10:23:46 am
content: thanks for all the replies guys.i guess i should clarify the requirements a bit further..it will not be "direct sunlight" as in standing in a field with the back to the sun.but it is "critical" thats its readable at all times (so overkill)the display will be mounted in a piece of moving equipment almost flat horizontal on the floor against the windowhighly exposed to the sun in pretty much worst case scenario. and at some angles the sun completely blacks out the prototype display I'm usingi do not need "full color"if there are very high visibility displays. at color trade-off i only need a few standard colors say black,white,red,yellow,green etcGray scale is technically not out of the question. i suppose..for this application readability is more critical than neat colorsE-ink wont work however. its for live readings on a "sweeping needle" analog gauge like graphicneed much higher refresh rate.i suppose i didn't fully think through the OLED. lifetime issues.. this display will have alot of static elements burning in.power demand. not an issue howeverso i guess. sunlight readable. transflective LCD might be worth a shot..i guess i can start by finding a compatible transflective panel with same interface as the one used with the RA8875i believe its a standard interface ? 40 pin PFC connector.an see how much current the leds can take before it catches fire.1 VLED- LED Cathode2 VLED+ LED Anode3 GND Ground4 VDD Power Supply5-12 R0~R7 Red Data13-20 G0~G7 Green Data21-28 B0~B7 Blue Data29 GND Ground30 PCLK Clock31 DISP Disp="on" when pin 31 is connected with high-level. Disp="off" when pin 31 is connected with low-level.32 HSYNC Horizontal sync input in RGB mode. (Short to GND if not used)33 VSYNC Vertical sync input in RGB mode. (Short to GND if not used)34 DE Data Enable35 NC NC36 GND Ground37 XR X_ Right (This pin is used for resistive touch panel )38 YD Y_ Down (This pin is used for resistive touch panel)39 XL X_ Left (This pin is used for resistive touch panel )40 YU Y_ Up (This pin is used for resistive touch panel)/Runeedit: Looks like i can find (probably) compatible 1000 and 1500 cd/m2 transmissive panels.but im not sure what those value mean in regards to brightness / sunlight readability

author: timb
author_rank: Super Contributor
timestamp: November 05, 2016, 11:24:02 pm
content: Quote from: kyndal on November 05, 2016, 10:23:46 amHere's a 4.3" Sunlight Readable 256k Color TFT.They're a bit expensive in low quantities, but it gets the job done! (You'll need an MCU capable of driving a standard 24-bit RGB panel; or you can use the RA8875 as a controller. Most 24-bit color TFT displays from 3.2" to 7" use a 40-pin FPC with a standard pinout.)I'd also look into the Sharp Memory LCD displays. They're ultra low power and read just like a piece of paper in the sun. Interface is via SPI. They've got a 2.3" and 4" model that might work well for you. They've also got a 1.5" color display, but that might be too small.The Sharp displays bridge the gap between ePaper and traditional LCD technologies. Basically, the pixels of the LCD itself act as the frame buffer (hence why it's called a Memory LCD) and will retain the data without power, all you have to do is reverse the polarity of VCOM once every second to keep the image visible; doing so uses only a couple of uA of current. This can be done by physically toggling a pin of via a command over SPI.They're also very fast, capable of frame rates approaching 60fps without any blurring. These are the displays used in the Pebble (and a few other) types of smart watches.Finally, don't dismiss ePaper displays outright. They *can* actually display motion at around ~15fps without blurring. I've got a 2" ePaper display kit here from Pervasive Displays and there's a demo for it that shows a fan icon spinning and a gauge with a needle moving back and forth. I wouldn't call it fluid, but it's actually very useable.(They can do this because, unlike what you may have seen on your Kindle, an ePaper display doesn't actually have to "flush" the entire display every time something changes. The only reason the Kindle does that when changing pages is to prevent artifacts when moving between entire pages of text. That's not an issue when you're only updating a small portion of the display at a time.)

author: timb
author_rank: Super Contributor
timestamp: November 06, 2016, 10:38:50 am
content: Quote from: blueskull on November 06, 2016, 08:22:26 amObviously it's a transmissive design, yes. Though, it's not a PSP display (even though it may be the same size).Their spec is very conservative, you can easily drive those LEDs at 50mA, which can give you a brightness of close to 1000cd/m2. It also uses an improved (compared to cheaper displays) 3M matte anti-glare coating. Plus it's designed specifically to take the extra heat required by the brighter LEDs (plus added heat from being exposed directly to the sun).You can always try boosting the backlight current on a cheaper Alibaba 4.2" TFT, but I'd do rigorous testing in actual sunlight (or under a heat lamp) to make sure it doesn't fail due to heat before you deploy it.

author: timb
author_rank: Super Contributor
timestamp: November 06, 2016, 11:53:32 am
content: Quote from: blueskull on November 06, 2016, 10:48:25 amAh, yeah, fair enough on point 3! I misread your post and thought 30mA was outside maximum ratings.Newhaven's stuff is overpriced (in single quantity), for sure, but it's generally high quality with a good warranty. They also ship from US, so it's nice if you need something fast for a prototype. I generally don't buy TFT's from them, as I can get good quality from BuyDisplay.com a lot cheaper. However, Newhaven's OLEDs are nice little custom jobs on their own boards with bezels, plus 2.54mm headers, which is, again, nice for fast prototyping!Anyway, boosting a PSP display's current plus an anti-glare filter might work well for the OP. My warning was more about the fact that there's a lot of non-OEM replacement PSP panels floating around out there that might not have the same specs as the Sharp branded original.