5 ms·
> 320 x 240 Resolution Aside from the fact that's for an arduino, which probably mean very low power available, does anybody knows why all those hobbyist LCD a
by ama729 13y ago
> 320 x 240 Resolution
Aside from the fact that's for an arduino, which probably mean very low power available, does anybody knows why all those hobbyist LCD are so low in term of resolution?
It seem impossible to find something higher than VGA on mouser or even Alibaba, much less a reasonably priced HD screen. Where are all those glorious smartphone screen?
(I'm talking about small screen, but even larger one are not that much better)
- gerbal 13y agoI'd never though I'd say this, but 320x240 may be enough resolution. Especially at 3.5 inches and for hobbyist projects. All the projects I can think of to use this are for simple notification-style display and maybe one finger interaction.
- ama729 13y agoA DIY smartphone seem something where having a good screen would be a plus, or everything photo where color accuracy and resolution are important. I was looking to make an EVF[1] for my DSLR a while ago for example. [1] http://en.wikipedia.org/wiki/Electronic_viewfinder http://en.wikipedia.org/wiki/Electronic_viewfinder
- hahainternet 13y agoI use my Android as an EVF / remote controller for my 550d. It's pretty damn useful and you can pick up a second hand phone for basically nothing.
- ama729 13y agoNever heard of that, that seem interesting, would you happen to have a link with more information?
- hahainternet 13y agohttps://play.google.com/store/apps/details?id=eu.chainfire.dslrcontroller https://play.google.com/store/apps/details?id=eu.chainfire.d... is what I use. USB OTG cable to USB Mini. Does the job fine on a Nexus 5.
- DanBC 13y agohttp://www.mikroe.com/add-on-boards/display/ http://www.mikroe.com/add-on-boards/display/ Mikroelectronika have some interesting displays but they're all little.
- ama729 13y agoCould you point out where are the HD screen? I tried to look, but all of them seem to be 320x240 or lower, which is what I was complaining about :).
- bigiain 13y agoI'm guessing these are all "left over" or superseded feature phone components. I've got a few from a couple of years back that are explicitly sold as "Nokia screens" and all the library code makes it pretty clear they're Nokia 3xxx series phone parts. The "hobbyist LCD" market doesn't get purpose designed components - not at the volumes and prices hobbyists are prepared/capable of buying. We get to re-use end-of-life components or buy the end-of-reel scraps from current product manufacture. (which is fine by me. I love being able to buy accurate 9DOF IMUs, but I sure as hell don't want to order them in reels of 10,000 un-hand-solderable SMD parts)
- baddox 13y agoThe glorious smartphone screens are in smartphones, which cost a lot more than 90 USD.
- ama729 13y agoNot really, the Nokia Lumia 520 for example is at $50/70£, and had an IPS screen with a 480x800 resolution, I never saw such a screen sold for hobbyist. http://en.wikipedia.org/wiki/Nokia_Lumia_520 http://en.wikipedia.org/wiki/Nokia_Lumia_520
- gcb0 13y agothis guy is right. even an overpriced oem replacement for mobiles, with all the extra stuff attached to the board, runs under the $100 range. just paid $98 for a noteII screen and digitizer combo. its full hd i think. so, stop sugar coating. lcd and digitizers are cheap. this is either low volume hobbyist market or pure greedy. and looking at how other things are priced in those sites, like a small roll of wire for $20, id bet it is greedy.
- pjc50 13y agoIt's low volume hobbyist market, obviously. And that has overheads. Don't call people 'greedy' for selling things at greater than the BOM cost.
- drdaeman 13y agoLVDS panels aren't uncommon. In fact, I believe (but not checked) there should be lots of them being sold as replacement parts for notebooks and tablets. For example, relatively recently there was a post on HN about RaspberryPi-based DIY tablet. It had this link for LCD panel: http://www.chalk-elec.com/?page_id=1280#!/~/product/category=3094861&id=14647624 http://www.chalk-elec.com/?page_id=1280#!/~/product/category.... The store page now says it's discontinued, though, but this was meant just as an example and I'm too lazy to search for a better offers, sorry. :) Although, those are probably of no use with AVR microcontrollers directly, without a display controller like http://blog.tkjelectronics.dk/2012/10/lvds-display-controller-for-microprocessors/ http://blog.tkjelectronics.dk/2012/10/lvds-display-controlle... or http://hackaday.com/2009/12/12/fpga-driver-for-psp-screen/ http://hackaday.com/2009/12/12/fpga-driver-for-psp-screen/. Phone LCDs just have it already and panels don't.
- TD-Linux 13y agoCalculate the amount of memory required for a 320x240 256 color display: 320*240 = 76.8KB. An Arduino only has 2KB of RAM, so an external controller has to do basically all of the drawing opereations. This controller has its own SRAM framebuffer. Once you get larger than 640x480, it becomes impractical to have the framebuffer in SRAM. DRAM is the obvious choice, but increases system cost and complexity sharply and so you first see it on "application processors", e.g. Cortex-A7 and up. Also, DRAM PCB routing is very complex, and the connection from the display controller / system-on-chip to display is also critical.
- lgeek 13y agoWell, you'll find the glorious smartphone screens are sold as replacement screens for smartphones. But of course, smartphones tend to have an LCD controller on the SoC, so you just get a raw LCD parallel interface. That means the LCD has a tiny connector with dozens of wires. Hobbyists are often enough scared of soldering SMD parts, they won't try to solder that .4mm pitch connector. Then you realise that even for 800x600 @ 60Hz you need a pixel clock of around 36 MHz, so you probably need a hardware controller, you can't really get away with DMA and/or bit banging. Since you have an external controller, you can't do any of the memory efficient drawing like Nintendo NES or sifteo[0], so you'll need external buffer memory, probably at least 2 MB to fit two (16 bit colour) frames for double buffering. As the resolution grows, pixel clock frequency and memory size requirements grow quite quickly. Soon enough you get limited by the bandwidth between your MCU and controller, by limitations of parallel interfaces and have to switch to LVDS and so on. Most of these issues become much less relevant if a (even small) company wants to design, manufacture and sell something like this. But I'm not sure there's a demand. For most projects a small screen (with a controller chip and available for cheap because it was designed and manufactured at scale for older phones) works well enough (and you can get away with using a wimpy 8 bit MCU). If you need a larger screen, it's probably cheaper to get a low cost single board computer and a computer monitor. Economies of scale and all that. [0] https://www.adafruit.com/blog/2012/12/05/how-we-built-a-super-nintendo-out-of-a-wireless-keyboard-sifteo-sifteo https://www.adafruit.com/blog/2012/12/05/how-we-built-a-supe...
- ama729 13y agoThanks for the explanation. That's something I wondered, taking a smartphone screen, but it seem pretty daunting, indeed. Such a shame in a way.