Nextion, RA8875/6, EVE2, FT81x intelligent displays? - Page 1
Forum section: electronics / projects

author: Martinn
author_rank: Frequent Contributor
timestamp: November 15, 2020, 05:19:34 pm
content: Hi,I am currently working on a power feed controller for my milling machine, based on a STM32F429https://www.st.com/en/evaluation-tools/32f429idiscovery.html2.4" QVGA discovery board.As features accumulate, I am running out of display space:so I'd like to add a larger (like 7") display. Although the F429 has an LCD controller, I'd rather not mess with that but add an external display, which then has to be of the "intelligent" SPI or other kind. In the title I already listed the choices I am aware of:NextionRA8875/6EVE2Bridgetek FT81xIf I keep the contents as in the existing screen layout, I just need text write functions with HUGE fonts for coordinate display. Preferably double-buffered to prevent flickering. Maybe some icons and fixed graphics on top, not much more. No touchscreen (workshop use - oil and metal chips).Can anyone recommend which controller type to look for? I a looking for an easy to use interface, cost is not that important as it is just this one piece. More important is to have a solid base for future projects.And while I'm at it: I have seen my share of super-crappy Chinese LCDs. Are there still large differences (contrast, color, viewing angle) in this class?Thanks! Martin

author: coromonadalix
author_rank: Super Contributor
timestamp: November 16, 2020, 05:11:17 am
content: the best thing would be to find a bigger screen with the same chipset if there is, so the coding would be simplified and corrected to the newest screen size ...https://www.alibaba.com/product-detail/3-2-inch-TFT-LCD-Touch_60441054477.html?spm=a2700.galleryofferlist.normal_offer.d_title.503b3318D9hmLnhttps://www.alibaba.com/product-detail/4-3-Inch-480-X-272_60231352857.html?spm=a2700.galleryofferlist.normal_offer.d_title.1e393318AViaTebut you're still limitted to 320x240 pixels of definition of th ili9341 lcd chipset driver

author: coromonadalix
author_rank: Super Contributor
timestamp: November 16, 2020, 05:46:43 am
content: some infoshttps://www.pjrc.com/store/display_ili9341_touch.html

author: Martinn
author_rank: Frequent Contributor
timestamp: November 16, 2020, 06:16:15 pm
content: I hadn't thought of keeping the existing LCD interface... nice idea though. Doesn't get me to 7" unfortunately. Also wiring (unless the connector would be identical) could be a thing.Regarding Nextion, I researched a bit and found "reverse engineering font format", "experimental font editor"... so custom or large fonts does not seem to be their thing.Bridgetek (former FTDI) EVE3https://brtchip.com/bt81x/has large fonts built in and has a font converter utility that lets you generate up to 255 pixel high fonts. Not HUGE, but maybe good enough.Matrix orbital sells displays with EVE3, like thishttps://www.matrixorbital.com/ftdi-eve/eve-bt815-bt816/eve3-70g?sort=pd.name&order=ASC7" one.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: November 17, 2020, 08:15:44 am
content: For a single unit I would consider going to an R-Pi zero driving HDMI out to a 7 or 10 inch hdmi lcd. Easy development under linux with whatever font and language you want.communicate to a micro for any real time control you need.

author: djerickson
author_rank: Regular Contributor
timestamp: November 17, 2020, 11:41:43 am
content: I've been using Nextion for a few months now. So far 3.5" screens with AVR Arduinos. Price is $35, contrast is good, not great. Touch screen works well. Their GUI editor and simulator tool works really well.Nextion has up to 256 pixel fonts. Their 7" screen is about $100. Super simple to connect: 4 wires for power and a serial port.I had trouble with their Arduino libraries, so instead I use the simplerhttps://seithan.com/Easy-Nextion-Library/Good luck!Dave

author: Martinn
author_rank: Frequent Contributor
timestamp: November 17, 2020, 06:06:45 pm
content: Quote from: chickenHeadKnob on November 17, 2020, 08:15:44 amI briefly thought about that too. I have a zero w here - I'd run python/pygame, which is already installed and does double buffering.Main problem: It takes ages for this thing to boot. Maybe a minute. 2 s would be nice, 5 s still acceptable. There are many articles on this topic, it seems that achieving < 10 s is really hardcore - which I don't want.Quote from: djerickson on November 17, 2020, 11:41:43 amDave, do you have a reference - like a manual - describing this? When I checked, the font handling was not too convincing. Maybe I haven't found the right documentation.BTW the EVEx chips also have a very simple (SPI) display. The problem with this discovery module is that there is so much stuff crammed in that there are barely any pins free.Cost-wise, 7" is arount $100 either way, seems to be dominated by the panel.

author: djerickson
author_rank: Regular Contributor
timestamp: November 18, 2020, 09:08:28 pm
content: Martinn,I just opened the Nextion Editor and the Font Generator. There are a few hundred fonts and they all have 16 to 254 pixel sizes.Dave E.

author: Martinn
author_rank: Frequent Contributor
timestamp: November 22, 2020, 07:20:04 pm
content: In the meantime, I ordered an EVE3 display from Matrix Orbital:https://www.matrixorbital.com/eve3-70gDisplay quality is OK, not stellar.The EVE controllers definitely take some time getting used to, but after half a day I had Rudolphs example with his library runninghttps://github.com/RudolphRiedel/FT800-FT813If you speak German, I highly recommend reading the original mikrocontroller.net article (link in the github page at the bottom). The Eve chips are rather special - programming is a bit cryptic, but there are excellent tools (and many hints in the bridgetek forum) available so in the end, they are quite fun to work with.There is one serious (not obvious) drawback however: Instead of having a screen buffer where you can indefinitely add stuff, there is a list of objects which is then displayed by the controller. This list is somehow limited and if it's full... it's full - end of story. So this limits how many graphical elements you can add to the display. My example here occupies 29% of the display list already. I guess for my application it's OK, but you could definitely not draw 384000 individual pixels while calculating a mandelbrot set (or even a few scope plots).