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DLT one - A Damn Linux Tablet!

Modular Open Source Hardware Tablet that is easy to hack and can run a standard Desktop Linux Distribution (or Android)

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Proper Linux Tablets unfortunately just dont exist and certainly not ones that are also open hardware.
I want hardware that does not lock me into a specific OS or cripples other options by the lack of drivers. I'm also sick of the lack of modularity and repairability of modern hardware.
So I will create the following.

A basic system for a modern and highly performant portable device (e.g. Tablet) in the 7-10" form factor.

The electrical and mechanical design will allow for a multitude of form factors in the future, basing on a shared approach on how to interconnect hardware, so reuse between form factors will be possible.

These newly developed standards for modular portable devices will be open to everyone and the same goes for the design of the Tablet that is being developed here.

For more details please read my project logs and the detailed description below.
The development started with the HaD Prize 2019 and you will be able to follow every step of it.

How it addresses the Hackaday Prize:

Current mobile hardware is very closed and monolithic. Making repairs really hard and modifications or upgrades impossible. I want this to change as I don't think this is very sustainable and keeps smaller companies and users out of the market.

I want to create a highly modular, upgradable and modifiable tablet and with that also a standard for open mobile computing where you need to think about new concepts for modularity as the old standard from PCs and Laptops don't really work anymore.

I want to enable more companies and enthusiasts to create their own niche products without the need to re-invent the wheel every time and re-use the work from others.

This will be achieved by defining a mechanical standard for creating cases and an electrical standard that defines interconnects, pinouts and behaviour. This should enable the re-use of peripherals through different motherboards, housing different SoC's, from all kinds of performance spectrums and keeping the cost of replacement and repair down to a minimum and enabling very quick development of new features/peripherals for the ecosystem.

Some project logs going into details:

https://hackaday.io/project/164845/log/166748-mounting-plate-mock-up

https://hackaday.io/project/164845/log/167049-peripheral-bezels

https://hackaday.io/project/164845/log/165497-manufacturing-and-the-target-audience

https://hackaday.io/project/164845/log/163897-mechanical-design


Motivation:

For years I've been wanting to create a tablet like device based on a SoM (System on Module). Doing something from scratch, routing DDR3 RAM, eMMC etc. didn't seem realistic to me, this is not only really hard but also very expensive. So SoM it is, which comes with the additional benefit of user upgradability if the SoM manufacturer stays true to their pinout with successor products, which they usually do if the SoM is in any way meant for an industrial market.

Back then I started out with the Raspberry Pi compute module but the more I thought about my specs the clearer it was to me that it just wont cut it.
I wanted something that can run modern applications, something that is actually very usable and is not just a cool thing on paper.

The past years I've been looking around for affordable SoMs that offer enough performance to be viable, until now there were either cheap outdated SoMs or ones that mainly target the industrial market and are too expensive.
In recent months there is finally an interesting selection of SoMs out there.

Technexion/Wandboard released the Pico SoM product range and the Pico Pi as a dev board. They range from 72-150$ For 150$ you get a fairly decent ARM SoC with 4K video support, 4GB RAM, 16GB eMMC and 802.11 AC WIFI and Bluetooth 5.0.

Essentially the basic specs for a modern tablet.

The other SoM that just popped up recently is the Nvidia Jetson Nano. Very capable SoM with similar specs but lacking WIFI. Though the GPU is much more high-end than the iMX8M Quad.

Another very important part is the Display. Until now I never found a satisfying product that had a good picture quality and resolution. It just feels wrong to use a 800x480 display in 2019.

For some reasons there are really great IPS displays popping up all over the place from 1.8" to 13" there is something in every category and all of them can be considered to be "retina" displays. If I want to make a tablet I don't want it to feel like tech from 10 years ago.

So the goal is to make it good or go home :)

What this project will then essentially entail is to design a carrier board for one the two SoMs (though I want to see if I can keep it generic enough to allow for different SoMs in the future) and create a mechanical design that will fuse display and carrier in a visually pleasing way while maintaining the goal of hardware modularity end reusability.

... Read more »

  • Roadmap

    Prof. Fartsparkle2 days ago 0 comments

    I want to quickly outline what I want to do in the coming months and what milestone I want to reach.

    Given the news that I made into the Hackaday Prize Finals I will have to speed up some of the development as I feel the current state is not yet conveying my intentions well enough.

    What I will try to do in the next 2.5 weeks:

    • Finish design of mounting plate and have it milled or laser cut in aluminium.
    • Model the plastic piece that comes between display and mounting plate. This is quite important for aesthetics. This will have to be 3D printed, either in SLS or SLA.
    • Finish 2 more face plates so the most important peripherals can be broken out, I will print and possibly paint these myself as that is very doable on the Form 2 that I have access to.
    • Design a back plate and have it printed or milled. Preferably also a monolithic back plate but maybe I 3D print that on the FDM, this is mostly to show that both is possible, monolithic and modular design.

    This is a lot to do for this short amount of time and I'm not sure I will get it all done in time but I will try.

    Next up would be finally rev. 3 of the motherboard. This will have the reverse mounted module, which would technically allow the first fully self contained prototype. Given I also make a basic li-ion charger module but if I don't go with USB-PD in these first tests this is very straight forward.

  • Feeling a bit stuck

    Prof. Fartsparkle2 days ago 0 comments

    I haven't been very productive in the past few weeks. This was mostly due to me being a bit frozen with my eDP issues. I'm hesitant to move forward with the PCB design before this issue isn't fully understood.

    Getting the display to work is quite important to me and right now I'm not able to debug why the seemingly same circuit, layed out with the same guidelines I used previously is giving me these issues. At the moment I'm reliant on Nvidia's support as I have no real starting point for debugging the issue atm. The pace picked up a bit on their side and after a few weeks of silence the hardware team on their side couldn't identify any real issues. The software team on the other hand found some odd behaviour in the link training. Link training is a feature of DisplayPort that consists of finding out the correct signaling strength and receiving display timing data from the display (similar to the EDID readout step in HDMI).

    When it tries to establish a link the SoC does not try to up the voltage swing of all signal pairs but only for the first one. So most signal pairs stay at the lowest setting of 400mV, the first goes up to the maximum of 1200mV. This can mean two things, either there is a bug and because it does not raise the voltage swing for the other signal pairs it just fails over and over because it only touches the first pair. The other possibility is that everything is great with the other pairs at 400mV but something is very wrong with how the first pair is routed and the attempt of the driver to fix it fails, which atm seems unlikely but who knows.

    What is so frustrating about this is that I know what to do next and have a pretty good plan to bring this project to where I want to see it but I'm held back by this odd ball issue and I can't do much about it.

    I'm focusing on the mechanical side for now which can mostly be handled without advancing on the PCB design. I might still start with the newer PCB design as the production module for the Jetson Nano SoM is finally available which I had to wait for because the pin out changed there in relation to the pre-production devkit module. This new revision will feature the much needed reverse mount to the aluminium mounting plate which means I can finally get rid of this big silly heatsink.

    In the next post I want to outline quickly what step I want to take in the next months to give you an overview of the development roadmap that I have planned so far.

    On the bright side, I came around testing the fixed USB PCBs and all is well now :)

    Here it is happily talking to an Adafruit Metro M0.

  • Peripheral Bezels

    Prof. Fartsparkle08/13/2019 at 21:58 3 comments

    These are a solution to the fully customizable tablet version. If you read the project log about manufacturing I talked about having two different back cover plates essentially. One that is monolithic and neat, only usable for a fixed pre-selected set of peripherals.
    The other would be the hacker, maker, researcher option that lets you fully customize position and amount (and kind) of peripherals, making it also easy to add you own custom hardware.

    The issue I had to tackle was how do you achieve this without having open sides or requiring 3D printing from the customer.

    This is the solution I came up with (pictures below). Each peripheral will have to choose a bezel size. I haven't decided how many I want to include in the mechanical standard yet but it will probably be around 2 size options. They will only be allowed to differ in width, not height. Height is fixed for every element.

    To close of the space between peripherals we have spacer blocks, they come in the same widths as the bezels, so if you have give amount of spacer blocks you can always make a closed side surface, even if you add your own peripheral, all it has to do is adhere to this mechanical standard.

    The raster length is always a multiple of largest block width. The corners help define this, without them you will run into issues with different screen sizes, so the corners will always extend into each side of the tablet until they form this fixed raster length. That way you can adapt this to any screen size up to a certain minimum size given by the block width.

    Finally some pictures of the prototype prints that I made for illustration. This will of course look much much nicer with injection moulded pieces and an aluminium mounting plate instead of clear acrylic :)

  • Mounting plate mock-up

    Prof. Fartsparkle08/07/2019 at 22:14 2 comments

    I made a rendering of this before but I now laser cut a mock-up out of acrylic (the real deal will be aluminium).

    It's purpose is mostly to test out how well the positioning of the peripheral works out and to experience any issues when working with a real display and PCBs. It's also the first illustration of the whole modular peripherals idea.

    The result was quite promising. I also realized that I could slim down the thickness of the shim layer which raises the mounting plate high enough so it can sit just above or on the back of the LCD. I had concerns because there is always a part of the LCD that is thicker than the rest where the connector comes out (usually all covered up with black tape). I can just leave a cut-out there as the touch screen offers enough supporting area and lower the overall height of the shim. Here a picture of the whole mock-up assembly.


    Placing the peripherals worked pretty well! The hole raster on the edge (and to a degree in the middle) is all threaded 2.5MM holes in a 5mm pitch. This gives nice even distances of 5mm increments for both positioning as well as hole placement on the peripheral PCBs.

    Here a few close ups of some peripherals

    It is crucial that pure SMT components are used for this. With hybrid components like this HDMI connector below, you need spacers to raise them enough, those spacers are a bit too much but still, it will always add a 1-2mm to the overall thickness of the assembly.

    This hopefully illustrate how the whole modular peripheral concept is supposed to work. This is of course an early stage but it shows where it is supposed to go.
    As you can see there is always a slight offset from the edge for each PCB. This space is intended for the faceplate that each connector will receive and will make for closed side surface, even with a modularized back instead of a pretty but fixed injection moulded back.

    I will print mock-ups of these face plates in the coming week. So the next update is hopefully showing those off.

  • Problems with revision 2

    Prof. Fartsparkle08/07/2019 at 21:58 0 comments

    Unfortunately the new revision had quite a few issues that I was not expecting. Revision 2 was largely a form-factor change, the circuitry was tested with the SBC style PCB in the first revision.

    So what changed? Mostly that peripheral and most of the circuitry went on their own little PCBs and are connected via FFC to the mainboard which now has a much more reduced circuitry, that brings costs down for the mainboard and you only pay for the peripherals that you actually need, this also enabled a free positioning of the peripherals but more on that in the next update.

    Back to the mainboard. When I powered it on with Ethernet attached I got no device showing up in the network unfortunately. When I attached the serial console I got at least a boot log so things were actually running but it seemed kind of flaky, I often didn't get a login prompt at the end of the boot process. At the time I was thinking I was having power issues but in retrospect I think this was just a bug in an older version of JetPack (the OS for the Jetson, a modified Ubuntu).

    I turned to the schematics and realised that the pinout on the Ethernet FFC connector was shifted by one pin to the right...
    The same happened to the USB which I tried next with an Ethernet dongle but had not luck either for the same reason, pins were offset.

    I was really puzzled about how that happened until I realised that the tabs of the connector which carry no signal were on the same side as the actual data pins on the schematic. When I mirrored the pinout I just mirrored it and applied it to the connector again in reverse order. The issue was that I included the tabs in that process and assigned them a signal instead of the GND connection...


    Oh well, fortunately not the most important peripherals for now and I learned a (circuit) life lesson.

    The eDP and HDMI connector pinout were fortunately all good, I took a bit more time on those and didn't rush them out in day like the other peripherals.
    Unfortunately they didn't work either. At that point it got quite frustrating, I went from a 100% working revision to a 10% working revision.

    I quadruple checked everything, first thing I found was that I missed the eDP hot plug signal, it got renamed in the whole moving process. This was quickly fixed with a bodge wire. At that point the Jetson tried to establish a connection with the display and did seem to communicate but always failed during the link training process which establishes certain ground rules with the display for how the connection will be handled. The equivalent to this in HDMI is the EDID readout with the addition here that there is also some negotiation about the amount of signal lanes to use and other timing related things.

    I did not get any further with this unfortunately. I tried wrapping my FFC cable in copper foil to shield it. I used shorter DisplayPort cables. Nothing worked. I got contacted by a person from Nvidia that also already helped me before with design resources, so hopefully I will get some more insight there of what might be wrong. Again, the circuit did not change, its all the same.

    HDMI was a similar situation, EDID read fails but fortunately the Jetson goes into a default resolution for the HDMI for some reason if it can't read the EDID and this gave me a picture! So that at least hints that its not an impedance issue introduced with the FFC cables.

    Why does the EDID read fail? I do not know, I checked the circuitry surrounding the I2C signal level translation but could not find any issues introduced with the move.

    It is interesting though that both fail at a similar stage, the EDID readout / link training.

    I tried the actual eDP PCB which connects to the eDP panel instead of a DisplayPort display. Unfortunately no difference, here I get even a stranger behaviour, the Jetson does not boot at all. When I unplug it and reset it is booting fine again. Hot-pluging it 'works' it atleast doesn't crash the system and yields similar edid / link training error messages as with...

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  • Revision 2

    Prof. Fartsparkle08/07/2019 at 21:25 0 comments

    I've been busy the past few weeks.
    I held back a bit with this update as I wanted to get certain things finished and some things debugged first (which wasn't successful yet).

    You could follow along with my daily struggles on twitter if you are interested in more regular updates. I use this blog more for the condensed version every couple weeks.


    The boards arrived a while ago from JLC, again in matte black which now comes at no extra cost which is quite nice! I know PCB business cards are a bit dated by now but you could get them now in glorious matte black for 2$ which is just insane...

    They were also supportive and sponsored a large part of the order which I think was the largest PCB order, in terms of different designs, that I've ever done...

    Here a shot of all of them together.

    I got to populating the mainboard first, here a few shots of before and after reflow.

    Got quite a few shorts which was annoying but nothing that the soldering iron couldn't fix.

    Except for this little fellow which gave me quite a headache before I discovered it. It was shorting 1.8V with 3.3V...

    And another shot of an HDMI peripheral board as well as Ethernet (not really considering Ethernet for a final version but its great for debugging)

    So how did it go you may ask? Not very well unfortunately. More on that in the next post (which will come out in just a few minutes)

  • Manufacturing and the target audience

    Prof. Fartsparkle07/08/2019 at 23:17 4 comments

    A topic I haven't talked about in too much detail yet.

    Its something I'm constantly thinking about whenever I change something in the design. The tricky part is that I want to reach two main target audiences which require somewhat conflicting mechanical design.

    The first one being the general open source crowd, no matter if they are interested in hardware or not, there is quite a lot of interest from people who are interested in Linux and open development. They mostly want to see a tablet that comes close to a polished commercial tablet, from the feedback I've got it seems they are fine with something thicker but it didn't seem there was a ton of interest in fiddling with hardware or getting something that works but looks ugly. Small to mid sized industrial companies are also pretty interested in something like this, they would require a more rugged case and are also fine with thickness but also require a finished and polished product that is well integrated.

    Catering to this crowd is actually not hard, you require a few injection moulded pieces of plastic (I try to keep it as simple as possible, so far I see about 2-3 large pieces of plastic) and make a design that is constrained and tries to squeeze the hardware into any space there is to yield a tablet that looks nice and tidy, just as a tablet would look like that you bought from the usual Manufacturers. Sure there will be a few iterations until it comes out perfect but injection moulding is a well understand process and can be done in any quantity now a days. There is polyurethane casting for prototyping and small runs of 10-100pcs.

    Next step would be injection moulding with an aluminium tool, they are a lot cheaper to manufacture than the high-end steel ones and yield y few hundred to maybe 1k pieces and if you are going really big you can scale up to steel tools and produce several 10k-100k per tool ( I pulled those numbers out of my nose but this is the range I remember).

    The issue is that I can't design the mechanical parts so that they are only feasibly manufacturable with injection moulding.

    This is because I have a second target audience that I personally find most exiting and is what drives me personally. It's the hardware hacker crowd, the educational crowd, the mid-size company that wants 10 super specialized tablets that integrates their own weird oddball hardware.
    Those people want to modify the hardware, they want to experiment, they want to make their own spin-off.

    For this audience I need to think about hack-ability. It doesn't mean they don't want a somewhat good looking tablet, but extendability is key here.

    This is one reason why I design the electronics in a very modular way, no peripheral is fixed, everything is changeable. Don't need HDMI output? Then don't get the HDMI PCB. Need it 2 years later? Just buy it for a small amount and add it to your tablet, no need to buy a whole new thing. This not only allows upgrading to some degree, it also allows for great repairability which is something pretty much everyone likes.

    Now there is a catch here, how do I add an HDMI port to a case that doesn't have an opening for it?
    This why I decided to design the case in the following way. There will be a display assembly that consists of LCD, Touchscreen (the two will not be bonded for repairability) and a plastic 'spacer' that creates a frame around the LCD. This assembly is then acting as a flat surface where the aluminium plate will be attached to.

    This plate will have a sort of pegboard pattern of 2.5mm threaded holes where the electronics can be attached to, this allows for free placement of all peripherals and the motherboard. This plate can be easily manufactured in lots of different processes, its thin enough to be done in a sheet metal process, using water-jets or lasers, or more expensively, on a milling machine.

    The tapping will be a bit more expensive than just having threads in a limited amount of places for a fixed set of peripherals but this...

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  • LCD and Touchscreen combo

    Prof. Fartsparkle07/07/2019 at 20:46 0 comments

    I got a nice 8.9" eDP LCD and a fitting touchscreen with a glass cover in typical tablet style, they only got white in stock, I would prefer black for future tests but it works well for first tests. Touchscreen was working perfectly in Ubuntu out of the box.

  • Revision 2 ordered

    Prof. Fartsparkle07/07/2019 at 20:34 0 comments

    It's been quite a while since the last update. Some private events kept me busy for a few weeks and I had somewhat of a slump, the second prototype was all about defining sensible pinouts for all the FFC's, finding out what connectors to use, what pin counts, what problems could arise in different applications than mine with the pinout I'm choosing and lots of other little decisions.

    It's important work but can feel a bit like a drag because you essentially just redo what you already did in a different way.

    I've worked through the slump and churned out a new motherboard and over the weekend I made 7 little peripheral breakouts.

    This will be the first proper proof of concept. The part I'm most anxious about is the eDP to LCD part, I've never talked to eDP LCD directly before, so lots of stuff I could have missed.

    Now that I'm waiting probably about 2 weeks for all those boards to arrive I will focus on milling a prototype aluminium frame to attach these PCBs to. I also got a nice LCD and touchscreen from a vendor, more about that in the next post.

  • Found all the bugs, working on next design

    Prof. Fartsparkle06/12/2019 at 21:17 1 comment

    So turns out I simply forgot to connect the AUX_GND pin for the DisplayPort connector, a quick bodge wire and DisplayPort was working as well :)

    Ethernet is only 100Mbits because I mixed up the connector pinout. Molex had two versions for the part that I used and for some reason the bi-color MagJack has a different pinout for the diff. pairs rendering 2 pairs useless which makes me end up with just a 100Mbit connection.

    I have ordered the correct part for the pinout and will see if it works ok after reworking it.

    I'm currently in the process of designing the next prototype which will be the actual first prototype meant for the tablet instead of a SBC like before.
    It will be as compact as possible and breakout everything over FFC like I planed. This also means I have to spec the electrical standards for each peripheral. This will probably not be final but its important to keep future solutions in mind here already. After all its supposed to be a universal standard for portables, not just for my initial tablet here.

    I expect this to take another 2-3 weeks as I wont have too much time due to private life stuff.

    But I want to see it assembled in mid July and maybe do a second revision before the judging deadline in late August.

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chris wrote 05/30/2019 at 08:44 point

This is way cool. I'm been so desirous for a full blown Linux Tablet, something in the hardware realm of the Microsoft Surface Pro. My needs are a bit more high end (lots of RAM ~ 32GB, and at least 1TB disk) as I'm running lots of VM's. Need something that can replace my laptop and iPad\Android Tablets...one device to do it all that runs Linux Proper (not WinBLOWS).


Best of luck with this...

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Daniel Dunn wrote 04/12/2019 at 01:54 point

Awesome project! And it's a chance to fix the big mistake that 99% of portable devices seem to have. 4.2V is too high for batteries and it wears them out twice as fast as slightly less charge would!.   I think it would be cool to use 1 or 2 18650 batteries for something like this, because it's so easy to find them.

A Linux tablet would be great because Android is really restrictive about hardware access and it makes mesh networks way harder than they should be.

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Prof. Fartsparkle wrote 04/12/2019 at 20:07 point

Haven't decided on a battery system yet but I will probably utilize a smarter IC for that which should offer settings for these kind of things which should be settable from the SoC.
I might even put it on its dedicated PCB so you can choose battery chemistry and charging circuitry yourself without spinning your own baseboard flavor.

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mbt28 wrote 04/09/2019 at 11:40 point

Hi, 

I think you should go for a sbc which fits with your design. You may go for edged sbcs too. 

Routing hdmi, usb 3, pciexp and mipi is quite hard actually. 

For the lcd side, I highly suggest to use an lcd with an available documentation and driver support. I think this is the case for you, otherwise it consumes so much time to adapt a bare mipi dsi lcd. 

My last comment is do lots of research about the base board you will use. I highly suggest you to dont use chinese boards because they lack of support which will take most of your time. 

Gl&Hf

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Prof. Fartsparkle wrote 04/09/2019 at 21:25 point

Hi,

thank you for your comments.
Using a SBC is not really an option if you want to make a thin device with modular peripherals :)
Like I wrote in my description I will either use the i.MX8M SOMs from Technexion or the Nvidia Jetson Nano SOM. The i.MX8M SOMs have a detailed datasheet available and NXP offers an insane amount of support material for their SoCs. Which is why I will very likely go with the i.MX8M. The Jetson Nano might still be nice but so far there is no documentation and I would like to get started soon.

I do know that routing high-speed buses is more work than fanning out a few GPIOs :)
Though I want to take on that challenge. I've touched that topic on older projects and feel confident that I can make this work.
I worked with MIPI displays before and the bus is surprisingly robust, I could run full hd displays on a meter long FFC cable which technically violates the MIPI specs quite a bit but the displays didn't care one bit.

About hardware from China, I will source the displays from china but mostly because they are sold there. I found some panel from Sharp and got a datsheet for it. I hope I can modify an existing driver for a different Sharp panel and adjust the code for the start up sequence according to the datasheet.

If you got some experience there I would glady here about it :)

But yes, I will not buy random unknown crap. I want to end up with something that is manufacturable and will only look into hardware that is well documented and has a manufacturer behind it that offers support.

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mbt28 wrote 04/10/2019 at 09:04 point

Hi 

I was talking about something like this when I was saying about edge sbc:

https://www.khadas.com/shop

In this way you dont have route hdmi usb etc. 

I.mx8m is amazing soc. Has good support and very capable. I like imx8m mini more since I dont need a hdmi. 

Nxp chips are so good but unfortunately they are expensive when you want to buy single quantity.

You might go for rpi compute module but I am quite sure adapting mipi dsi to an existibg lcd would be quite hard. 

My 50 cent is do your work part by part for example you can go for an sbc and design the lcd interface, audio etc. Then, when everything is okay you can adapt them to the som version. Otherwise debugging the hardware is so much time consuming. 

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Prof. Fartsparkle wrote 04/10/2019 at 11:53 point

@mbt28 that "Edge" board is super interesting. Thank you for that I will definitely have a look at that :)

It does not really fit in my overall goal of modularity and being somewhat SOM agnostic but if I end up in a dead corner I will give this a go.

Anything RPi based is a no go, they are just too slow. This is what I experimented years ago and just ended up not pursuing it further because it can't keep up with modern applications performance demands.

The workflow you suggest is what I'm doing. I have now a dev kit from the SOM manufacturer which is a full SBC and comes with a MIPI DSI touch screen.

So I have a working base there that I will start to adapt from slowly. I will work with this known to work screen for now and if I got a very basic system going I will see if I can make other screens work that may not have a public driver available yet.

I do PCB and Software design as a day job so I do bring some experience with me to hopefully not fail miserably with all of this :)

If you know a good source for existing MIPI drivers outside the mainline kernel I would much appreciate that :)

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mbt28 wrote 04/10/2019 at 12:22 point

Hi,

I always find MIPI DSI a bit complicated. I am using lvds screens, those are more straightforward. 

If you want to go for LVDS ones, there are DSI to LVDS bridges by Texas Instrument called sn65dsi8*. They are easy to use. If you want to manufacture it by hand, bga package is cheaper and beleive me is easier to solder by hot air gun or owen.

You can configure it through I2C and there is even an application called DSI tuner you can configure the chip and create a script for it.

http://www.ti.com/interface/hdmi-dvi-dp-mipi/bridges-transceivers/products.html#p1694=Bridge

http://www.ti.com/tool/DSI-TUNER

And there are some useful information on this website (LCD interfaces, backlights etc):

http://www.programmersought.com/article/7481201221/;jsessionid=F29EEE6C46D8DE26C33BF8BE08D5C924

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Prof. Fartsparkle wrote 04/10/2019 at 13:21 point

@mbt28 those bridge ICs are something I also looked into, at least for HDMI. LVDS sounds like an interesting option. Valuable to hear that they were easy to deal with from your experience.

What makes LVDS easier in your opinion? I don't really have experience with it.

Thanks for all these resources, that is very helpful!

I will have to see if there are LCDs with LVDS available that are high-res enough. I wanted at least Full HD or "2k" for anything larger than 6". It makes life harder but its something I don't want to compromise on.

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mbt28 wrote 04/10/2019 at 13:35 point

"What makes LVDS easier in your opinion?"

DSI is a bileteral communication. Some LCD's need to be configured via DSI as well. I am not familiar with it, and usually hard to find detailed  datasheets for dsi panels. Maybe because of NDA aggrements, I dont know actually.

LVDS is just serilization of RGB interface with 4 data pairs and one clock lane. It is one direction. Usually you need to configure some functions of LCD via GPIO, which is pretty easy.

Another issue with DSI; it has higher speed so routing it is a bit harder than LVDS.

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Asher Gomez wrote 04/09/2019 at 00:23 point

Nice project, I'd definitely want one of these... Good Luck!

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Prof. Fartsparkle wrote 04/24/2019 at 11:38 point

thanks :)

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