Topic: Compatible display

I have a used Samsung LTN184KT01-101 display (datasheet: http://www.jxlcd.com/Upload/PicFiles/LTN184KT01-101.pdf ), and I am wondering, whether it is possible to connect it to a Novena?
What would be needed?
If it is not possible, is there a display that can be bought and connected to Novena directly?

2 (edited by gavwhela 2015-03-30 08:31:43)

Re: Compatible display

I'm not an expert on the hardware needed, but I believe it should be possible. The iMX6 platform has support for driving LVDS which is what that display uses. For the desktop version the display uses a eDP connector, so it comes with an adaptor board from the LVDS connector on the novena mainboard. To be sure what you'll need to have your display work you'll need to examine more about the novena LVDS connector and the display's connector, in order to see how compatable they are. From the notes in the PVT2 circuit diagrams (page 13) it sounds like you'll need a custom cable, it also says that it's designed to work with LED backlit displays, so you may need to do extra work to have an non-LED display work.

Re: Compatible display

You will have to build or acquire an inverter  to drive the backlight on that display.  Page 12 of the specs describes the characteristics required.

Re: Compatible display

Not only could you drive that display, you can drive TWO of those displays.  The port that goes to the eDP board has two LVDS channels.  In the desktop and laptop models these channels go to a board that gangs the two channels together as one and converts the signal to eDP, but everything is set up to allow you to drive two independent displays.

There's a PWM channel on the ribbon cable, too, which you'd send to a backlight inverter such as what GregRob mentioned.

There really needs to be a way to design and fab cheap on-demand boards for this sort of thing.  Have a template project that you can clone, modify a bit, and send off to e.g. dirtypcb for ten bucks.

Re: Compatible display

I have a seperate small board that likely is an inverter. I guess I will figure out how to drive the backlight myself.

But I think I need help for designing such a board to interface LVDS, so if anyone could help me design such a board, I could create a generator for it. Is it just necessary to have 2 connectors on the board and to connect the pads, or are some passives/actives needed as well?

Re: Compatible display

You'll want to break out the PWM and power supplies used for the backlight, and send those lines out to your inverter.  You can do something clever with the USB port and/or resistive touchscreen wires that are on that port, too smile

But it should be a straight passthru.  If you're going through all the trouble to design a board, you might as well break out both of the LVDS channels while you're at it.  Get two displays for the price of one.

Re: Compatible display

I've actually laid out a basic board for this and passed the files on to Sourcerer. I've also ordered myself up a few from dirtypcbs, and the connectors from RS - I may have a few spare, if it actually works. However, I haven't found a source of the 54-pin FPC cable, nor the novena-specific fancier version bunnie produced. Anyone have any suggestions where I could obtain such a thing? (I'm MadHacker on IRC, BTW)

8 (edited by projectgus 2015-04-06 18:33:58)

Re: Compatible display

Hi James,

james_a_craig wrote:

I've actually laid out a basic board for this

Neat! Any chance you posted it online as well?

james_a_craig wrote:

However, I haven't found a source of the 54-pin FPC cable, nor the novena-specific fancier version bunnie produced. Anyone have any suggestions where I could obtain such a thing? (I'm MadHacker on IRC, BTW)

For "Novepad" I used cheap & generic 50 pin 0.5mm FFC (the end 4 pins are only used for resistive touch, so you can offset a 50 pin cable into the 54 pin connector). Pic here. Using a 80mm long cable seemed to introduce a bit of noise but shorter might be OK (although that was at 165MHz also, clock speed should be lower for this display so 80mm long might be fine).

I'm also interested in maybe doing a group order for the custom FPC. itead and some of the other cheap PCB services will do it, but it's still reasonably expensive. I think when I last looked it was about $100US for qty 10. Let me know if you're interested too, and I'll start another thread about ordering some.

Angus

Re: Compatible display

I am interested in 3 FPC cables.
Is it perhaps possible to buy even wider cables, e.g. 60 pins wide that we could cut off after 54 pins?

Re: Compatible display

projectgus wrote:

Neat! Any chance you posted it online as well?

Not yet. I'll consider it once I actually get the boards back and see if they work worth a damn. I'll probably redo the layout a bit before I post anywhere else, simply because I think my layout is a bit crap - I was in a bit of a hurry. Once I'm a little less busy I'll do a better quality layout and tidy up the silk-screen better etc. so it's something I'm happy having my name associated with.

projectgus wrote:

I'm also interested in maybe doing a group order for the custom FPC. itead and some of the other cheap PCB services will do it, but it's still reasonably expensive. I think when I last looked it was about $100US for qty 10. Let me know if you're interested too, and I'll start another thread about ordering some.

I've just found that toby.co.uk - http://www.toby.co.uk/content/catalogue … xx-A-xx-xx - carry the 54-pin FFC cable, albeit in odd lengths.

Re: Compatible display

I've realised that my original board done in DipTrace had a pretty serious mistake, at least for my purposes - I'd used 0.1" header instead of 2mm, and the standard cables for these displays, widely available off eBay, use 2mm headers. Since I was going to have to redraw it anyway, I've redone this layout in Eagle (which does a better job of differential traces anyway) and uploaded it here:

http://www.jamiecraig.com/lvdsadapter.zip

I have literally no idea if this board works - in fact, after my last screw-up on the board layout, I imagine it's a safe bet it doesn't! - but if anyone wants a look or to use it as a basis for their own boards or whatever, go right ahead.

Caveat emptor.

PS. I rather doubt that the USB header will work well, since the impedance of the PCB will be well off what the USB spec requires for USB 2.0 - it's tricky to get this right on 1.6mm 2-layer board when you have the signal coming from tiny narrow connectors too. I'm sure someone will be able to do a better job of this than me, but it's a start.

Re: Compatible display

I bought some 54-pin FFC cables, which I received now, and I have a few left. If anyone needs some, let me know.

Re: Compatible display

I'd be interested in 1 cable.

To my understanding, we have:
2 LVDS chanels
1 pwm signal
1 line to drive one res. touchscreen
1 USB line

If I use an old Thinkpad lit with these little LED on top of it, could the USB port be missused for that?? (I remember an old trick to sent a datastream to /dev/null over the serial port to light an LED..).

2 LVDS channels, hmmm doublescreen labtop....

14 (edited by dbtayl 2015-08-24 10:37:46)

Re: Compatible display

mclien wrote:

If I use an old Thinkpad lit with these little LED on top of it, could the USB port be missused for that?? (I remember an old trick to sent a datastream to /dev/null over the serial port to light an LED..)

Doesn't look like it. It appears that USB port is plugged into a hub chip, so you can't just change the function of the pin on the iMX6 to a GPIO.

I'm not terribly familiar with the USB spec, but I can't think of a way offhand to spew data through the USB port to keep the LED on.

I think there IS a way to control power to the USB ports on the Novena, though. I haven't messed with it, but maybe it could be as simple as wiring the LED* to the 5V and GND lines, then use the existing USB control software to toggle that port on and off?

EDIT: *With a resistor as appropriate, of course.

Otherwise running a wire from a nicely-buffered GPIO pin shouldn't be too awful.

Re: Compatible display

It does look like that USB port has its power switch hooked up.  You should be able to control it with novena-usb-hub.