aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Sun Dec 01, 2019 4:32 pm

bird2000 wrote:
Sun Dec 01, 2019 12:19 pm
Thx, than the explanations and the way offered by Peter are correct and MichaRs comments targets to a other context. But the main questions about the new PCB you haven't answered - ETA and location?
ETA= When it's done
Location: Germany

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Thu Dec 26, 2019 2:51 pm

As a little Christmas present I want to show you what I've been working on: the LVDS4PI EVO --> an evolution step of the LVDS4PI.

The EVO has a simpler board layout, simpler DC/DC circuitry and a more advanced LVDS transmitter, now supporting JEIDA and VESA from a single board and with dual-channel LVDS output!
IMG_1171_small.jpg
top view of the LVDS4PI EVO, connected to an RPi4 (mounted in an armor case)
IMG_1171_small.jpg (90.72 KiB) Viewed 3737 times
IMG_1170_small.jpg
LVDS4PI EVO driving a SVGA TFT during testing
IMG_1170_small.jpg (89.34 KiB) Viewed 3737 times

LTolledo
Posts: 4796
Joined: Sat Mar 17, 2018 7:29 am
Location: Anime Heartland

Re: LVDS add-on for Raspberry models with 40pin GPIO

Sun Dec 29, 2019 12:56 am

looks neat! up to what resolution does it support?

I've got a screen from my now defunct Vaio (15" 2K screen) and been looking for LVDS for that.....
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Sun Dec 29, 2019 7:15 am

LTolledo wrote:
Sun Dec 29, 2019 12:56 am
looks neat! up to what resolution does it support?

I've got a screen from my now defunct Vaio (15" 2K screen) and been looking for LVDS for that.....
max resolution supported by the LVDS transmitter is QXGA = 2048×1536pixels.

I've only tested up to FHD (1920x1080) so far.


aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Sat Jan 04, 2020 8:12 am

IMG_1189.jpg
Google Nexus 7 Gen1 display
IMG_1189.jpg (68.61 KiB) Viewed 3474 times
... and yes! It can drive the Nexus 7 Gen1 display too

Raquena
Posts: 15
Joined: Wed Aug 14, 2019 11:11 am

Re: LVDS add-on for Raspberry models with 40pin GPIO

Thu Feb 20, 2020 12:11 pm

Hello guys,

I've found a quite interesting IC for dual LVDS interface.
It seems to have the same functionality as the DS90, at lower cost and smaller footprint.
The problem: The footprint is so small that isn't suitable for regular cheapo PCB manufacturers...

https://datasheet.lcsc.com/szlcsc/1912 ... 410488.pdf

What do you think about it ?

Raquena
Posts: 15
Joined: Wed Aug 14, 2019 11:11 am

Re: LVDS add-on for Raspberry (SINGLE CLOCK, DUAL CLOCK?))

Thu Feb 20, 2020 12:19 pm

Hello again,

I just forgot to ask something else...

There are some screens using two clock differential pairs, some other only use one.
As far as I understood, the ones with two differential pairs are older, and the newer ones are using only one.
To keep backwards compatibility, the DS90C387 has both of them available.

If you only use one of them, the second one is left unconnected, right? (have read somewhere at the datasheet)
When using only one clock differential pair, does require a different DS90C387 pin configuration ???

is that what the DUAL pin is for ???

Sorry for the questions that may be trivial for some.

Thanks!

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Fri Feb 21, 2020 5:40 am

Raquena wrote:
Thu Feb 20, 2020 12:11 pm
Hello guys,

I've found a quite interesting IC for dual LVDS interface.
It seems to have the same functionality as the DS90, at lower cost and smaller footprint.
The problem: The footprint is so small that isn't suitable for regular cheapo PCB manufacturers...

https://datasheet.lcsc.com/szlcsc/1912 ... 410488.pdf

What do you think about it ?
BGA package ... Easy to solder in a reflow oven

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry (SINGLE CLOCK, DUAL CLOCK?))

Fri Feb 21, 2020 5:44 am

Raquena wrote:
Thu Feb 20, 2020 12:19 pm
Hello again,

I just forgot to ask something else...

There are some screens using two clock differential pairs, some other only use one.
As far as I understood, the ones with two differential pairs are older, and the newer ones are using only one.
To keep backwards compatibility, the DS90C387 has both of them available.

If you only use one of them, the second one is left unconnected, right? (have read somewhere at the datasheet)
When using only one clock differential pair, does require a different DS90C387 pin configuration ???

is that what the DUAL pin is for ???

Sorry for the questions that may be trivial for some.

Thanks!
???
Nothing is older or newer! This is dual channel LVDS were odd and even channels have their own clock.
What the pin is used for should be stated in the spec.

Sounds like you do not understand how the LVDS transmitters are working.
IMG_1232.jpg
18.5in FHD (1920x1080pixel) dual-channel LVDS interface driven by LVDS4PI EVO
IMG_1232.jpg (109.21 KiB) Viewed 3128 times
IMG_1233.jpg
close-up of the connector
IMG_1233.jpg (107.06 KiB) Viewed 3128 times
Example above is using an 18.5in Full-HD display module. (spec is here https://www.sharpsde.com/products/displ ... roductview) .
You usually need dual-channel if your displays resolution is bigger than WXGA (1366x768pixels).

Raquena
Posts: 15
Joined: Wed Aug 14, 2019 11:11 am

Re: LVDS add-on for Raspberry models with 40pin GPIO

Tue Feb 25, 2020 1:51 pm

It's not about soldering the IC, that can also be done with a heat gun, even with the hot plate at your kitchen.
The point is the increase of cost of the PCB due to the small via size, small trace size, and very likely layer count.


aBUGSworstnightmare wrote:
Fri Feb 21, 2020 5:40 am
Raquena wrote:
Thu Feb 20, 2020 12:11 pm
Hello guys,

I've found a quite interesting IC for dual LVDS interface.
It seems to have the same functionality as the DS90, at lower cost and smaller footprint.
The problem: The footprint is so small that isn't suitable for regular cheapo PCB manufacturers...

https://datasheet.lcsc.com/szlcsc/1912 ... 410488.pdf

What do you think about it ?
BGA package ... Easy to solder in a reflow oven

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Tue Feb 25, 2020 3:28 pm

Raquena wrote:
Tue Feb 25, 2020 1:51 pm
It's not about soldering the IC, that can also be done with a heat gun, even with the hot plate at your kitchen.
The point is the increase of cost of the PCB due to the small via size, small trace size, and very likely layer count.
As it is a BGA package you will (most likely) end up with 6-layers (might be possible to do the fan-out on 4 layers though) which gives you higher PCB cost for sure. But if you think about a commercial product this should not be a problem.
For DIY it might be a killing point as you need t find a board house with reasonable design rules.

So lower chip cost reult in higher PCB cost (and most likely higher total cost). It's not always the best solution to look for cheapest available single component...

But isn't all about DIY to 'develop' something for three-four times the cost of an off-the shelf product *haha*

Raquena
Posts: 15
Joined: Wed Aug 14, 2019 11:11 am

Re: LVDS add-on for Raspberry (SINGLE CLOCK, DUAL CLOCK?))

Tue Feb 25, 2020 5:18 pm

Indeed you're right,
I don't know how LVDS interface works, and that's why it's being very difficult for me to understand how to set up
this screen:
https://www.cdtech-lcd.com/uploads/2017 ... e00ea6.pdf
(ATTENTION: The link takes very long time to provide the PDF, but it does)
it seems to have 8 differential pairs and a single differential pair for the clock (instead of the expected two pairs).
Details I could find (maybe not related):

I(sort of)managed to make this one run:
https://www.spezial.com/sites/default/f ... aylnn0.pdf
dual_clock_source.PNG
dual_clock_source.PNG (33.51 KiB) Viewed 3018 times
Both clock sources from the DS90 seem to be the same, spitting it at two differential pairs.
clockrate_1clock.PNG
clockrate_1clock.PNG (182.24 KiB) Viewed 3018 times
The screen which has a single clock differential pair has around double clock rate.
clockrate_2clocks.PNG
clockrate_2clocks.PNG (117.76 KiB) Viewed 3018 times
The screen with two clocks has half clock rate as the one with single clock.

Isn't this also a Dual LVDS interface?
Would it be possible to use it with the DS90 IC?
How would the configuration of the DUAL at the DS90 pin be then?
(DUAL = VCC, DUAL = 1/2VCC, DUAL = GND?)

I'm sorry if my questions may sound stupid, but better ask than keep the doubt.

Thanks in advance for your help!
aBUGSworstnightmare wrote:
Fri Feb 21, 2020 5:44 am
Raquena wrote:
Thu Feb 20, 2020 12:19 pm
Hello again,

I just forgot to ask something else...

There are some screens using two clock differential pairs, some other only use one.
As far as I understood, the ones with two differential pairs are older, and the newer ones are using only one.
To keep backwards compatibility, the DS90C387 has both of them available.

If you only use one of them, the second one is left unconnected, right? (have read somewhere at the datasheet)
When using only one clock differential pair, does require a different DS90C387 pin configuration ???

is that what the DUAL pin is for ???

Sorry for the questions that may be trivial for some.

Thanks!
???
Nothing is older or newer! This is dual channel LVDS were odd and even channels have their own clock.
What the pin is used for should be stated in the spec.

Sounds like you do not understand how the LVDS transmitters are working.

IMG_1232.jpg
IMG_1233.jpg
Example above is using an 18.5in Full-HD display module. (spec is here https://www.sharpsde.com/products/displ ... roductview) .
You usually need dual-channel if your displays resolution is bigger than WXGA (1366x768pixels).

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Wed Feb 26, 2020 6:40 am

Your display has a dual channel LVDS interface. It is (most likely) 2/3 of a Full-HD display (either cutted or designed by purpose).

Both LVDS clocks needs to be the same, as one clock is for odd pixels (1,3,5,7..) and the other for even (2,4,6,8..), hence they need to be in perfect sync. One advantage of having two clocks is the reduced frequency, means less EMI.
Your display mapping is VESA, timing also doesn't look very special.

Data sheet of the winstar display is lacking entire timing informations; so happy guessing.

When you speak about DS90 is it this http://www.ti.com/product/DS90C387A?key ... everything ?

As your RPI DPI interface is 24bit input to the transmitter you need to configure (Dual input) it for single pixel input to dual pixel output operation --> VCC/2

Keep in mind that data mapping on DS90C387A is not switchable! So for JEIDA and VESA you will have to have different hardware.

bear2017
Posts: 1
Joined: Wed Mar 18, 2020 2:33 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Wed Mar 18, 2020 2:59 pm

Hi guys,
I found a very smart and neat design with the THC63LVDM83D chip. There is only on DC-DC for back light power. For other high and negative voltages, it use two 555 chips as the charge pump since the load is very light.
Image
The board doesn't has any separate power jack. Instead, it must takes power from the GPIO pins directly.
Image
It was said a 8 inch 1024*768 IPS panel (HJ080IA-01E) was supported by default, which may be ideal for a laptop like usage.
Image
The price of this convertor board itself is under 10 USD. However, it may only be shipped within PRC.
https://item.taobao.com/item.htm?spm=a2 ... 941510515#

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Thu Mar 19, 2020 4:59 am

THC63LVDM83D ( https://www2.mouser.com/ProductDetail/? ... 97wQ%3D%3D ) is a single channel LVDS transmitter, similiar to SN75LVDS83BDGGR, used on my LVDS4PI. Hence you will have the same problems there: you will need different boards for JEIDA and VESA mapping!

FradSer
Posts: 1
Joined: Wed Oct 28, 2020 2:58 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Wed Oct 28, 2020 3:02 pm

aBUGSworstnightmare wrote:
Thu Mar 19, 2020 4:59 am
THC63LVDM83D ( https://www2.mouser.com/ProductDetail/? ... 97wQ%3D%3D ) is a single channel LVDS transmitter, similiar to SN75LVDS83BDGGR, used on my LVDS4PI. Hence you will have the same problems there: you will need different boards for JEIDA and VESA mapping!
Where can I buy your LVDS4PI?

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Sat Oct 31, 2020 6:52 am

FradSer wrote:
Wed Oct 28, 2020 3:02 pm
Where can I buy your LVDS4PI?
I have some spare LVDS4PI EVO (see i.e here viewtopic.php?f=45&t=157109&p=1750126#p1585834) - the more advanced successor of the LVDS4Pi. Let me have your email and I can send you details.


aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Wed Nov 04, 2020 5:55 am

zxcvbs wrote:
Wed Nov 04, 2020 4:39 am
Hi, i can get nearby some spare displays from projectors. any way to use them on the pi?
https://es.aliexpress.com/i/4001083170219.html
at least not an easy/simple one..
But better start a new thread on this as it's not LVDS what you will need

zxcvbs
Posts: 4
Joined: Tue Nov 03, 2020 3:50 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Wed Nov 04, 2020 8:11 pm

Great, can these boards be used with:
55 inchTypea-Si TFT-LCD, LCM
Pixel Format1920(RGB)×1080 [FHD] 40PPIConfigurationRGB Vertical Stripe
https://www.panelook.com/modeldetail.ph ... er_by=desc
LVDS (2 ch, 10-bit) , 51 pins Connector
https://datasheetspdf.com/pdf-file/1312 ... DUN-TGB1/1

Image

aBUGSworstnightmare
Posts: 2550
Joined: Tue Jun 30, 2015 1:35 pm

Re: LVDS add-on for Raspberry models with 40pin GPIO

Thu Nov 05, 2020 5:28 am

zxcvbs wrote:
Wed Nov 04, 2020 8:11 pm
Great, can these boards be used with:
55 inchTypea-Si TFT-LCD, LCM
Pixel Format1920(RGB)×1080 [FHD] 40PPIConfigurationRGB Vertical Stripe
https://www.panelook.com/modeldetail.ph ... er_by=desc
LVDS (2 ch, 10-bit) , 51 pins Connector
https://datasheetspdf.com/pdf-file/1312 ... DUN-TGB1/1

Image
that's a 55in FHD resolution (1920*1080pixel) display with dual-channel LVDS interface, so yes; don't see a blocking point.
The module on the picture below is 18,5in FHD
Image
note that you would need 12V (for the board as well as logic supply of the display) and 24V (for the backlight) power supply, and a suitable interface cable

stevenm3656
Posts: 1
Joined: Thu Dec 10, 2020 11:16 am

Re: LVDS add-on for Raspberry models with 40pin GPIO

Thu Dec 10, 2020 11:20 am

aBUGSworstnightmare wrote:
Thu Nov 05, 2020 5:28 am
Hi aBUGSworstnightmare, hope you are keeping well.

Very impressed with your LVDS4PI EVO project!

Would you be able to send me an email at stevo2020 at gmail dot com regarding the PCB please?

Many thanks,

Steven

MilesPrower1992
Posts: 1
Joined: Fri Jan 22, 2021 3:02 am

Re: LVDS add-on for Raspberry models with 40pin GPIO

Fri Jan 22, 2021 3:25 am

Sorry to post to an old thread, but where can I get one of the LVDS add ons? Do they reduce the GPU performance at all? What's the price of one?

0xCCD
Posts: 1
Joined: Mon Feb 08, 2021 10:33 am

Re: LVDS add-on for Raspberry models with 40pin GPIO

Mon Feb 08, 2021 10:35 am

aBUGSworstnightmare wrote:
Thu Nov 05, 2020 5:28 am
zxcvbs wrote:
Wed Nov 04, 2020 8:11 pm
Great, can these boards be used with:
55 inchTypea-Si TFT-LCD, LCM
Pixel Format1920(RGB)×1080 [FHD] 40PPIConfigurationRGB Vertical Stripe
https://www.panelook.com/modeldetail.ph ... er_by=desc
LVDS (2 ch, 10-bit) , 51 pins Connector
https://datasheetspdf.com/pdf-file/1312 ... DUN-TGB1/1

Image
that's a 55in FHD resolution (1920*1080pixel) display with dual-channel LVDS interface, so yes; don't see a blocking point.
The module on the picture below is 18,5in FHD
Image
note that you would need 12V (for the board as well as logic supply of the display) and 24V (for the backlight) power supply, and a suitable interface cable
I am curious if your board also works for an 6RGW0 from Dell (15.6 " Qhd LED LCD Display Touch Screen Montage 6RGW0 für Dell XPS 15 9530)

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