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HDMI or DVI-D (Dual Link) to LVDS Conversion for 10-bit LCD Panels
I've just registered and this is my first post - a little about me at the end.
I am hoping to prototype a quite basic picture monitor for high-end applications. A picture monitor differs from a TV in that it has no provision for audio and does not include a tuner; it differs from a computer monitor in that it is designed to accept a video format rather than a PC format signal. In CRT technology, picture monitors were designed to add nothing to, or take anything away from, the signals fed to them and used bespoke high resolution CRTs - often with the original delta gun arrangement - and (in Europe) the correct "EBU" phosphors for accurate colorimetry.
My LCD picture monitor would be used with a Lumagen Radiance XE 10-bit video processor which would act as a switcher, take care of deinterlacing of interlaced inputs, upscale standard definition inputs, manage colour and gamma - and always output 1920 x 1080 progressive at 50Hz on HDMI.
I am still to choose my LCD panel - I am looking for: 32 inch : 1920 x 1080 : 50Hz : 10-bit : S-IPS or AS-IPS. I still have some research to do regarding refresh rate and number of bits. To preserve picture quality I want to avoid frame-rate conversion and work at 50Hz throughout, but the video processor can convert to 60Hz if I have to work 60Hz. I'm not sure if true 10-bit (total: 30 bits) panels are available - it seems many 10-bit panels are actually dithered 8-bit (total: 24 bits) panels. There are two products - a Sony LMD3250MD 32" medical grade monitor and an Ikegami HLM-3250W 32" broadcast grade monitor - which claim to use 10-bit panels which I am investigating.
So, in principle, this is a straightforward task and, once I've chosen my LCD panel, all I need is a means of converting the HDMI signal from the Lumagen Radiance XE video processor to the (multi-port) LVDS signals required by the panel. I'm not sure yet whether the converter will need a control interface but think this is likely as with ICS's NT15H LCD Controller Board and multi-button NK05A OSD Control Board - see http://www.icsco.kr/what_we_serve/sub_02.asp
So, to summarise I need:
Can't be that difficult... can it?
About me: I'm a semi-retired, degree-qualified electronics engineer - I graduated from Imperial College, London in 1979 and then joined BBC TV where I worked as an engineer in their London television studios on the full range of broadcast equipment and have some 30 years' experience designing, building, repairing and modifying professional and consumer electronics. In 1987 I moved to Channel 4 TV, London where I worked until 2006, at the end as manager of the team of engineers which kept the transmission operations running.
i am having an lvds ouput signal from the board which i want to convert to dvi signal in
Is your LVDS 2-channel or 1-channel? In other words, does it have 3-4 data lanes, or 6-8?
If it's 2-channel, it won't be easy to convert it to DVI, since our DVI transmitter (the TFP410) has a 24-bit data input, and 2-channel LVDS receivers often output 48-bit data.
If it's 1-channel, it should be straightforward to convert it to DVI, but your pixel clock frequency range will be limited, which limits your possible resolutions. Most 1-channel receivers have a max frequency of 85MHz, which gets you up to 1366x768.
Can your graphics source output RGB instead of LVDS? If so, it would probably be easier to use the RGB output with the TFP410, for a fully capable DVI transmitter.
We have a device planned that may meet your requirements- please contact me at jay.canteenwala<at>TI<dotcom>
and we can continue the discussion
the board which i am using has a single channel lvds output.it doesnt have rgb output.
If your LVDS is 8 or 6 bit color the conversion to DVI can be done with a two chip solution. If your LVDS is 10-bit color the two chip solution will still work, but you will lose some color depth in the process and end up with 8-bit color.
The two chip solution will deserialize the LVDS to RGB data, which is then fed to a TMDS transmitter.
Any of the chips mentioned below would be paired with a TFP410 TMDS transmitter. Depending on the resolution of the displays and the corresponding pixel clock speed you want to use you can use the following parts to deserialize the incoming LVDS data:
For 6-bit color (RGB-666):
- DS90CR218A, clock range of 12-85 MHz, latches out data on rising clock edge only
- DS90CF366, clock range of 20 - 85 MHz, latches out data on the falling clock edge only
For 8-bit color (RGB-888):
-DS90CR288A, clock range of 20-85 MHz, latches out data on the rising clock edge only
-DS90CF386, clock range of 20-85 MHz, latches out data on the falling clock edge only
If you need a higher clock speed, then the following parts could also be considered:
- DS90CR486, clock range of 66 - 133 MHz, latches out data on the rising clock edge only
- DS90CR484A, clock range of 33 - 112 MHz, latches out data on the rising clock edge only
- DS90CF388, clock range of 40 - 112 MHz, latches out data on the falling clock edge only
The devices with the high clock speed support dual pixel interfaces. If necessary you can tie off any unused inputs. The draw back to these higher speed parts is the added board space due to the unused channels.
DPS APPS / SVA
thank you for your reply i wanted to know if there are any evaluation boards or converter boards which perform lvds to dvi conversion.i also saw an ic chip chrontel(ch7036 ) which converts lvds to dvi as well as hdmi are any evaluation boards presnt for this chip which i can use for conversion purpose
Nisha, do you know the max clock frequency of your LVDS source?
We can provide 2 EVMs (one for LVDS RX, one for TMDS TX) that you can connect together.
hi thge board which i am using has TI-OMAP 3530 Cortex-A8 having a frequency of 600 Mhz
Thanks but I was actually asking about the max pixel clock frequency of the LVDS output. It's probably somewhere between 25-100MHz. Or if you don't have that info, maybe you can tell me the max resolution supported by the LVDS output.
max resolution supported by my board is 1280X 800
Ok; that commonly uses a 71MHz pixel clock. 1 last question: do you have 3 or 4 LVDS data lanes (18-bit or 24-bit color)?
With this info, hopefully we can get you the most suitable EVMs.
the board has 4 lvds channels and it has 24 bit colour input
Nisha, please send me an email at reisenbeis <at> ti <dotcom>, and we'll arrange to send you EVMs that do LVDS to DVI conversion at 1280x800.
sorry for the late reply, my email id is firstname.lastname@example.org
This is exactly what I was looking for. Thanks for making my research that much easier!
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