TFP401A: Convert LVDS to DVI

Hello, thank you for the reply, I am fairly new to these things but trying to learn. The DVI chipset takes in 24 bit but we get 18 bitsRGB  only how can i do that.

The processor has a module for providing a low voltage differential signaling (LVDS) output interface. This module converts the RGB signals output from video display controller 5 to the LVDS format that has six bits each for R, G, and B signals,
and outputs the converted signals. It has a dedicated phase-locked loop (PLL) circuit, which can generate a clock with a desired frequency by dividing or multiplying the input clock frequency.
The clock output from this PLL can be used as the panel clock for video display controller 5 even when LVDS output is not used. This PLL is called LVDS PLL in this section.
• Four pairs of differential output conforming to the TIA/EIA-644 standard (three pairs for data and one pair for the
clock) 
TXOUT0P
TXOUT0M
TXOUT1P
TXOUT1M
TXCLKOUTP
TXCLKOUTM
TXOUT2P
TXOUT2M

Here i am tring to uses these signals to get an output on my screen that supports DVI since this is 18-bits RGB i dont understand how it will work for a 24bit DVI.

Also in the Processor I am using I have other option 

Graphics

• Number of graphic planes: Four planes (graphics 0, graphics 1, graphics 2, and graphics 3)

• Supported pixel formats:

-RGB565 progressive format (α: none, R: 5 bits, G: 6 bits, B: 5 bits; 16 bits in total)

- RGB888 progressive format (α: none, R: 8 bits, G: 8 bits, B: 8 bits; 24 bits in total)

- α RGB1555 progressive format (α: 1 bit, R: 5 bits, G: 5 bits, B: 5 bits; 16 bits in total)

- α RGB4444 progressive format (α: 4 bits, R: 4 bits, G: 4 bits, B: 4 bits; 16 bits in total)

- α RGB8888 progressive format (α: 8 bits, R: 8 bits, G: 8 bits, B: 8 bits; 32 bits in total)

- RGBα5551 progressive format (R: 5 bits, G: 5 bits, B: 5 bits, α: 1 bit; 16 bits in total)

- RGBα8888 progressive format (R: 8 bits, G: 8 bits, B: 8 bits, α: 8 bits; 32 bits in total)

- CLUT8 progressive format (CLUT: 8 bits) - CLUT4 progressive format (CLUT: 4 bits)

- CLUT1 progressive format (CLUT: 1 bits)

- YCbCr422 progressive format (Y: 8 bits, Cb/Cr: 8 bits; 16 bits in total) (only for graphics 0 and 1)

- YCbCr444 progressive format (Y: 8 bits, Cb/Cr: 8 bits; 16 bits in total) (only for graphics 0 and 1)

• Maximum image size to be read: 1440 pixels × 1440 lines (horizontal × vertical)

Output video image format

• RGB888 progressive video output (24-bit parallel output)

• RGB666 progressive video output (18-bit parallel output)

• RGB565 progressive video output (16-bit parallel output)

• RGB888 progressive video output (8-bit serial output)

what TI chipset would you recommend for me to use these signals in order to get an output on my screen with DVI

Hi Salim,

Sorry it looks like the link I included in my last post is broken, ignore that.

To my understanding, you are trying to convert the LVDS output from your processor to DVI input for your screen, and the color depth is RGB666 for 18-bits RGB. Can you share the datasheet or whatever document you have that has this information?

From the above assumptions, I believe you can use the SN75LVDS86A and TFP410 for your application.

The SN75LVDS86A converts the LVDS from the processor to RGB. The TFP410 then converts the RGB to DVI. You need both of these since we don't have a single device that can do LVDS->DVI.

So the signal path will look like:
Processor -> SN75LVDS86A -> TFP410 -> Screen

There may be parts other than the SN75LVDS86A better suited for this application, but I would like to see the processor documentation before making any other recommendations. Please also note that we need to ensure that the pixel clock frequencies for these devices can support your screen, so I also need to know what screen resolution you are trying to realize.

Regards,
I.K.

www.renesas.com/.../r01uh0403ej0400_rz_a1h.pdf

This is the processor that we are looking for
according to the data sheet it can give me RGB888 for 24-bit RGB( can be found under video display controller)
I have a kit for the same but the proble is it has and LVDS connector and all I am trying to do is instead of LVDS get it as DVI , If there is any other better conversion like HDMI or anything then please do share.

So I came across few TI chipsets to get this LVDS to DVI conversion but couldnt figure out how i can get the RGB666 data to work with TFP410 which takes in 24-bit RGB

Hi Salim,

There's no issue with using RGB666 data with the TFP410. The unused inputs can just be tied to ground.

Looking at the block diagram in the datasheet of the processor on page 2270, it looks like the frequency range of the LVDS output clock is 13.40 to 87 MHz.

In this case, the DS90CR218A is a better choice, and the frequency also needs to be kept above 25 MHz for the TFP410.

So your solution will look like:

Processor --> DS90CR218A(www.ti.com/.../ds90cr218a.pdf) --> TFP410(www.ti.com/.../tfp410.pdf) --> Screen

For the pixel mapping, see Figure 40.5 and Table 37.7 in your processor datasheet. You can also reference this app note: www.ti.com/.../snla014a.pdf

Regards,
I.K.

Hello I.K,

You have been a great help, I will definitely look into the soltion you suggested which is
Processor --> DS90CR218A(www.ti.com/.../ds90cr218a.pdf) --> TFP410(www.ti.com/.../tfp410.pdf) --> Screen

Just trying to explore other options here, this solution is good if i use the signals coming from the LVDS module correct?
What if i just use the values of RGB888 from the video interface controller module and directly use TFP410?? will it still be a good solution?

In doing so i dont have to go from video inteface controller module --> LVDS module-->DS90CR218A-->TFP410-->Screen
instead I can just do video inteface controller module --> TFP410-->Screen.


Is this a possibility. Again I am not an expert about these concepts and i am fairly new I could use all the help and really appreciate your suggestions and comments.