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tsourekis , 08-06-2019, 08:52 AM

Hi all,

I have started thinking about a design with the STM32MP157 and I noticed they use an HDMI transmitter to convert he 24-bit RGB coming from the TFT controller to HDMI with audio embedded. They use a device by Lattice Semi - the SiL9022A (https://www.semiconductorstore.com/p...iI9022a_pb.pdf).

The issue is, I can't find any reference designs or any reference manuals since this requires an HDMI licence. The solution so far is to use the TFP410 by Texas Instruments (HDMI Transmitter without audio embedded) and then use a audio codec to drive some speakers and headphones. Basically the solution provides with an HDMI output without sound.

Anyone have any suggestions or a workaround? I have been searching for a few days now and nothing.

Thanks.

robertferanec , 08-07-2019, 02:15 AM

They have PDF schematic - that should be helpful: https://www.st.com/content/ccc/resou..._Schematic.pdf

Here I found datasheet: https://datasheet.lcsc.com/szlcsc/19...NU_C369574.pdf

They, also have full design files from the STM development kit, where you can check layout: https://www.st.com/resource/en/board...mb1272_bdp.zip

These three files (schematic, datasheet, whole project) should be good enough to use it on your board.

PS: If I would need HDMI, I would probably find the main MCU / CPU with HDMI output. The SiI9022ACNU chip costs 10 dollars (same price as the STM chip), it will take space on your board, increase power consumption, etc.

tsourekis , 08-07-2019, 02:28 AM

Hi Robert,

Thanks for your reply. I have seen the complete designs you have suggested - I meant I couldn't find reference designs for the Sil9022A (I see I didn't explain it well above ) I think I would probably move towards choosing a CPU with HDMI output rather than getting the HDMI transmitter. I was thinking of the i.MX8M as an alternative. Unless you can suggest something equivalent to the SMT32MP1 from your experience?

Thanks!

robertferanec , 08-09-2019, 08:31 AM

I usually pick MCU / CPU based on several factors e.g. peripherals and pins needed for my application, price, development kit with full documentation (including source code of schematic and pcb), software development kit (to make it easier to start with software), a lot of documentation and application notes available (e.g. design guides, how to compile and customize software, etc).

So that is what I would compare.

PS: I have not done any design in iMX8 yet and I am not sure if there are STM chips with HDMI - I have not use that chips. So I am not the best person to advice