DS90UB929-Q1EVM: Is there any way to make HDMI interface to reinit programmatically via I2C

AVorobev

Part Number: DS90UB929-Q1EVM

Hi,

is there any way to make HDMI interface to reinit programmatically via I2C?

I want to upload my EDID structure to the DS90UB929 SRAM using I2C, but I have to replug HDMI cable to force these changes to take effect on HDMI source (PC). Is there any way to do this using only I2C interface?

I suppose the proper way is to toggle HPD pin. But writng to I2C Reset register (Reg addr 0x01) seems not affecting HPD pin.

over 5 years ago

0 Darryl Jeong over 5 years ago

TI__Expert 4210 points

Hello,

I'm looking into the registers to see if this can be done.

0 Darryl Jeong over 5 years ago in reply to Darryl Jeong

TI__Expert 4210 points

I checked on the bench and doing an I2C register 0x01 reset will toggle the HPD.

0 AVorobev over 5 years ago in reply to Darryl Jeong

Prodigy 40 points

Ok, if I load my new EDID and then write 0x10 into 0x1 register it does not affect HPD pin. I tried RESET0, RESET1 and HDMI Reset bits.

Here's my config: Windows 10 PC -> HDMI -> SV600978 Devboard -> FPD-Link -> DS90UB926 -> 854x480 Screen

After powering on I configure remote deserializer and screen via I2C. I see distorted image on the screen because PC sends 720p video stream. It sends 720p because of default SV600978 devboard EDID.

Then I load my EDID into serializer SRAM. PC still detects devboard as 720p receiver. Here if I manually replug HDMI cable then PC detects devboard as 854x480 receiver.

After loading my EDID if you try to reset using different bits on 0x01 register it does not help at all.

The only thing that helps me to reinit HDMI without replugging is:

1) set HPD pin to low for 1 second using GPIO cofigured as open-drain

2) and then write 0x02 value (RESET1) to register 0x01

0 Casey McCrea over 5 years ago in reply to AVorobev

TI__Guru** 102565 points

Hello,

You can de-assert HPD with the following commands:

0x48 = 0x01

0x49 = 0x00

0x4A = 0x00

0x4B = 0x01

0x4C = 0x00

0x4D = 0x00

0x4E = 0x00

You can re-assert it with these commands:

0x48 = 0x01

0x49 = 0x00

0x4A = 0x00

0x4B = 0x01

0x4C = 0x00

0x4D = 0x00

0x4E = 0x01

Best Regards,

Casey

0 AVorobev over 5 years ago in reply to Casey McCrea

Prodigy 40 points

Hello.
Nope. HDP pin didn't toggle after this commands.
Where can I read about this "HDMI APB interface" and what is the purpose of these registers?

0 Casey McCrea over 5 years ago in reply to AVorobev

TI__Guru** 102565 points

Hello,

I just tried this on bench and I can verify it definitely does toggle HPD with the commands I provided. Can you verify that the RX_5V is detected at J16? It should have 5V on it when the HDMI source is connected. The HPD pin is open drain so it can only pull down, not drive high. On the EVM it is pulled up to 5V by the HDMI source.

Best Regards,
Casey

0 AVorobev over 5 years ago in reply to Casey McCrea

Prodigy 40 points

Hello,

This code helped to resolve this issue:

I2CRegWriteByte(Addr1, 0x40, 0x10);
I2CRegWriteByte(Addr1, 0x41, 0x49);
I2CRegWriteByte(Addr1, 0x42, 0x10);
I2CRegWriteByte(Addr1, 0x42, 0x00);

Thread.Sleep(200);

I2CRegWriteByte(Addr1, 0x40, 0x14);
I2CRegWriteByte(Addr1, 0x41, 0x49);
I2CRegWriteByte(Addr1, 0x42, 0x10);
I2CRegWriteByte(Addr1, 0x42, 0x00);

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DS90UB929-Q1EVM: Is there any way to make HDMI interface to reinit programmatically via I2C