TFP401A-Q1: Driving display shadowing, mismatch

Hatice Kilci

Part Number: TFP401A-Q1
Other Parts Discussed in Thread: TFP401

Hell,

I am using the TFP401A-Q1 to drive an RGB display. I am using the HDMI signals from Raspberry Pi compute module 4. I tried changing the resolution using hdmi_cvt command but it didn't work. The colors appear correctly on the display. There are shadow letters, a kind of double image problem.

I used the DE and Mode pins, but I didn't connect the HSYNC and VSYNC on my test board because the display manufacturer advised that when using DE mode, the HYSNC and VSYNC pins should be left unconnected.

How can I solve the double image problem?

Thanks.

4 months ago

0 David (ASIC) Liu 4 months ago

TI__Guru**** 183811 points

Hi,

Have you tried lower resolution such as 800x600? Does it also have this double image problem?

Can you please share your schematic and layout?

Thanks

David

0 Hatice Kilci 4 months ago in reply to David (ASIC) Liu

Prodigy 30 points

Yes , I tried lower resolution and changed the config_hdmi_boost as 11 and this problem is solved. Thanks.

0 David (ASIC) Liu 4 months ago in reply to Hatice Kilci

TI__Guru**** 183811 points

Hi,

Is this issue now fully resolved or do you need any additional support?

Thanks

David

0 Hatice Kilci 4 months ago in reply to David (ASIC) Liu

Prodigy 30 points

Hello,

The shadows disappeared for now. I am trying to reach rhe EEPROM and I want to use EDID version.

0 David (ASIC) Liu 4 months ago in reply to Hatice Kilci

TI__Guru**** 183811 points

Hi,

The TFP401-Q1 is not involved in the EDID communication, this communication is handled directly by the GPU with the Panel, usually most panels implements an internal EEPROM with all the EDID information. If the panel does not have an internal EEPROM, you can use an external EEPROM.

The TFP401 will just receive and deserialize the incoming TMDS signal regardless of the resolution.

Thanks

David

0 Hatice Kilci 4 months ago in reply to David (ASIC) Liu

Prodigy 30 points

Hello David,

I added the external EEPROM, but I connected the 4.7 kΩ pull-up resistors to 3.3 VDC. I need to change the voltage level to 5 VDC because the EDID configuration requires a weak pull-up to 5 VDC.

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TFP401A-Q1: Driving display shadowing, mismatch