AM4376: AM4376 DSS Hsync Alignment to Vsync, active edges.

Hi Barrie,

The AM4376 DSS does not support this type of alignment. The signals can be changed to active high or low using the IHS and IVS bits, but you cannot change edge transitions.

Best,

Andrei

the non-standard sync alignment of the AM4376 seems to break HDMI compliance (CTS 7-25 Video Format timing) can you offer any other ideas how to fix? 
strobe polarity is part of this testing.

Thanks
Barrie

Hi Barrie, 

AM4376 does not natively support HDMI, you need to use a HDMI transmitter that converts the DSS RGB output to a valid HDMI signal. On the AM437x EVM, a SIL9022A is used. That device can generate DE, HSYNC and VSYNC pulses using it's "Embedded Sync Decoding" logic block. 

As long as that device is fed in a format that it supports (of which there are several), then it should produce a valid HDMI output. 

We are using the SIL9022A, per the EVM. Did the EVM meet CTS?

The caveat, the SIL9022A transmitter can create DE, HSYNC, and VSYNC signals using the start of active video (SAV) and end of active video (EAV) codes within the ITU-R BT.656-format video stream, which I don't think the AM4376 DSS supports.

HDMI would not have been something that was characterized on AM437x since it's not a native interface, there was most likely only a functional validation of HDMI functionality on the EVM. 

I would try reaching out to the the HDMI transmitter manufacturer to inquire about their supported input video modes.