DS90UH947-Q1: DS90UH947-Q1, compatibility with DS90UH928-Q1

Angelo,
What is your PCLK frequency?

The DS90UH947 serializer is backwards compatible to the DS90UH926 and DS90UH928 deserializers for openLDI clock frequencies of 25 to 85MHz.
This is from the 947 datasheet:

8.3.12 Backward Compatibility
This FPD-Link III serializer is backward compatible to the DS90UB926Q-Q1 and DS90UB928Q-Q1 for OpenLDI
clock frequencies ranging from 25MHz to 85MHz. Backward compatibility does not need to be enabled. When
paired with a backward compatible device, the serializer will auto-detect to 1-lane FPD-Link III on the primary
channel (DOUT0±).

Hello,

thanks for the support.

We actually have a pixelclock 43200000 (for a 1280 x 480 display).

What we are trying to do is to connect a "single link" cable, from 947 port 0, to a single link deserializer (928). So we configured the 947 as signle link. 

Checking general status register, we get 0x16, so no link.

What we should do with the other unconnected data pair ?

Another strange thing is that resetting the 947 from the RESET register (writing 0x01), it does not come back up anymore.

We also did an additional test and connect the board to a test fixture with a 948 deserializer (so dual link, dual channels) we still have general config 0x04 (stil no cable link). At this point we may have some circuit error from the serializer to the connector ? 

Hello,

we have an update:

one major issue was 2 wires swapped between different channels before the dual fpd-link connector.

We tried a fix on the pcb, we had link sometime now, but still with crc errors (general status 0x17 sometimes, or 0x16).

Is it possible the manual fix cannot work for such frequencies ?

Still, we cannot SW reset the device with 0x01 on REG_RESET, the device never comes buck up again after the reset.

Tbanks

angelo