Part Number: DS90UB949-Q1
We are currently evaluating the DS90UB949 serializer in our development setup with the DS90UH948 deserializer and an external EDID EEPROM. We have observed the following behavior:
- When we perform a normal power-up or toggle the PDB pin cleanly, the HPD pin does not go high immediately, even though the I²C interface is accessible.
- If we short the PDB capacitor to reset the serializer, the HPD pin goes high immediately, but the I²C bus becomes unresponsive and all register reads fail.
- This issue occurs only when the 948 deserializer is connected to the 949 serializer.
Our questions:
- What is the recommended method to safely assert HPD after a reset without causing I²C timeouts?
- Is there a software-based reset sequence we can use via I²C to initialize the 949 while ensuring HPD goes high?
- Could you provide guidance on timing requirements between PDB release, HPD assertion, and I²C readiness for a 949 → 948 link with external EDID?
