DS90UH940N-Q1: DS90UH940N-Q1 FPD-LINK III RX input instability，in this unstable process use I2C to write and read register，DS90UH940N-Q1 abnormal.

Hi Jian,

Do you know its partner device? Did you follow the power sequence? When you in abnormal case, can you please monitor the lock pin?

Aaron

HI，

1、 partner device is DS90UB941AS-Q1，DS90UB941AS-Q1 has an unstable power-on process，in this unstable process use I2C to write and read register，DS90UH940N-Q1 abnormal.

2、I use I2C to control DS90UB941AS-Q1，write 0x5B value is 0x01，FPD3_TX_MODE forced single FPD-Link III transmiter mode。DS90UB941AS-Q1 transmit 1280*720@60 signal，but DS90UH940N-Q1 cdr no lock。How to configure DS90UB941AS-Q1 single FPD-Link III transmiter .

Hi Jian,

You can strap the 941AS to independent mode. In your case, it looks like you do not have a stable lock. If it is, your I2C will break. Can you get both register dump for 941AS and 940? Thanks.

Aaron

HI，

 941AS and 940 are configured independentity， DS90UB941AS-Q1 transfer unstable，in DS90UB941AS-Q1 transfer unstable process use I2C to read DS90UH940N-Q1 register,does it lead to DS90UH940N-Q1 die?

Hi Jian,

If you are getting inconsistent reading of I2C transaction, this could lead to that you do not have a stable link. Can you monitor the lock pin of the 940N if you have a stable lock?

Aaron

Will I2C hanging on the 940 also cause this problem？

Hi Jian,

Did you have a chance to verify per my suggestions? If you can't communicate across the 940, the root cause comes down to unstable link or devices strapping for IDx. You may also try to read on 940 side if you think 940 causes the I2C.

Aaron