DS90UH940-Q1: How to configure GPIO0 ?

Hi PY,

All 94x device has a similar mechanism configuring the GPIO. Please follow the instruction here from my previous thread, but do not enable 18-bit mode.

https://e2e.ti.com/support/interface/f/interface-forum/899426/ds90ub947-q1evm-gpio-issue-in-18-bit-video-mode

Aaron

Hi Aaron,

One question for the instruction that shown in the link you provided. 

Step #5 said "Forcing deserializer capabilities in 947 by programming the register 0x20 = 0x8A."

Our serializer is DS90UH925, from 925 datasheet we can not see register 0x20. What should we do for Step #5 with 925 ? 

PYTsai,

From your previous post, you mentioned:

PYTsai said:

However when we send a 3.3V signal to GPIO0 it will be pulled to 1.1V. 

What exactly do you mean by this? Do you mean on the 940 side, when you try to pull the pin to 3.3V as the GPIO input, it is getting forced down to 1.1V? Or are you saying that the incorrect voltage is coming on the 925 side when the 940 input GPIO is driven high? 

Best Regards,

Casey 

Hi Casey,

Yes, when we try to pull the 940 GPIO0 pin to 3.3V as the GPIO input, 940 GPIO0 pin is getting forced down to 1.1V

Need team's help to review our setting if any configuration missed for 940 to send GPIO0 to 925 GPIO0 ? 

Will it possible that when 940 connect with 925, the 940 GPIO0 will not work ? need team to clarify this also. thanks!

Hi Casey,

Today, we use 940 and 925 EVM to do test. We can make GPIO1 works. However similar setting GPIO0 not work. 

           DS90UH940 0x1D[3:0]=0x03

           DS90UH925 0x12[2]=1

           DS90UH925 0x0D[3:0]=0x5

Can you help provide us a set of setting for configuring 940 GPIO0 as input and 925 GPIO0 as output? 

Hello PY, 

Upon inspection I don't see anything wrong with your configuration but we don't currently have a 925->940 setup to try this on our end. We will put something together to spot check this and get back to you in ~1week 

Best Regards,

Casey 

Hi Casey,

OK, thanks!

Hello PY,

Thank you for your patience as we debug this

Best Regards,

Casey 

Hi Casey,

Is there any finding on this issue ? 

Closing this thread since discussion has moved to email. I will update this thread with the results when we make a conlusion 

Best Regards,

Casey