DS90UB928QEVM: Setting GPIO Register But GPIO pins no output response

WenHung Wang

Prodigy 200 points

Part Number: DS90UB928QEVM

Hi TI Team:

I design Deserializer 928 in our project.

Right now, we can talk the all register by I2C.

As for GPIO, we can write it. But all GPIO do not output what I set in register.

For example, I want to set GPIO 7 to be high. So I set register address 0x21h to be 0x09h. GPIO 7 should be High but it does not.

How to solve the problem? Looking forward to your feedback.

By the way, we do not use serializer IC to connect Deserializer by FPD-Link cable and just only Deserializer initial testing. I'm not sure if we can only set GPIO register to let GPIO work without serializer connection.

over 6 years ago

0 Charley Cai over 6 years ago

TI__Genius 12866 points

Hi Wenhung,
Can you attached a picture of your EVM?
I tried the setup on my 928EVM following the same register settings, and the GPIO does output High voltage.

Best Regards,
Charley Cai

0 WenHung Wang over 6 years ago in reply to Charley Cai

Prodigy 200 points

Hi Charley Cai:

Many thanks for your feedback.

The attachment is our register table setting. FYR.

Could you help me to check that if I miss something to cause GPIO output no response?

2235.Deserializer928 Register Teable.xlsx

0 Charley Cai over 6 years ago in reply to WenHung Wang

TI__Genius 12866 points

Your register 0x21 is set to 0x91, so GPIO7 is not configured as High. GPIO8 is.
Can you measure GPIO8 output?

Best Regards,
Charley Cai

0 WenHung Wang over 6 years ago in reply to Charley Cai

Prodigy 200 points

Dear Charley Cai:
Sorry to let you confused. The previous setting is my old setting. I had changed 0x21 to be 0x99 and 0x98.
But the symptom is the same and no output response.
Could you help me if there is any setting I missed?

Thanks a lot.

0 WenHung Wang over 6 years ago in reply to WenHung Wang

Prodigy 200 points

Hi Charley Cai:
By the way, I also tried to set GPIO5~8 to be high but all output are always Low.
Looking forward to your feedback.

Thanks a lot.

0 Charley Cai over 6 years ago in reply to WenHung Wang

TI__Genius 12866 points

Could you let me know your EVM version, or provide a picture of the EVM?

Best Regards,
Charley Cai

0 WenHung Wang over 6 years ago in reply to Charley Cai

Prodigy 200 points

I don't have EVM board. I had designed the chip on our product. Right now, I'm testing it and got this problem.
So I need your experience to solve the issue.
Thanks a lot.

0 Charley Cai over 6 years ago in reply to WenHung Wang

TI__Genius 12866 points

Could you share the schematic?
The register setting for GPIO is correct.

Best Regards,
Charley Cai

0 WenHung Wang over 6 years ago in reply to Charley Cai

Prodigy 200 points

The attachment is schematic for Deserualizer. FYR

PCBa Schematic_v9.2.pdf

0 Charley Cai over 6 years ago in reply to WenHung Wang

TI__Genius 12866 points

Do you have external connection on the GPIO pins that's pulling them down?
I see there are some 10k pull down resistors on GPIO pins.

Are you measuring at 928 pin or somewhere else?

Best Regards,
Charley Cai

0 WenHung Wang over 6 years ago in reply to Charley Cai

Prodigy 200 points

Yes, my GPIO pins have external resistor to pulling down. But I try to remove them and add resistor to pulling high.
GPIO still cannot be pulled high. I don't know why.
Besides, I also remove related connection with GPIO, which means I let GPIO to be floating, But it is still no response.

0 WenHung Wang over 6 years ago in reply to WenHung Wang

Prodigy 200 points

Hi Charley Cai:

I studied Deserializer 928 Spec (SNLS440C –MARCH 2013–REVISED JULY 2016) again. there is a table showed in page 31 and I attached a picture below.

Does it mean I have to connect Serializer with FPD-link to let Serial input active and PDB/OEN/OSS_SEL to be high and then the GPIO of deserializer will be valid?

0 Charley Cai over 6 years ago in reply to WenHung Wang

TI__Genius 12866 points

If you are only programming the GPIO locally, you shouldn't need a link.

You said that
" I try to remove them and add resistor to pulling high.
GPIO still cannot be pulled high. I don't know why. "

If the GPIO is pulled to high and you still get low signal, I would suspect there is a short somewhere on your board.

Best Regards,
Charley Cai

0 WenHung Wang over 6 years ago in reply to Charley Cai

Prodigy 200 points

Hello Charley Cai:

Many thanks your support. I checked that and no short issue.

Now, I can configure GPIO. The root cause is that OEN/OSS_SEL have to pull-high. Before that these 2 pins are pull-down.

So the problem is solved and thanks your support these days.

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DS90UB928QEVM: Setting GPIO Register But GPIO pins no output response