DS90UB949-Q1: Want to keep GPIO0 at high state during link loss and Serializer restart

Atsushi Hirai

Part Number: DS90UB949-Q1

Hi team,

My customer is using UB949, and using GPIO0 as touch screen interrupt signal from serializer.
They set GPIO0 as Remote-hold mode or Remote-default mode to keep "no interrupt" state during link loss.
However, GPIO0 goes low when the serializer restart by PDB or some reason because the registers are reset to default.
Is there any way to avoid this situation?

If it cannot be solved by software, my customer have to think the solution by hardware. But it's really difficult situation due to the project schedule. Please consider a software solution.

BTW, I consider the false interrupt signal can be masked by HPD output like below. It need hardware change.
Could you check the feasibility? Is there any concern?

Best Regards,

over 4 years ago

+1 Charley Cai over 4 years ago

TI__Genius 12866 points

Hi Atsushi,

No, we dont have a SW solution as PDB will always reset all registers.

The HW option you listed should be ok.

Best Regards,

Charley Cai

0 Atsushi Hirai over 4 years ago in reply to Charley Cai

TI__Expert 5070 points

Charley-san,

Thanks for your advice.

I want one more your advice.

For INTB-pin, is it stably high even if the paired deserializer loss the power or reset by PDB?

Regards,

0 Aaron Heng over 4 years ago in reply to Atsushi Hirai

TI__Mastermind 38070 points

Hi Atsushi-san,

The INTB pin is an open drain output; therefore, you need the pull-up on the serializer side. This INTB signal will always stay HIGH until you configure the INTB and read the status. Once you read the status, it will clear the status and the INTB signal will go LOW.

If you shut off the deserializer or PDB, you will get the link lost. So, if the stage of the INTB signal is LOW, it will stay LOW until you read the status interrupt again. Which mean you are also need to establish the link and configure the INTB in order to get the INTB up and running again.

Hope this helps. Let me know if you have further questions.

Aaron

0 Atsushi Hirai over 4 years ago in reply to Aaron Heng

TI__Expert 5070 points

Aaron-san,

What case I want to know is

"If you shut off the deserializer or PDB, you will get the link lost. So, if the stage of the INTB signal is HIGH, xxxx".

Does INTB on the serializer stay HIGH when the deserializer shut off or PDB reset?

Regards,

0 Casey McCrea over 4 years ago in reply to Atsushi Hirai

TI__Guru** 103215 points

Hello Atsushi-san,

Sorry I just realized that this ticket was assigned to a team member who is no longer in the group. We will check on this for you and respond back within 1-2 days

Best Regards,

Casey

0 Atsushi Hirai over 4 years ago in reply to Casey McCrea

TI__Expert 5070 points

Casey-san,

Got it. I'll wait. Thank you for your support.

0 Casey McCrea over 4 years ago in reply to Atsushi Hirai

TI__Guru** 103215 points

Atsushi-san,

This answer depends on how you have configured the interrupts for the device. By default, INTB is high, since the signal is active low. If there is an interrupt condition enabled in 0xC6, then that conditions occurs, then INTB will go low until you read 0xC7. So for example if you have enabled IE_RXDET_INT (bit 6 in 0xC6), and then you power down the DES, then INTB on 949 will go low.

Best Regards,

Casey

0 Atsushi Hirai over 4 years ago in reply to Casey McCrea

TI__Expert 5070 points

Casey-san,

Which case I want to know is 0xC6[7:0]=0x21(=IE_RX_INT & INT_EN).

Does INTB stay High if Des power down or PDB when there is no interrupt from downstream device?

Regards,

0 Casey McCrea over 4 years ago in reply to Atsushi Hirai

TI__Guru** 103215 points

Hello Atsushi-san,

With that configuration the interrupt will stay high when the 948 powers down, but it will go low when the 948 powers back up and reconnects to the SER

Best Regards,

Casey

0 Atsushi Hirai over 4 years ago in reply to Casey McCrea

TI__Expert 5070 points

Casey-san,

Understood.

In this case, Ser side can distinguish the reason of interrupt which “INTB_IN=Low” or “Reset by PDB or power cycle”, right?

Regards,

0 Casey McCrea over 4 years ago in reply to Atsushi Hirai

TI__Guru** 103215 points

Atsushi-san,

I'm not sure I understand your question here. Can you please explain again?

Best Regards,

Casey

0 Atsushi Hirai over 4 years ago in reply to Casey McCrea

TI__Expert 5070 points

I thought MCU at SER side can distinguishes the source of interrupt by reading 0xC7.

Since 0xC6[7:0]=0x21, IS_RX_INT is reported if downstream device pulls INTB_IN and, no report if the source is reset by power cycle or PDB.

Is my understanding correct?

+1 Casey McCrea over 4 years ago in reply to Atsushi Hirai

TI__Guru** 103215 points

Hello Atsushi-san,

What I see in our setup is that even if IE_RXDET_INT is set to 0, the IS_RXDET_INT will go high when the 948 powers back on after powering off as long as IE_RX_INT is set. I think this is an error in the documentation so we will note it down for future revisions of the datasheet

Best Regards,

Casey

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DS90UB949-Q1: Want to keep GPIO0 at high state during link loss and Serializer restart