DS90UB947-Q1: Short cut detection

Fernando Pinto

Part Number: DS90UB947-Q1

Dear sirs,

I'm using the serializer DS90UB947Q in FPD-Link connection, on base in the image and the parameters the devices uses the Dual link, but unfortunately I have a short-circuit between the RIN1- with the ground.

Today I tested to read the register 0x0C and I got the value 0x17, if I unplug the cable the value is 0x16. As you said, the serializer can detect the when the pins are with the short curt to ground or the battery, in my case I have sometimes the Rin1- to the ground or Rin1+ to ground, but the device can't detect and always send the picture to the target device. I'm using the two channel of FPD-Link III.

There are any configuration to force to detect my short cuts as image in attactment.

Regards,

Fernando Pinto

over 2 years ago

0 Shu Huang over 2 years ago

TI__Mastermind 18046 points

Hi Fernando,

When you read register 0x0C, did you set the below PORT1_SEL bit in register 0x1E? Since the default on 0x0C is to detect port 0 and RIN1- is what is shorted, I'd like to verify if the 0x17 value was read from Port 0 or Port 1.

Best,

Shu

0 Fernando Pinto over 2 years ago in reply to Shu Huang

Prodigy 10 points

Hi Shu,

Today I tested and I was checking the Pair 0, when I wrote in register 0x02, I got 0x16 in register 0x0C but sometimes when I refresh I got 0x17.
Do you know why I have this value floating?

Regards,
Fernando Pinto

0 Shu Huang over 2 years ago in reply to Fernando Pinto

TI__Mastermind 18046 points

Hi Fernando,

Apologies, I mistakenly typed the decimal address instead of the hex address. Want to clarify that you experienced the floating value after setting register 0x1E to 0x02 to enable PORT 1 and reading from 0x0C?

Best,

Shu

0 Fernando Pinto over 2 years ago in reply to Shu Huang

Prodigy 10 points

Hi Shu,

I understood the mistake.

Yes when I read the register 0x0C with value 0x02 in register 0x1E the value is floating in the first bit (detect the cable is or not connected), because in Port 1 I have the short-cut because of the automatic welding.

I thought maybe there is a better register to check this kind of fault, but I didn´t find nothing in the datasheet device.

Regards,
Fernando Pinto

0 Shu Huang over 2 years ago in reply to Fernando Pinto

TI__Mastermind 18046 points

Hi Fernando,

I will double check with the team if there is a better method, this is the only one I am aware of.

Best,

Shu

0 Fernando Pinto over 2 years ago in reply to Shu Huang

Prodigy 10 points

Thanks so much Shu

+1 Shu Huang over 2 years ago in reply to Fernando Pinto

TI__Mastermind 18046 points

Hi Fernando,

I checked with the team, register 0x0C bit 0 does a very basic check if there are any toggling happening on the back channel. In this case, the floating value caused by the short may be due to reflections and potential swings on the RIN1- pin. Unfortunately, for this device, there are not better mechanisms for kind of link fault detection.

We recommend polling 0x0C multiple times as a workaround to confirm detection but there are not any other registers.

Best,

Shu

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DS90UB947-Q1: Short cut detection