DS90UB947-Q1: Register:0x5A 's value will change to 0x00 auto automatically

Yao YunXuan

Hi Team,

I came to seek help, we designed a new solution which 947 and MAX9286（MAXIM） at the same i2c bus.

In normal circumstances, the 947 and 9286 are all used for slave device, the value of 947's register:0x5A is 0xCD, but 9286 would change to host device in some use case automatically.

In this time, 9286 would send hundreds of 0x00 to i2c bus, and then the value of 947's register:0x5A would change to 0x00 suddenly.

I can not understand why the value of 0x5A will change to 0x00, then I had to force to reinitialize the 947.

Can you give me some suggestions to help me stop the value of 0x5A change to 0x00 suddenly.

These are the i2c message:

0x18,0x5A;

0x19,0x00;

Best Regards.

over 3 years ago

0 Gil Abarca Ramos over 3 years ago

TI__Genius 16750 points

Hi Yao,

Can you send me a Saleae capture of the I2C bus where you see this problem happening.

Best Regards,

Gil Abarca

0 Yao YunXuan over 2 years ago in reply to Gil Abarca Ramos

Prodigy 200 points

Hi Abarca,

These are the Saleae capture of the I2C bus and the txt log.

Best Regards.

1665.Desktop.rar

0 Gil Abarca Ramos over 2 years ago in reply to Yao YunXuan

TI__Genius 16750 points

Hi Yao,

I am looking at the saleae capture; however, I need more information:

1. Can you make a diagram of your setup. Are you connecting the MAXIM part to the 947.

2. What pullup resistors do you have in the I2C bust for 947?

3. Can you share the schematic?

4. Is the MAXIM part writing 0xCD to register 0x5A in the 947?

Best regards,

Gil Abarca

0 Yao YunXuan over 2 years ago in reply to Gil Abarca Ramos

Prodigy 200 points

Hi Abarca,

1.The MAXIM 9286 and 947 both connect to a soc chip (design for host device);

2.The pullup in blow screenshot;

3.we can only share the screenshot of schematic, is it usefully?

4.I checked the i2c message and did not found MAXIM part will writing message to 0x0C (947 's address)

Best Regards.

0 Yao YunXuan over 2 years ago in reply to Gil Abarca Ramos

Prodigy 200 points

Sorry this the screenshot of schematic

0 Gil Abarca Ramos over 2 years ago in reply to Yao YunXuan

TI__Genius 16750 points

Hi Yao,

Can you provide a saleae trace showing the I2C activity when you are trying to dump the 947 register after the MAX9286 sends all the 0's?

Best Regards,

Gil Abarca

0 Yao YunXuan over 2 years ago in reply to Gil Abarca Ramos

Prodigy 200 points

Hi Abarca,

This is the saleae trace, please help to check it, wish you suggestion.

Best Regards.

4572.rar

0 Gil Abarca Ramos over 2 years ago in reply to Yao YunXuan

TI__Genius 16750 points

Hi Yao,

I am looking at all the information and speaking with my team. I will get back to you with any updates by the end of this week.

Best Regards,

Gil Abarca

0 Gil Abarca Ramos over 2 years ago in reply to Gil Abarca Ramos

TI__Genius 16750 points

Hi Yao,

It is unclear is why this happens. Can you remove the Maxim part and send the register dump?

Best Regards,

Gil Abarca

0 Yao YunXuan over 2 years ago in reply to Gil Abarca Ramos

Prodigy 200 points

Hi Abarca,

This is the register dump without Maxim part.

Best Regards.947 without max9286.rar

0 Gil Abarca Ramos over 2 years ago in reply to Yao YunXuan

TI__Genius 16750 points

Hi Yao,

This is the last read to the 947:

You can still read the content of the FPD-Link device. The UB947 appears to be working normal now that the GMSL device has been depopulated. It seems that the GMSL device is causing the issue. I would recommend you to debug the GMSL device.

Best Regards,

Gil Abarca

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DS90UB947-Q1: Register:0x5A 's value will change to 0x00 auto automatically