DS90UH940-Q1: REMOTE_ID register configuration

Harsha Manjula Mallikarjun

Part Number: DS90UH940-Q1

Hi,

ds90uh940 is the onboard chip to which we have connected ds90uh929 over fpd link. From deserializer side (ds90uh940) we want to configure i2c address of ds90uh929. From the data sheet I understand REMOTE_ID register can be used for this purpose along with FREEZE ID bit set. But, it is not working the way I am expecting.

ds90uh929 comes with a default address of 0x0c (strapped). Idea is to override it with 0x0e. To achieve it, from the deserializer side, REMOTE_ID register is configured with address 0x0e and freeze bit as 1. But, serializer is not accessible after configuring the REMOTE_ID register.

Seems like I miss understanding of REMOTE_ID register. Can you please provide more details on how to configure serializer i2c address from deserializer side? Why the above method does not work? Any other approach to achieve the serializer i2c address configuration from deserializer side? Also details on REMOTE_ID register will help.

Best Regards,

Harsha

over 2 years ago

+1 Aaron Heng over 2 years ago

TI__Mastermind 31600 points

Hi Harsha,

The REMOTE_ID register is mainly used when you have the link and lock from serializer to the deserializer. This register will automatically loaded the value from the serializer side. For example, since you have the 929 set to 0x0C, this register will display on the 940 0x07 = 0x0C. Forcing or changing the value of this register will lost communication between the serializer and deserializer.

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

Aaron

0 Harsha Manjula Mallikarjun over 2 years ago in reply to Aaron Heng

Prodigy 10 points

HI Aaron,

Thank you very much for the fast feedback. The information was useful. On top of this I experimented a bit and following sequence gave me the result:

set up REMOTE_ID i2c address to a desired value along with freeze bit set to 1.
Enable I2c pass through (open up the gates). Remote device cannot appear on the bus with its default address because REMOTE_ID is set. Refer:
Configure Slave ID and Slave Alias registers to access the Remote device and set its I2C address. Now device becomes accessible with the new i2c address because of Slave Alias configuration.
Clear freeze bit in REMOTE_ID register. This reloads the I2c address from remote device (In step3 desired address is already configured).

Also conversation in the following thread helped:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/980276/ds90ub933-q1-i2c-pass-through-option?tisearch=e2e-sitesearch&keymatch=i2c%2520pass%2520through#

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DS90UH940-Q1: REMOTE_ID register configuration