Compiler/DS90UB947-Q1: DS90UB947 vs DS90UB948 I2C communicaiton

Hi Kim,

thank you to touch us.

May I know if you can access UB947/ub948's register?

To initiate the link between UB947/ub948, one option is that you can set the mode_sel based on d/s description (such as single OpenLDI or dual, etc.), the link between UB947 and UB948 can be run automatically without any other register settings.

Also, you can set the I2C pass-through mode to visit the remote I2C device, then you need set the reg. to enable the pass-through. To, to set the registers in details, please let's know how you use our UB947 and UB948. thanks.

best regards,

Steven

Hi Steven

Thanks for your kind reply.

We designed PCB circuit to use Single Ended Coaxial mode. (Please refer to the attached file for PCB circuit design)

Below is block diagram of my circuit design.

 " MCU => DS90UB948 = > DS90UB947 => I2C Device(Sony Image Sensor) "

DS90UB948 that receives data from DS90UB947 is "2-Lane FPD-Link III Input", "Single Link OpenLDI output".

Question 1 : If I can use I2C communication to control image sensor (I2C device) with Single Ended Coaxial mode?

Question 2 : If yes, please provide initial setting register code?

Question 3 : If there is something wrong in our PCB circuit design please let me know what we have to change?

947-948 schematics.pptx

Thanks and kind regards

Sam Kim

Kim,

Pls check the comments as below:

Question 1 : If I can use I2C communication to control image sensor (I2C device) with Single Ended Coaxial mode?

TI: yes it can.

Question 2 : If yes, please provide initial setting register code?

TI: please refer to app. note on I2C over FPD-Link, you can get how does it work and how to set it (pass-through and slave ID / Slave alias ID, etc.)

Question 3 : If there is something wrong in our PCB circuit design please let me know what we have to change?

TI: : pls follow up the d/s design on power-on sequence request, also the mode_sel pin setting is based on your system request, you can follow up the d/s design guide. regarding the sch., the UB948's C74/C80 can be replaced with 47nf capacitors.

Hi Junqiang Shi,

Thanks for your great help. 

You have been very much helpful to our development project.

I think that this would be my final question about this project.

We are using Sony's IMX273 image sensor.  It send out low voltage LVDS signal to DS90UB947 as below.

"IMX273 => DS90UB947 => DS90UB948"

When we first start to develop our system we thought that Sony IMX273(LVDS) is competitable to DS90UB947 (Open LDI).

However, we started to think it may be not competitable. I attached Sony IMX273's LVDS spec..

Please see and let me know if Sony IMX273(LVDS) is competitable to DS90UB947 (Open LDI).

Thanks in advance.Sony IMX273 LVDS Specification.pptx 

Hello Sangwok,

The LVDS format from IMX273 is not compatible with 947 (Open LDI). OpenLDI uses a clock which is 1/7 the frequency of the data lines but the IMX273 looks like it uses a clock with the same frequency as the data (subLVDS).

Best Regards,

Casey