DS90UB954-Q1EVM: I2C Communication stops when J16 VDDIO set to VDD3V3 3.3V

Prodigy 20 points

Replies: 3

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Part Number: DS90UB954-Q1EVM


I have a DS90UB954-Q1EVM board communicating with a 953 serializer in a camera, connected through a Fakra connector to J29.  The device is locked.

The DS90UB954-Q1EVM board appears to stop communicating with ALPS when the J16 VDDIO voltage select jumper is set to VDD3V3 3.3V.

The user guide indicates Pin 1-2 are shorted together to use 3.3V as the default, but my device was received with pins 2-3 connected, to use 1.8V.

At 1.8V, ALPS correctly identifies the connected serializer as a 953 and locked.  If the jumper is moved, the app hangs until the 1.8vio is restored.

If the app is started with the jumper set to 3.3V, it identifies the serializer as 913, and not locked, despite the lock LED D9 glowing.

I would like to use J25 to connect to I2c using 3.3V instead of 1.8V.   Other EVMs work at 3.3V i2c.

J25 is not currently connected to any external device.

I have consulted hsdc007_reva_evm.pdf for the updated schematic with the wiring of I2C connector J25 (opposite of Table 6) and J16.

Thank you,


3 Replies

  • Hello J,

    Could you please confirm the version of ALP you are using? Just want to be sure you are using the latest version. Also, could you make sure you have downloaded the latest ALP-PROFILE-UPDATE and applied it. TI releases ALP profile updates with new features and bug fixes. You can test if you have the latest profile update installed by checking Help--> About this program.

    I think all the board jumper settings might have to be checked. Could you please upload a photo of the board jumper and switch settings?



  • In reply to Vishy Viswanathan:

    Hello, Vishy.

    The ALPS version is 1.057.0010 the latest version available this week, with the updates.

    I have scoped the i2c pins and what is happening is that when my camera is attached it attempts to function for 2 i2c word transmissions, at 3.3v Then the scl becomes corrupted, as if there is a voltage limiting component, and goes to a constant high frequency 5.5mhz 0~2.5v corrupted scl trying to clear the bus.  SDA stays high at 3.3v. If the camera is then disconnected the 5.5mhz scl remains.  The only thing that stops the 5.5mhz scl is removing the vddio jumper J16.  Scl does not get corrupted if the camera is not attached... but that situation is not useful.  I have also tried a different camera that functions with the 934evm, and it also has the same results.

    The Scope displays the corrupted scl at 1v,100ns/div.



  • In reply to J Guy:

    Hello J,

    Thanks for the picture and the screen shots. Let me experiment on Monday and get back to you.