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DS90UB947-Q1EVM: GPIO issue in 18-bit video mode

user4289837
Intellectual 435 points
Part Number: DS90UB947-Q1EVM
Other Parts Discussed in Thread: DS90UB948-Q1EVM

Hello

I'm using DS90UB947-Q1EVM and DS90UB948-Q1EVM. normally, The DS90UB948 GPIO0-3 can be remotely controlled by DS90UB947  GPIO0-3. But when I set the DS90UB947 to 18-bit video mode by register '0x12 Data Path Control'. The DS90UB948 GPIO0-3 will no be able to remotely controlled by DS90UB947  GPIO0-3 which I have set as input mode. by the way ,change 947 to 941 will get the same issue. is there any problem？

Nick Li

  • 0
    TI__Guru** 103215 points

    Hello Nick,

    Are you programming anything else to the device besides register 0x12? Also are you using single channel or dual channel mode between 947 and 948?

    Best Regards,
    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 435 points

    Hello Casey

    I'm using dual channel between 947 and 948

    After powerup , I set Serializer 0x0F[3:0] = 0x3,Deserializer 0x1F[3:0] = 0x5, the GPIO remote control is OK. then I set 0x12 as 0x04(Select 18-bit video mode),nothing else. after this , the GPIO remote control  doesn't work anymore.

    Best Regards,
    Nick Li

  • 0 in reply to user4289837
    TI__Mastermind 37220 points

    Hi Nick,

    I will double check your setting and get back with you.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Mastermind 37220 points

    Hi Nick,

    Just want to let you that I was able to find the 947EVM. I will try them out based on your steps to see if I can replicate your issue. Afterward, i will provide you more detail how to implement this.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Mastermind 37220 points

    Hi Nick,

    I tried the same setting per your comment in this thread. I was able to get it working with remote controlled.

    Please see attached short video.

    Aaron

  • 0 in reply to Aaron Heng
    Intellectual 435 points

    Hello, Aaron

    Thank you very much, but there is a little difference between our experiments. 

    Please see attached short video , Thanks

    Nick Li

  • 0 in reply to user4289837
    TI__Mastermind 37220 points

    Hi Nick,

    Thank you for sharing the video. I will try it out once I have a chance to go back to the lab again. I am planning to go there maybe this Friday.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Mastermind 37220 points

    Hi Nick,

    Just want to inform you that I was able to replicate your issue on my setup. I am still looking at this, and I will inform once I know what is the root cause.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Mastermind 37220 points

    Hi Nick,

    Just want to provide you the progress in finding the issue. I tried GPIO0 -> 3; they are all pulled to LOW when I enabled the 18-bit video mode. I need more further investigation.  I will provide you updates once I got the information.

    Aaron

  • 0 in reply to Aaron Heng
    Intellectual 435 points

    Hello, Aaron

    I got it ,Thank you.

    Nick Li

  • 0 in reply to user4289837
    TI__Mastermind 37220 points

    Hi Nick,

    Just to let you know that I am still looking at this issue. Tomorrow, I will have lab time, and I will get the registers dump to review in detail.

    Aaron

  • 0 in reply to user4289837
    TI__Mastermind 37220 points

    Hi Nick,

    Just want to inform you that I am getting close to resolve the issue. I will try something tomorrow on the setup, and provide you the instruction how to fix this.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Mastermind 37220 points

    Hi Nick,

    I apologize for the long delay. I was able to test GPIOx findings. The reason you are seeing the GPIOx goes LOW when you enable the 18-bit video register 0x12[2] of the 947 is because the 948 is pulling GPIO3 LOW. If you review the 926 or 928 datasheet, the GPIOx works only in 18-bit mode. In order to prevent this happening triggers the GPIOx to LOW, you need to force deserializer 948 capability on 947. This will configure the 947 to send GPIO as if it was talking to the 926 which does not support GPIOs in 24-bit mode.

    Could you please provide me the device revision by reading the following register?

    • On 947, read register 0x0D the MSB nibble will determine the device revision.
    • On 948, accessing to the remote register tab, go to register 0x1D.

    Here is the instruction how to bring up the GPIO3 in FWD channel.

    1. Configure GPIO3 as input by setting register 0x0F[2:0] = 0x3 for 947.
    2. Configure GPIO3 as output by setting register 0x1F = 0x5 for 948.
    3. Apply 1.8V input to GPIO3 on 947.
    4. Set 947 18-bit video mode on register 0x12 = 0x04. This should be automatically loaded into the deserializer side. Once you enabled the register 0x12, GPIO3 immediately goes LOW. To this check, you can access to the 948 register 0x22[2].
    5. Forcing deserializer capabilities in 947 by programming the register 0x20 = 0x8A.
    6. Now, on 948 register 0x28[5] is set to video disabled. In order to clear this bit, you set the RX Lock mode.
    7. On 948 register 0x34, you can set register 0x34[6]. Now, GPIO3 is back up to HIGH.

    Hope this helps. Please click resolve if you think resolution to the issue. Let me know if you have any other questions.

    Aaron

  • 0 in reply to Aaron Heng
    Intellectual 435 points

    Hello, Aaron

    GPIO3 works correctly  according this steps. Thanks very much.

    • On 947, revision ID is 0001 in 0x0D;
    • On 948, revision ID is 0001 in 0x1D

    Best regards

    Nick Li