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DS90UB949A-Q1EVM: Ds90ub949EVM J25 I2C can only read but not write

xinyu wu
Prodigy 115 points
Part Number: DS90UB949A-Q1EVM
Other Parts Discussed in Thread: DS90UB949A-Q1

Dear TI,

I have an urgent problem that needs your help.

We want to use the development board to connect I2C to control ds90ub949 EVM.

But the problem now is that I connect J25 I2C with DuPont cable i2c_scl, i2c_sda and GND, and read and write EVM registers on the SOC side.

It is normal to read the register data and the data is correct, but when I write to the EVM register, it is unsuccessful.

When I write the data to the register, the register data is still the same value. Could you help me?

Thank you.

Wu.

  • 0
    TI__Guru** 108090 points

    Hello Wu,

    for I2C communications you should use J20 header.

  • 0 in reply to xinyu wu
    TI__Guru** 108090 points

    Hello Wu,

    yes, you are right! I was looking into the UB949 EVM, but you are using the UB949A EVM.

    I will look into this and come back to you shortly!

  • 0 in reply to Hamzeh Jaradat
    Prodigy 115 points

    Hi Jaradat,

    Thank you very much for your help and reply. Now I can connect I2C directly to J25 and can read and write 949a registers. But now I have another question: can you help me analyze it? I can now communicate with I2C's screen side deserializer. I want to control the backlight device on the screen side through the I2C on the SOC side. Now I can read the value of the I2C device register on the screen, but I can't modify its value. Is it because my configuration is incorrect?

    The actual I2C address of my backlight device is 0x30. I have made the following settings:
    1. Set ser register: 0x07=0x60; Set 0x08=0x62;
    2. Set derer (i2c:0x2c) set register 0x08=0x60; Set 0x10=0x62
    3. Communicate with the backlight device through the virtual address of 0x31 backlight device. But the problem is that you can only read from the backlight device, but you can't write.
    Is it because I have some problems with the configuration of serializer and deserializer? Can you check it for me?

    Wish you a happy life，

    Wu

  • 0 in reply to xinyu wu
    Prodigy 115 points

    Hello, jaradat,

    My reply above may not be clear, please allow me to reply one more.


    Thank you very much for your help and reply. Now I can connect I2C directly to J25 and read and write 949a register. But now I have another question: can you help me analyze it? I can now communicate with I2C's screen side deserializer. I want to control the backlight device on the screen side through I2C on the SOC side. Now I can read the value of the backlight device register through I2C on the SOC side, but I cannot modify its value. Is it because my configuration is incorrect?
    The actual I2C address of my backlight device is 0x30. I made the following settings:
    1. Set ser register: 0x07=0x60; Set 0x08=0x62;
    2. Set der (i2c:0x2c) set register 0x08=0x60 set 0x10=0x62
    3. Communicate with the backlight device through the virtual address of 0x31 backlight device. But the problem is that I can only read from the backlight device, but I can't write.
    Is it because I have some problems with the configuration of serializer and deserializer? Can you check it for me?
    I wish you a happy life,
    Wu

  • 0 in reply to xinyu wu
    TI__Guru** 108090 points

    Hello Wu,

    Glad that you can Read and Write now.

    To understand your system better, do you have a block diagram showing your system and where are you communicating?

    I understood that your system looks like this:

    Your I2C interface ==> UB949A ==> STP Cable ==> UB94x DES ==> SoC ==> Backlight device.

    Is the above correct?

  • 0 in reply to Hamzeh Jaradat
    Prodigy 115 points

    Hi Jaradat，

    No, it's a little different. My hardware link diagram is like this:
    My I2C interface ==> UB949A ==> STP Cable ==> UB948 DES ==> MCU ==> Backlight device.

    Please check it, thank you.

    Wu

  • 0 in reply to xinyu wu
    TI__Guru** 108090 points

    Hello Wu,

    you do not need to define any Slave ID or Slave Alias on the DES reg 0x08 and 0x10. These are required if the slave is connected on the SER side. But in your case the Slave is connected on the DES hence these are not required.

    From our devices there is no other settings are required than setting reg 0x07 and 0x08 on the SER.

    You need to check the settings of the MCU or the Back Light controller itself if it is allowing remote writes or it is blocked!

  • 0 in reply to Hamzeh Jaradat
    Prodigy 115 points

    Hi Jaradat ,

    Thank you very much for your reply, I will confirm the above information。 I also want to ask about my display parameters, which are different from the standard 1920 × 1080 display resolution is somewhat different.
    So I want to confirm with you: do I need to brush EDID based on this parameter into EVM board again. If necessary, can you help me provide the EDID of this parameter? Thank you very much

    Wu

  • +1 in reply to xinyu wu
    Prodigy 115 points

    Thank you very much for your reply, I will confirm the above information。
    I also want to ask about my display parameters, which are different from the standard 1920 × 1080 display resolution is somewhat different. So I want to confirm with you: do I need to brush EDID based on this parameter into EVM board again.
    If necessary, can you help me provide the EDID of this parameter? Thank you very much

  • 0 in reply to xinyu wu
    TI__Guru** 108090 points

    Hello Wu,

    it is preferred to seperate threads to one topic which matches the title. Hence, please create new thread with new title and the new questions.