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DS90UB948-Q1EVM: GPIO settings are forgotten after power cycle

Simon von Riegen
Prodigy 20 points
Part Number: DS90UB948-Q1EVM
Other Parts Discussed in Thread: DS90UB947-Q1EVM

Hi TI,

 

we configured the DS90UB948-Q1EVM GPIOs (1-4) to remote control by using the tunneled i2c bus from the serializer side. We use these GPIOs to pass through the Backlight PWM and Enable signal for the LVDS-display. The problem is that the remote GPIO settings are forgotten after a power cycle of the deserializer as they are not shared between serializer and deserializer. (You need to directly set the registers on both sides.) Other parameters are reloaded after the link between the serializer and deserializer is reestablished.

We are aware that we could poll the link status register to detect a link loss and wait for the link to return to reconfigure we deserialzer again but that seems a little wasteful.

Are there any settings or solutions that the DS90UB948-Q1EVM to get these information retransmitted from the serializer after the link returns, like the other settings ?

Without this the PWM and Enable signales are getting lost and the display stays dark as the backlight isn’t switch on again. The mission would be Plug&Play between the computer+serializer and the deserializer/display.

Best Regards

Simon

  • 0
    TI__Mastermind 22946 points

    Hi Simon,

    I need to look into this and will get back to you by the end of today.

    Best,

    Josh

  • 0
    TI__Mastermind 22946 points

    Hi Simon,

    What is the serializer being used? Could you check the power sequence meets with our recommended power sequence? The GPIO setting has to be set after power is applied. Also, please check Lock status is stable while PDB is on because Lock status might effect on GPIO. Can you provide reg dumps from serializer and 948? In the meantime, please refer to GPIO[3:0] and D_GPIO[3:0] Configuration table and . GPIO_REG and GPIO Local Enable and Configuration table of the datasheet.

    Best,

    Josh

  • 0 in reply to Josh Baik
    Prodigy 20 points

    Hi Josh,

    the serializer being used is the DS90UB947-Q1EVM . I can establish a working link between the serializer and deserializer after powering up both simoustanly. The GPIO[3:0] are working after configuration of the registers. The problem I have is after a powering down and powering up only the deserializer side. The configurations of the GPIO registers are lost. The video link and the I2C connection are automatically restored and and I can see the video and use the connected touch screen via I2C. My question was is there a function to restor the GPIO settings after a power down and power up sequenz automatically or do I have to reconfigure these setting by hand every time after a power cycle?

    Best,

    Simon

  • +1 in reply to Simon von Riegen
    TI__Mastermind 22946 points

    Hi Simon,

    Thank you for the clarification. We don't have the feature to automatically recover the setting. When PDB = L, then the device is powered off anyway, so the GPIO setting returns to a low value when disconnecting.

    Best,

    Josh