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DS90UB949-Q1: PWM pass through and map the GPIO

Zirui Su
Expert 5340 points

Part Number: DS90UB949-Q1

Hi team

We want to pass thorough a channel of GPIO multiplexed as PWM from the host to the screen to drive the backlight, but the host serializer 949 hardware is connected to GPIO2, and the front screen 948 is connected to GPIO3. I would like to ask:

1. Could we pass through PWM signal though GPIO on SER and DES?

2. Is there any method you can map 949 GPIO2 to 948 GPIO3?

Thank you. 

  • 0
    TI__Mastermind 41730 points

    Hi Zirui,

    Yes. 94x can be used to send the PWM signal via GPIO. You would need to oversampling GPIO fwd direction. Unfortunately, you can't re-map the GPIO to a different GPIO. It must be 1:1, GPIO0-0, GPIO1-1, etc..

    Aaron

  • 0 in reply to Aaron Heng
    TI__Genius 11690 points

    Hi Aaron,

    Our customer has the similar requirement for this GPIO pass through function, can you kindly help to show us some example configuration script for UB949 side and UB948 side how to enable this function? Thanks a lot!

  • 0 in reply to Jacky Wang(QD)
    TI__Mastermind 41730 points

    Hi Jacky,

    I am not sure what is going on with this thread. It wasn't routed back to me. Sorry this drop off on my radar. Are you trying to pass the GPIO FC? Do you have any specific GPIO that you want to send through the link?

    Aaron

  • 0 in reply to Aaron Heng
    TI__Genius 11690 points

    Hi Aaron,

    Customer's hardware configuration is PWM input->I2S_DD/GPIO3(UB949) ===FPD-Link=== I2S_DD/GPIO3(UB948)->PWM output, block diagram refers to below. Thanks.

  • 0 in reply to Jacky Wang(QD)
    TI__Mastermind 41730 points

    Hi Jacky,

    Thanks for the providing the information. I will provide you the instruction by Tuesday, 10/12.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Mastermind 41730 points

    Hi Jacky,

    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 949.
    2. Configure GPIO3 as output by setting register 0x1F = 0x5 for 948.
    3. Apply PWM input signal to GPIO3 on 947.
    4. Set 947 desired video mode 18-bit or 24-bit on register 0x12. 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, you should be able to monitor PWM signal.

    Hope this helps. Let me know if you have any questions.

    Aaron