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DS90UB921-Q1: How to pass the input signal from DS90UB921-Q1 to DS90UB948-Q1 ?

Went Cao
Genius 5550 points
Part Number: DS90UB921-Q1
Other Parts Discussed in Thread: DS90UB948-Q1

Hi, all

      In my designed, the DS90UB921-Q1 support to RGB888, so that GPIO[0:3] can be used to GPI for input signal. and the GPO_REG[4:7] are output. how can I pass the input signal from DS90UB921-Q1 ?

     May I use the  blew ideas ? 

     1. Use the I2S_DA and I2S_WC to pass the input signal ?

     2. Use I2C of the DS90UB948-Q1 to set GPIO[0:3] of DS90UB948-Q1, so that I2C control GPIO[0:3] of DS90UB948-Q1 output ? 

  • 0
    TI__Mastermind 30515 points
    1. what is the paired with UB921? please see UB921 d/s, GPIO[3:0] pins are reused with RGB pins, they can't be used for remote control. For GPIO_REG[4:7] pins, they are used for local GPIO only. If you want to use this pins to transmit the control signals to the other side, you can make this work in I2S mode. The d/s also told how to use the I2S mode, please note the I2S_CLK should be among 1MHz and 10MHz.
    2. for reg. setting of UB948's GPIO status, you can read/write the GPIO status either 0 or 1. please check d/s example description on GPIO local control.

    best regards,
    Steven
  • 0 in reply to Steven(Shenzhen) Shi
    Genius 5550 points
    Hi,Steven

    2. Please show me which number of page said it ? I can find.
  • 0 in reply to Went Cao
    TI__Mastermind 30515 points
    pls read the section 8.3.9 on GPIO description.
    also, please let's know the improvement on UB948 d/s if you have questions to read it.
    in www.ti.com/fpd-link, we have on-line video on FPD-Link GPIO training, you can refer to it as well. thanks.


    regards,
    Steven
  • 0 in reply to Steven(Shenzhen) Shi
    Genius 5550 points
    Dear Steven
    1. ". If you want to use this pins to transmit the control signals to the other side, you can make this work in I2S mode. The d/s also told how to use the I2S mode, please note the I2S_CLK should be among 1MHz and 10MHz."
    question: your meaning is that set I2S mode,and give a 1MHz~10Mhz single to I2S_CLK pin, so that can use I2S_DA and I2S_WC to pass the signal ?
  • 0 in reply to Went Cao
    Genius 5550 points

    Dear Steven

         I find a document which is <Enabling GPIOs in the DS90UB925 and DS90UB926.pdf>, link:www.ti.com.cn/.../snla234.pdf
         In the document,"1.3.1 Using I2S_CLK as a GPIO",said I2S_CLK pin can be as the Backlight_PWM.
        My question :
        1. The I2S_CLK pin of DS90UB921-Q1 can be as the PWM?
         2. Can the I2S_CLK support to 200Hz ~ 20KHz PWM ?

  • 0 in reply to Went Cao
    TI__Mastermind 30515 points

    Please follow up TI's d/s request. when use I2S_CLK as remote control, please follow up the I2S application request.

    regards,

    Steven

  • 0 in reply to Steven(Shenzhen) Shi
    Genius 5550 points

    Dear Steven

          From TI’s datasheet of DS90UB921-Q1, I can't find paragraph about I2S_CLK as remote control. Could you show me ? Thanks a lot.

  • 0 in reply to Went Cao
    TI__Mastermind 30515 points
    Yes, it has no name for i2s remote control. here we just re-use the I2S communication channel between UB921 and its de-ser, but the signal is NOT audio but what you are transmitting the "control signal".

    regards,
    Steven
  • 0 in reply to Steven(Shenzhen) Shi
    Genius 5550 points
    Dear Steven
    In your opinion,I2S_CLK can transmitting the PWM signal. But you said I must follow up the I2S application request.I fully read the datasheet,but only find "7.3.16 I2S Transmitting",it show that there are some Audio Interface Frequencies, so it support these frequencies like "Table 4. Audio Interface Frequencies" ? Can't support to 200Hz ~20KHz ?
  • 0 in reply to Went Cao
    TI__Mastermind 30515 points
    in UB921 d/s, the i2s data rate is listed in table4. when it is paired with UB948, pls check UB948's d/s, it limits the I2S_CLK to be >=1MHz. so to transmit the low freq. PWM signal, you can use I2S_DA/WC pins meanwhile please send one 1MHz clock to I2S_CLK. In this mode, you just take the PWM signal as audio signal and transmit it from UB921 to UB948's I2S pins.

    regards,
    Steven

    Note: pins reused by UB921 as below
    I2S_CLK can optionally be used as GPO_REG8, I2S_WC can optionally be used as
    GPO_REG7, and I2S_DA can optionally be used as GPO_REG6.