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DS90UB947-Q1: How many GPIOs can be used for bidirectional control signal?

Ansel Song
Expert 3890 points
Part Number: DS90UB947-Q1

Hi team,

I have several questions about GPIOs of 947:

1. How many GPIOs can be used for bidirectional control signal?  (GPIO0-GPIO3,  D_GPIO0-D_GPIO3 ? )

2. Does the use of D_GPIO only need to be used under dual link mode? Does it have anything to do with the number of DSI connected to the input (eg. DSI inputs only D0-D3 connected ).

3. Can the usage of D_GIPO be equivalent to general GPIO in dual link mode? Except for faster speed.

Thanks for your patient to reply for these question.

Best regards,

Ansel Song

  • 0
    TI__Genius 12866 points

    Hi Ansel,

    1. It depends on how many FPD-Link channels are connected. If only one channel is connected, you can use GPIO0-3 only. If both ports are connected, you can use both GPIO0-3 and D_GPIO0-3.

    2. It has nothing to do with DSI lanes. Use of D_GPIO only depends on FPD-Link mode.

    3. Yes.

    Best Regards,

    Charley Cai

  • 0 in reply to Charley Cai
    TI__Expert 3890 points

    Hi Charley,

    As we know, I2S_CLK,  I2S_WC and I2S_DA  are shared with GPIO8_REG, GPIO7_REG, and GPIO6_REG,  accordingly.

    Based on the this application note (http://www.ti.com/lit/an/snla234/snla234.pdf) , these pins can also be configured with GIPOs  for control signals.

    In fact, I have done similar experiments on 92X EVMs. It seems that I2S can be configured as GPIOs to achieve bidirectional control.

    Best regards,

    Ansel Song

  • 0 in reply to Ansel Song
    TI__Genius 12866 points

    Hi Ansel,

    These pins work a little differently comparing to normal GPIOs even in I2S mode.

    I2S_CLK can be used for data lower than 13MHz for 947.

    To use I2S_WC and I2S_DA, a clock signal has to be supplied to I2S_CLK and they will be sampled by I2S_CLK instead of PCLK.

    If you are looking for extra pins to send slow control signals and you don't intent to use I2S, these pins could be used.

    Best Regards,

    Charley Cai

  • 0 in reply to Charley Cai
    TI__Expert 3890 points

    Hi Charley,

    These Pins work in GPIOs mode, can they be transmitted in both directions?

    Best regards,

    Ansel Song

  • 0 in reply to Ansel Song
    TI__Genius 12866 points

    Hi Ansel,

    The GPIO mode pins can be transmitted in both directions.

    Best Regards,

    Charley Cai

  • 0 in reply to Charley Cai
    TI__Expert 3890 points

    Hi  Charley,

    In fact, we have been discussing whether GPIO_REG (I2S) is configured as a GPIO to enable bidirectional transmission.

    However, as shown in the datasheet, GPIO_REG can only be used as Local and not bidirectional transmission. But as the Application note we discussed earlier, GPIO_REG can also be configured as GIPO for bidirectional transmission. So I want to confirm which of the datasheet and APP note is correct?


    In addition, I also tested it on the 947-948 EVM board, and GPIO_REG can also realize bidirectional transmission.

    Best regards,

    Ansel

  • 0 in reply to Ansel Song
    TI__Genius 12866 points

    Hi Ansel,

    These GPIO_REG pins are shared with I2S pins. The bidirectional transmission is realized through the I2S functionality.

    The methods and limitations of using these pins as GPIOs are documented in the app note.

    If you would like to use them as GPIO, you can follow the App note.

    Best Regards,

    Charley Cai