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DS90UB941AS-Q1: questions about 941/926&948

Betty Guo
Expert 7300 points
Part Number: DS90UB941AS-Q1

Hi expert,

customer use 941 connect two display, one use 926(480*240); one use 948(1920*720,dual LVDS), below is simply diagram:

we have below questions need your help:

1. I2S configuration. In this case, 948 need I2S while 926 needn't, so how to configure 941 side?

2. SPI configuration. 948 need SPI while 926 needn't , how to configure 941?

3. both 948 and 926 need INT signal,but 941 only have one REM_INT, how to assign INT in 941? is there need external GPIO singal as INT?

4. they set the back channel frequency of 926 to 5M and set 948 to 20M, Is there a conflict in 941 side?

5. because only one lane DSI input on 941, Is it only necessary to connect the REFCLK0 crystal oscillator, and REFCLK1 does not need to be connected?

6. for unused DSI of 941, how to configure the unused pin? Connect ground or left, which one is recommended ? customer care about power consuption if they connect to ground.

7. Since 941 connect two Deser,  if customer want tansfer GPIO like PWM from 941 to 926, how to specify the GPIO is transfer to 926 rather than 948?

8. below output connector, customer would like use 1/3 tansmite 3.3V/5V switch signal, they have concern that if this will affact Dout signal quality.

Thanks in advance.

  • 0
    TI__Mastermind 30515 points

    pls check below comments:

    1.  I2S configuration. In this case, 948 need I2S while 926 needn't, so how to configure 941 side?

    TI: you can refer to d/s on slit audio description. 

    2. SPI configuration. 948 need SPI while 926 needn't , how to configure 941?

    TI: can't support it directly if you need both spi and i2s.

    3. both 948 and 926 need INT signal,but 941 only have one REM_INT, how to assign INT in 941? is there need external GPIO singal as INT?

    TI:you can check 941as d/s reg. 0x30 (0001: REM_INTB indicates port 0 remote interrupt, INTB indicates port 1 remote interrupt)

    4. they set the back channel frequency of 926 to 5M and set 948 to 20M, Is there a conflict in 941 side?

    TI: it is ok.

    5. because only one lane DSI input on 941, Is it only necessary to connect the REFCLK0 crystal oscillator, and REFCLK1 does not need to be connected?

    TI：REFCLK0/1 is optional for fpd link0 and fpd-link1. but generally you can use DSI clock for FPD-Link so it is not must.

    6. for unused DSI of 941, how to configure the unused pin? Connect ground or left, which one is recommended ? customer care about power consuption if they connect to ground.

    TI: leave it open

    7. Since 941 connect two Deser,  if customer want tansfer GPIO like PWM from 941 to 926, how to specify the GPIO is transfer to 926 rather than 948?

    TI: GPIO0-3 of 941as is mapped to port0's deser's GPIO0-3, DGPIO0-3 of 941as is mapped to port1's deser's gpio0-3.

    8. below output connector, customer would like use 1/3 tansmite 3.3V/5V switch signal, they have concern that if this will affact Dout signal quality.

    TI: it is not clear picture. generally you can use signal + supply in the STQ cable.

  • 0 in reply to Steven(Shenzhen) Shi
    TI__Expert 7300 points

    Many thanks Shiqiang.

    just to confirm below:

    1. for split audio in datasheet, my understanding is set SPLIT_AUIDO to 0, set I2S_TRANSPORT_SEL to 1 and disable Channel B, right?

    2. you meand 948 can't receive the SPI and I2S at the same time? why?

  • 0 in reply to Betty Guo
    TI__Mastermind 30515 points

    just as described in d/s, I2S_TRANSPORT_SEL is used to how to send audio through FPD-Link: 1: Enable I2S Data Forward Channel Frame Transport 0: Enable I2S Data Island Transport. SPLIT_AUDIO is used to how to transmit audio in port0 and port1: If SPLIT_AUDIO is set to 0, the same audio will be sent on each port. The number of channels sent will depend on the DATAPATH_CTL register settings. Both ports will be configured the same. If SPLIT_AUDIO is set to 1, the upper and lower channels will be swapped for port 1. This is done by swapping the I2S signals for I2S_A/B with I2S_C/D. In stereo mode, this will result in the I2S data on channel C being sent on port 1.

    when 948 is used in dual fpd-link channel, it can receive both spi and i2s simutaneously.

    regards,

    Steven