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DS90UB926QSEVB: DS90UB926 or DS90UB925 ,which is suitable for ?

Intellectual 640 points

Replies: 10

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Part Number: DS90UB926QSEVB

Hi :

Function Description:
In the figure above, video equipment is a video output device and display equipment is a video receiving device. Now we need to make a device to collect video data between video and display. According to this function, figure 1 and Figure 2 in the figure above are designed. The main functions of the two schemes are as follows:
Receive a fpdlink III signal, assign this signal to an external port, and collect the received fpdlink III signal into FPGA. FPGA needs to complete the data conversion from RGB to YUV422, and then convert the YUV422 data to Mipi csi2 signal output through a chip.

According to the function, there are two schemes, figure 1 and Figure 2. But now there are several problems as follows:
1. Using Figure 1 scheme, please recommend which model of Ti chip meets some functions of "which chip". (this scheme is preferred)
2. Figrue2 scheme is adopted, and 926 and 925 are configured as repeater mode. How to configure I2C registers of these two chips Since the whole video has been transmitted through 926 and 925, the transmission process is 925 - > 926 - > 925 - > 926. The whole design purpose is to collect data transparently. What's a good processing method for I2C?

  • Hello Jerry,

    Figure 2 is much more feasible for the function you are trying to achieve. The I2C can be set up to pass through the first 926 using the "slave address" and "slave alias" registers. That way the middle point looks transparent to the source. See registers 0x08-0x17 for configuration of slave addresses and aliases. You can also take a look at this app note on I2C addressing for FPD-Link. The same concepts here apply for 926/925: http://www.ti.com/lit/an/snla222/snla222.pdf

    What is the PCLK rate for this system? One thing you will need to be extra careful about is the high speed connections for the RGB fanout from 926. You must take extra care to ensure stubs are minimized on the RGB pin outputs going to two sink devices, otherwise the SI may be degraded. 

    Best Regards,

    Casey 

  • In reply to Casey McCrea:

    Hello Casey,

    The transmission process is A( 925) - >B( 926) - >C( 925) - >D( 926). Which chip is selected to configure the "slave address" and "slave alias" registers?   A or B or C or D ?

  • In reply to user313175:

    Hello Casey,

    The resolution of  pixel  is 1280 x 1024 and the frame rate is 60 HZ。

  • In reply to user313175:

    Hi Jerry,

    The Slave ID will be associated with the second 925, allowing I2C to pass through from the SOC attached to the first 926 on the input (not displayed), over the FPD-Link III connection and out I2C from the first 926 to the second 925.

    When configuring the first 925 (not pictured) that is attached to the input, the remote id will be that of the first 926 and the slave id will be that of the second 925.

    Sincerely,
    Bryan Kahler

  • In reply to Bryan Kahler:

    Hello Bryan,

    The transmission process is A( 925) - >B( 926) - >C( 925) - >D( 926). But A and D is not my equipment. As you said,How can I implement this function? The figure 1 suits me better.

  • In reply to user313175:

    Hi Jerry,

    If you're tied into the local i2c on the first 926 pictured:

    In that case, you won't need to use the slave, just the remote.  pictured 926 to 925.  If you have a device you'd like to connect to i2c on the 925, that could then be given a slaveID or alternatively pass-through i2c enabled.

    Sincerely,
    Bryan Kahler

  • In reply to Bryan Kahler:

    Hi Jerry,

    Just want to add here, the latest comment above is for initial device bring up assuming static settings, when you don't control the initial 925 or 926, but the initial bring up of both devices is known and static.  An additional MCU may be required if passthrough and slave isn't configured based on the strap settings.

    If the system is going to be dynamic or requires additional configuration of the deserializer beyond the mode and strap settings, please give additional information about the system it will be tied into.

    Sincerely,
    Bryan Kahler

  • In reply to Bryan Kahler:

    Hi Bryan,

         That is to say, as long as I configure the first 926(B)  and the second  925(C) as pass-through mode, I do not need to configure 926 and 925 through I2C?

  • In reply to user313175:

    Hi Jerry,

    Going to use a crude ascii art representation here for the description:

    (1) <-- FPDIII--> (2) <==IMG==> (3) <---FPDIII--> (4)
                       ^             ^
                       |_____________|
                              |
                              v
                             MCU
    

    (1) and (4) are the original serializer and deserializers that are not in your control.

    (2) and (3) are the deserializer and serializer that will be used

    1) MCU is connected to the I2C bus with (2) and (3) and will be used to configure (2) and (3)

    2) MCU will bring up (3) and determine the I2C address of (4) and configure (3).

    3) MCU will bring up (2) and ensure the address of (2) is not the same as (4) or (3).  

    4) MCU will enable I2C pass through on (3) and (2).

    Please let me know if there are any questions.

    Sincerely,
    Bryan Kahler

  • In reply to Bryan Kahler:

    Hi Bryan,

    You reply is very clearly.

    Thank you.

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