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AFE7950: fspi, spia, spib, spib2

Yoonsun Kim
Expert 1860 points
Part Number: AFE7950


Hi,

There are many SPI port on afe7950.

1> FSPI

Can I use FSPI for setting someting default value?

2> spia, spib, spib2

Is there any reason why there are three spi port?

When I tested EVM by Latte, the bringup(AFE.deviceBringup()) took quite long time. If I use only SPIA via 20MHz spi clock by FPGA, how long does it take for normal setting such as AFE79xx_EVM_Mode8.py?

Regards,

  • +1
    TI__Mastermind 18031 points

    Hi Yoonsun,

    The FSPI is not available to be used for programming. The FSPI is for factory use only and is available to you as a generic GPIO. 

    The AFE7950 includes three SPI interfaces (SPIA, SPIB1, SPIB2) that have identical functions. The reason for having all three is that in some applications the auxiliary SPIs, SPIB1 and SPIB2, are required to access separate registers. One thing to note is that on reset the SPIA is the only port enabled and the two auxiliary ports have to be enabled through SPIA.

    The reason for the long bringup time with Latte is because of the slow USB connection, software overhead, and file logging. By default Latte is logging all of the writes required in order to program the AFE and this increases the bringup time. To disable the logging you can set the following parameter to 0: logDumpInst.logFormat = 0x00 (Line 131 in the Mode8 script). 

    If a FPGA is used to program the AFE using SPIA the bringup time would be about 6 seconds. The reason for this amount of time is that the SERDES receive adaptation can take up to 5 seconds.


    Regards,

    David Chaparro