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AFE7950: Hardware design is FPGA+LMK04828+AFE7950. Here are some of my questions.

Yake Li
Prodigy 100 points
Part Number: AFE7950
Other Parts Discussed in Thread: LMK04828,

Our hardware design is FPGA+LMK04828+AFE7950.  The spi interface of the LMK chip and AFE chip is directly connected to the FPGA, without connecting to the PC through USB.

Here are some of my questions:

1. I have modified some functions in baseFunc.c.  But how can I modify the function giveSingleSysrefPulse?  Is the sysRef here a hardware pin? Our hardware design is now connected to LMK.

2.  We have noticed that on the LATTE software interface, there are tx/rx/fb channels that can be opened or closed.  But AFE also has 6 hardware pins used to control TX EN, RX EN, and FB EN. Is there any conflict if both software and hardware control the channel simultaneously?

3. What are the functions of these two: ti_afe79_overrideTdd、ti_afe79_overrideTddPins  ? Are these two related to my second question?

  • 0
    TI__Genius 14270 points

    Hi Yake,

    1. The giveSingleSyrefPulse function should write to the LMK SPI and request a SYSREF pulse. This is only required when the AFE is configured for pulsed or single shot SYSREF. If the AFE is configured for continuous SYSREF then this function is not needed as the SYSREF should already be running, from the LMK, before the AFE bringup. 

    2. In Latte we configure the 6 GPIO pins to be for TDD. The pins will control whether the ADC/DAC is in Active Mode or Standby Mode, power saving mode. Putting a channel into Standby mode can also be done using SPI writes. To do this you must first enable overriding the TDD pins, previously defined in the Latte script, then you can set the state of the overridden TDD pin. 

    3. The function two functions that you show are used for controlling whether the TDD is controlled through SPI or GPIO pins and the override value. 


    Regards,

    David Chaparro