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AFE8030EVM: SPI is not working on AFE8030

Shiva Pinagani
Prodigy 60 points
Part Number: AFE8030EVM
Other Parts Discussed in Thread: AFE8030, LMK04828

Hi Team,

We have 6 EVMs and all of them have been modified for SPI access via FMC. Following changes have been made:

  1. The resistors connecting FMC pins to SPI signals have been mounted and the resistors connecting FTDI signals to SPI signals have been removed.
  2. Resistors connecting FMC pins to LMK SPI signals have been mounted and the resistors connecting FTDI signals to SPI signals have been removed.
  3. Resistors have been mounted to get JESD core clock from LMK to FMC.

 

Initially, on 4 of the EVMs, I couldn’t access the AFE chip via SPI. Then I connected the USB cable to the EVM and the FTDI part got powered up and things started working! I could do SPI access and read chip ID for example. So, now I have connected the 5V SOURCE to the 5V IN of the FTDI chip.  I have disconnected the USB VBUS pin from feeding the FTDI chip. Is this a proper thing to do? The SPI and LMK_SPI signals are being driven from the FMC connector. Two of the EVMs work without this modification. and 4 EVMs which I am not able to access AFE chip but i am able to  program the LMK  can you please help with this .

 

  • 0
    TI__Intellectual 2645 points

    Shiva,

    I don't believe you should need to connect the USB cable for the AFE SPI to work over FMC. To help me debug further, can you please list out all of the Resistor value changes (and any other hardware changes you've made)? 

    Have you set up the AFE to use 3-wire SPI or 4-wire SPI? If you're not sure, can you please share your configuration Excel/JSON/HEX and I can review?

    Thanks,

    Ben

  • 0 in reply to Benjamin Uhing
    Prodigy 60 points

    The following modifications have been done for SPI connection between FMC and AFE and FMC and LMK

     

    1. SPIA connection between FMC and AFE8030 chip
    2. Populate R424, R420, R408, R405 with 0 ohm resistors (footprint is 0201)
    3. Populate R76, R75, R74, R73 with 0 ohm resistors (footprint is 0402)
    4. DNI (Remove) R232, R233, R234, R238 resistors to disconnect from USB FTDI chip (footprint is 0402 , 49.9 ohm)

     

    1. SPI connection between FMC and LMK04828 chip
    2. R99 is already DNI (Removed) (footprint is 0402 , 0 ohm)
    3. DNI (Remove) R205, R211, R212 resistors to disconnect from USB FTDI chip (footprint is 0402 , 0ohm)
    4. Populate R457, R458, R459, R460 with 0 ohm resistors (footprint is 0201)

     

    We have also made modifications for core JESD clock

    1. Core Clock for JESD
    2. Populate R317,R322 with 0 ohm resistors (footprint is 0402)
    3. Populate R316,R324 with 240 ohm resistors (footprint is 0402)

     

     

    I noticed the following things.

    1. I switch on the EVM power supply and connect USB cable. Then I start the FPGA board. The SPI connection works.
    2. I remove the USB cable. SPI still works.
    3. I keep the USB cable and switch off the EVM 5V power supply and switch it back on. SPI connection is lost
    4. After I switch off the EVM 5V power supply and switch it back on, if I disconnect and reconnect the USB cable, the SPI connection starts working again.

     

    It looks like powering on the FTDI chip does something and puts the AFE chip in the right state!

    The below is our config file  we are using AFE to 4-wire SPI only .
    exp4_a_d.xlsx

  • 0 in reply to Shiva Pinagani
    TI__Guru 69344 points

    Hi Shiva,

    Please advise ground connections between the FPGA board and the AFE80xx EVM. We have experienced SPI failures before due to poor ground connections between the FPGA and the AFE80xx EVM before. Please check if somehow the USB is helping connecting the ground between the two boards.