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ADS54J64EVM: ADS54J66EVM SPI communication with LMK04828

Daniel Stindl
Intellectual 325 points
Part Number: ADS54J64EVM
Other Parts Discussed in Thread: LMK04828

Hello

I have a problem with configuration ADS54J64EVM (ADC+LMK) through FMC (JP3 in 1-2 position).

I'm able to communicate with ADc but not with LMK. I believe there is a problem with controlling FMC_DIR_CONTROL signal. My colleaque is trying to understand and simulate provided CPLD code. In meantime I would to try 4-wire SPI configuration of LMK04828.

From my understanding of what to do:

1.) Add 0 ohm resistor on R113

2.) Master SPI controller should be in 4-wire configuration for both ADC and LMK

3.) Write to LMK04828:

write(0x0000,0x80); //reset
write(0x0000,0x10); //disable 3-wire
write(0x014A,0x33); //enable RESET pin for SPI readback, push-pull driver
4.) FMC_DIR_CONTROL is no care?
Thanks and regards
Dan


  • 0
    TI__Guru* 91947 points

    Dan,

    Set bit 6 to a "1" for address 0x149. I did not do the CPLD code but I think FMC_DIR_CONTROL is not used. 

    Regards,

    Jim

  • 0 in reply to jim s
    Intellectual 325 points

    Hi

    I soldered R113 and tried this pseudo-code before reading registers:

        spi_write(hmc, 0x0, 0x80); //reset
        spi_write(hmc, 0x0, 0x10); //3 wire
        spi_write(hmc, 0x0145, 0x7F); //see datasheet
        spi_write(hmc, 0x14A, 0x33); //3 wire
        spi_write(hmc, 0x149, 0x42); //open drain SDIO
        spi_write(hmc, 0x0171, 0xAA); //see datasheet
        spi_write(hmc, 0x0172, 0x2); //see datasheet
        spi_write(hmc, 0x017C, 0x15); //see datasheet
        spi_write(hmc, 0x017D, 0x33); //see datasheet

    Without a success. The response is 0xFF for all registers.

    We are reading the CPLD code and it seems the LMK_SDO is internally wired to output signal FMC_LMK_SDIO what is unconnected on the kit. So the 3-wire is the only way.

    Regards,

    Dan

  • 0 in reply to Daniel Stindl
    TI__Guru* 91947 points

    Dan,

    The CPLD code was written a long time ago by another engineer and I have a feeling it was never tested for 4 wires SPI mode using the FMC case. If you need to use 4-wire SPI mode, there is a good chance this firmware will need to be modified.

    Regards,

    Jim

  • 0 in reply to jim s
    TI__Guru* 91947 points

    Dan,

    One suggestion is to make a new firmware build that only allows the use of the FMC input/outputs. Just unassigned the USB signals and pass the FMC signals straight though. This should be relatively simple.

    Regards,

    Jim

  • 0 in reply to jim s
    Intellectual 325 points

    Hi,

    We will try to get it work with 3-wire. My co-worker just simulate the CPLD code with our spi ip core.

    Otherwise we will bypass CPLD with simple firmware as you said.

    Regards,

    Dan