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Original question:

LMK04828: LMK04828

LMK04828: SPI 3 wire non responsive

Corey Hirn
Prodigy 100 points
Part Number: LMK04828

Hello, I had previously ask if the below circuit was correct for testing just the SPI communication of the chip ( https://e2e.ti.com/support/clock-and-timing/f/48/t/760667 

What I have tried.

I found the following https://e2e.ti.com/support/clock-and-timing/f/48/p/649396/2386845?tisearch=e2e-sitesearch&keymatch=afe58jd18evm#2386845

power consumption on a powerdown instruction. I have verified that RESET(pin 5) is tied low

I found the following https://e2e.ti.com/support/clock-and-timing/f/48/t/505076?LMK04828-Not-listening-or-responding-to-SPI 

Reset (pin 5) 0v

LDObyp1 (pin 11) ~2.5v

LDObyp2(pin 12) ~1.5v

OSCin (43) ~1.6v

CLKin0 (37) ~1.6v

status_LD1 (31) 0

status_LD2 (48) 0

CLKin_sel0 (58) 0

CLKin_sel1 (59) 0

the circuit above is drawing .355A at 3.3v , I have switched out IC's and have observed the same results. 

I tried a loop to change the status_LD1 by writing  register 0x149 a value of 0x03 and then changing it to a value of 0x04. below is an example of the write. The values taken are measured at the chip 

  • 0
    TI__Mastermind 27851 points
    Corey,

    OK, so it looks like you are sending a serial command and the lock detect is toggling. In general, when testing serial communicaitons, it is best to choose a rudimentary serial command that does not have a lot of other dependencies. Lock detect seems to be working for you, but maybe I'm missing something. Also you can toggle the POWERDOWN bit (R2[0]) and test the reaction to that serial command.

    Regards,
    Dean
  • 0 in reply to Dean Banerjee
    Prodigy 100 points

    Thats interesting, every other line of text next to the images are missing. lets see if I can clear this up. 

    From the forum I Found 2 ways to verify SPI communication. The first was to send a command to power down. 

    "Also you can toggle the POWERDOWN bit (R2[0]) and test the reaction to that serial command." I have tried this. I do not see a reduction in power consumption indicating the device is shutting down. A side note I do not see a reduction in power when I raise the RESET/GPO pin high either. 

    The second method I found was to toggle the output type between Output and Invert Output of the STATUS_LD1 pin. This was done by  writing  register 0x149 a value of 0x03 and then changing it to a value of 0x04. I did not observer any change on the Status_LD1 pin. 

    Hope that clarifies what I have tried. 

  • 0 in reply to Corey Hirn
    Prodigy 100 points
    I solved the Issue. I had a noisy CS line added a cap and fixed the issue.