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problem with atmega and LDC1000 SPI communication

Kashyap Patalia
Prodigy 55 points
Other Parts Discussed in Thread: LDC1000EVM

hi there,

i have got one problem in my project. when initiate communication between LDC1000 breakout and my atmega16 board all works fine until i write the power register.

all registers are written and can be read perfectly except power config register. when i set all registers and then when i write 0x01 into power register all registers are reset to their default values and nothing happens. and power register shows 0x00 instead of 0x01. please help me.

thank you in advance.

please reply soon.

  • 0
    TI__Expert 6550 points
    Hello Kashyap,

    You should check that you are following the power sequence. Please, refer to the electrical characteristics table on page 5 of the datasheet.

    Best Regards,
    Natallia Holubeva
  • 0 in reply to Natallia Holubeva1
    Prodigy 55 points

    Thank you Natallia for the reply.

    I have checked my power supply and connections. all are working fine and on 5V supply. and ofcourse i can read andwrite any register except Power Config (0x0B) register.

    What I am doing is firstly I set all config registers to desired values and double-check them all for proper communication. They all work well.

    Now when I lastly write the power register 0x0b to the value 0x01 and again read all the config registers they all shows their default values and power registers shows 0x00 value. Also the proximity data shows 0x00.

    I have tested two LDC1000 ICs. They both behave similarly and the problem is same. Please suggest me some solution.

    Thank you again.

  • 0 in reply to Kashyap Patalia
    TI__Expert 6550 points
    Hello,

    Thank you for explanation. I would need more system information to assist.

    1. What coil are you using? Is it LDC1000EVM coil? What is the target?
    2. Are you using same register settings as the EVM? If not, what are your register settings?
    3. Please check the voltages on each pin, especially on VIO.

    Best Regards,
    Natallia Holubeva
  • 0 in reply to Natallia Holubeva1
    Prodigy 55 points
    Thank you Natallia for the reply.
    about my system:
    1. I am using one voice coil. and target is one cast iron rod.
    2. Yes, most probably all register values are same.
    3. I am getting 5 volts on both pins i.e., VDD and VIO, i have shorted them together and giving them 5 volts supply.

    Thank You again.
  • 0 in reply to Natallia Holubeva1
    Prodigy 55 points
    hi again,
    do you have any example code for avr uC i.e., atmega8/16/32. if you can mail me on khpatalia.ece@gmail.com
    that would help me a lot.
    thank you in advance.
  • 0 in reply to Kashyap Patalia
    TI__Genius 14270 points
    Hello Kashyad,
    Unfortunately, we do not have any atmega code for interfaceing to the LDC.
    I apologize for asking so many questions, but the behavior you are describing is unexpected. The fact that 2 LDCs exhibit this response is very helpful information. Are you using the center break-out section of the EVM? Or are you using your own PCB? The only the only thing that I can think of that could cause the issue you are seeing is a problem with the supply bypassing. Do you have bypass caps to ground for VDD, VIO, and CLDO? If so, what are the values?
    Regards,ChrisO
  • 0 in reply to Chris Oberhauser66
    Prodigy 55 points

    hello Chris,

    Thanks for the reply. I don't see any problem you asking these questions. and thanks to TI for concerning my issue. and yes I am facing these problems in both my LDC1000 ICs. And i would like to inform you that i have designed my own breakout board. On VDD pin i have two caps in parallel having values 0.1uF and 1uF. same is for VIO pin and for CLDO pin i have used 56nF cap.

    Thank you in advance.

    regards,

    Kashyap Patalia

  • 0 in reply to Kashyap Patalia
    TI__Genius 14270 points
    Hello Kashyap,

    The bypassing seems fine. Did you set the MIN_FREQ register (address 0x03) properly? Try putting it to a very low value (use a register setting corresponding to 5kHz), and then see if the sensor starts oscillating (check the INA or INB pin to ground with a scope and measure the frequency). Do you have an LDC1000EVM center section which you can use instead of your board?

    Regards,

    Chris O