• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 31 subscribers
  • Views 820 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LDC1101 Sample Rate

Jan Rosenfelder
Prodigy 90 points
Other Parts Discussed in Thread: LDC1101EVM, LDC1101

Hello,

i have the LDC1101EVM and try to have a good resolution with a high Sample Rate.

The Formula for the conversion time in LHR-Mode is: tconv = (55 + RCOUNT x 16) / fCLKIN

I found the valid range in the description SNOSD01C is : 2 ≤ RCOUNT[15:0] ≤ 65535 

So i can calculate the maximum sample rate for RCOUNT = 2  -> 134 ksps with 16MHz fCLKIN and 100 ksps with 12 MHz

minimum sample rate is RCOUNT = 65535  -> 15 sps with 16 MHz and 11 with 12 MHz

So the maximum sample rate with 180ksps is only in RP+L-Mode possible?

But when i open the LDC1101 EVM GUI v.1.0.0.6 and go the LHR configuration i can choose the RCOUNT from 64-1.048.560

so i have a maximum sample rate by RCOUNT = 64 ->  11ksps

and minimum sample rate RCOUNT = 1.048.560 ->  0,7 sps

I have the highest resolution with 1.048.560  ... but it is very very slow ... is that true?

But how can i find out my current sample rate in the gui?

Best regards Jan

  • 0
    TI__Genius 13650 points
    Hello Jan,
    there is a trade-off between sample rate and resolution. The equations for calculating the sample rate are described in the LDC1101 datasheet.
    L-only mode has a higher maximum sample rate the RP+L mode.

    Note that the LDC1101 is capable of sampling at up to 183ksps, but the GUI architecture and Firmware do not support reading back at these rates. Therefore, you will only be able to capture samples at approximately 1ksps max if you are using our GUI/FW.
  • 0 in reply to Ben Kasemsadeh
    Prodigy 90 points
    Hello Ben,
    thanks for the information.
    I tried the GUI with the highest resolution and get every 87ms a new value (same value like LDC1101 description)
    Then I tried the lowest resolution an set the register 0x30 to 0x04 and 0x31 to 0x00 -> that should be the lowest resolution with 183,9ksps@16Mhz ... but I got also every 87ms a new value.
    I tried to change the usb polling rate to 1000 hz with a tool called "hidusbf" ... but i get the same result.
    The next step was your Labview-Programm for LDC1000 .... i change the register to the LDC1101 Register and plot the LHR-Output-Code .... and got the same result, only 11 sps with the LDC1101EVM.
    What could be there wrong?
    Best regards,
    Jan