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TIDA-00828: Inductive sensing based incremental encoder

1226631
Prodigy 120 points
Part Number: TIDA-00828
Other Parts Discussed in Thread: LAUNCHXL-F28069M, , TIDA-00508, LDC1314, LDC0851

 Can  inductive sensing based incremental encoder such as reference design TIDA-00828 used instead of incremental optical absolute encoders with LAUNCHXL-F28069M InstaSPIN-MOTION.

  • 0
    TI__Genius 13335 points
    Hello,
    Can you help clarify the request? The TIDA-00828 is a complete system including the knob, sensors, micro-controller, and 7-segment display to indicate the increment/decrement value. If the question relates to using an inductive-based solution to do an absolute position application then I would recommend to take a look at the TIDA-00508 solution (www.ti.com/.../TIDA-00508) which uses a 4-channel device, LDC1314, to achieve 1-degree accurate position over 360 degree rotation. This is the simplest method to achieve absolute position using inductive sensing.
    Note the TIDA-00828 uses the LDC0851 which is a 1-bit output device. So if you were to adapt the LDC0851 to achieve absolute position then each LDC0851 you add increases the resolution by 1 bit, similar to an optical encoder solution. You can calculate the resolution as 360 degrees / (2^N) where N is the number of LDC0851 devices. For example, if you want to achieve 1 degree absolute position it would take up to nine LDC0851 devices (or optical switches), where it only requires a single LDC1314 in the TIDA-00508 design.
    Regards,
    Luke
  • 0 in reply to Luke LaPointe
    Prodigy 120 points
    My apologies not clarifying my question, but your answer was very precise and that what I was looking for answer. Somehow I missed the TIDA-00508 in TI development kit. My question: to get the angle in incremental of 1 degree over 1 revolution (360, bin 101101000) 10 Bit , LDC1314 has 12 bit sampling rate enough to get 1 degree accuracy over 200 rmp. Do you agree, if rmp increased over 200, to be able to sample the data, the LDC1314 detects the inductance change by measuring frequency of the LC tank, therefore if the frequency is increased and the LC value is configured to achieve resonance, I may be able to go over 200rpm.
  • 0 in reply to 1226631
    TI__Genius 13335 points
    Hello,
    There will be an accuracy vs speed tradeoff. We say that there is 1 degree accuracy up to 200 rpm. If you rotate faster than this the instantaneous accuracy may drop below 1 degree, but once you return below 200 rpm you will get the accuracy back. Depending on your speed requirements, you may consider using a gear ratio so that the LDC target spins slower than the gears.
    -Luke