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Tool/software:
Hello,
I would like to know the exact information regarding the title. Please give me an answer.
Background:
I am developing a device that uses this MCU to make the motor reciprocate. Currently, when the motor passes through the origin (when it crosses the Z-Pulse), I am encountering a phenomenon where the eQEP value deviates from what I expected.
The settings for each device are as follows：
Encoder IC: ABZ pulse output method
* AB Direction: A leading B.
* Z Gating: Z at AB=10 (Z-Pulse is HI during the period when A-Pulse is HI and B-Pulse is LO.)
* Z Polarity: Z-Pulse is active hi.
MCU eQEP:
* Position Counter source: Quadrature-clock mode
* Resolution: 2x Resolution (Count rising and falling edge)
* Index pulse gating: Gate the index pin with strobe.
* Position counter mode: Reset position on index pulse.
* Maximum position: 131072 (20000h)
* Position Counter(QPOSCNT): 0
* QEP Capture Latch Mode(QCLM): On position counter read.
* Strobe Event Latch(SEL) : On rising edge with clockwise, on falling when counter clockwise.
* Index Event latch(IEL): On rising edge of index.
* Position Strobe Events(SEI): On rising edge with clockwise, on falling when counter clockwise.
* Position Index Event(IEI): On rising edge of index.
* Set software initialization position counter: checked.
* Position counter initialization value: 0
* Enable Position counter: checked.
The following is a graphical representation of the operation I envisioned.
When running clockwise, I would assume that the index event occurs on QCLK after the rising edge of Z-Pulse.
Question)
1) Is the timing of the index event correct for a clockwise operation?
2) What are the conditions for an index event to occur during counterclockwise operation?
3) Is there anything wrong with my setting of Z-Pulse gating with AB=10 (Z-Pulse is HI during the period when A-Pulse is HI and B-Pulse is LO.) in the ”Reset position on index pulse”？
Hi Mr.Ryan,
Thank you for your quick response.
I did not use the eQEP sample code included in the SDK. I created a syscfg file and configured eQEP on that screen.
I use tilt sensor measurements to check the continuity of eQEP values. The principle is described below.
* Attach the mirror to the motor's rotary shaft.
* The tilt sensor is a measuring instrument that measures tilt, so if it is installed perpendicular to the mirror, the tilt will remain zero.
* Turning the motor's rotary axis to the left or right increases the tilt and creates a continuous trajectory like the red line of the expected motion.
However, in reality, when there is a Z-Pulse, the tilt value shifts at the origin (Z-Pulse detection) position, as shown in the rightmost graph.
If the Z-Pulse is shifted so that it is not detected during rotation, the tilt value will transition continuously.
I think the value is shifted by the reset action at the time of Z-Pulse detection.
Best regard. Teruhiko Ozuchi.
Hi Mr.Ryan,
Attached is a capture of the eQEP settings from the syscfg screen.
#1
#2
#3
As mentioned earlier, the current Z-Pulse setting is “Z Gating: Z at AB=10 (Z-Pulse is HI during the period when A-Pulse is HI and B-Pulse is LO”.
(Settings in the leftmost figure below)
The Z-Pulse Gating can also be changed by setting the encoder IC as follows.
Best regard. Teruhiko Ozuchi
