Hi team,
My customer use TMS320F28375D in their project, and they meet below issues about the eQEP, could you please help on give some suggestions? Thank you!
1. Competitive risk
Set QEPCTL.bit.PCRM=1，QPOSMAX=0xFFFFFFFF，QEPCTL.bit.IEL=1，
When the index rising edge and the edge of A or B arrive simultaneously, the QPOSILAT latch value is sometimes 1 different when both measured in the same operating direction;
As shown in the figure, when the index rises to the positive direction, The value that should be latched is 0, but sometimes it is locked to 1;
When running in the opposite direction, when index rises, the value that should be latched is 2, but sometimes it will be locked to 1;
2. FIMF: The question of how first index marker flag is defined
As shown in the figure above, assuming the encoder is in position A when powered up, the encoder moves in the order A->B->A->B->C , When measured, the eQEP module will record the reverse motion of QA at D as a rising edge as FIMF, which is not one of the four edges of the QA QB during the period when index is high; if QEPCTL.bit.PCRM=1 is set, QPOSMAX=0xFFFFFFFF,QEPCTL.bit.IEL=3, and the next edge of the latch event will not obviously be this edge at D.
3. Index uses only the quadrature edge after its rising edge as an index event, but there are actually encoders where the index pin outputs a high level when the index signal does not arrive, and the index pin outputs a low level when the index signal arrives. This logic is the opposite of what qep needs; although it can be solved by setting index polarity, it lacks versatility. Is not sure if there is a better solution?
For the three questions, could you please help give some questions? Thank you!
