Hi,
Using the eQEP2 peripheral to determine absolute position with POSCNT:
QEPA and QEPB are connected to Hall effect sensor delivering 2 clean square signals with 60° phase shift and period of 700 microseconds minimum. Purpose is to get absolute position cumulated count after initialization to 0x80000000. Mode used is QUADRATURE_COUNT without index event nor strobe. Vclk is 25 MHz.
Position is read every 10 ms cycle. I noticed discrepancies compared to a reference value (see curve below - purple = ref, blue dashed = eQEP value, vertical scale is a position in millimeters, time scale is in seconds):
- reduced increments between 2 cycles (-1, 0 , +1, rarely-2 or +2 ) whereas I expected up to -6 to + 6 increment values between 2 successive reads considering real rotating speed.
- multiple inversions of incremental direction when rotating speed is higher and whereas no direction changes in real
Has someone any idea of check points in my configuration regarding these symptoms?
Regards
Xav
