SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
If the index event occurs during the forward movement, then position counter is reset to 0 on the next EQEP clock. If the index event occurs during the reverse movement, then the position counter is reset to the value in the EQEP_QPOSMAX register on the next EQEP clock.
First index marker is defined as the quadrature edge following the first index edge. The EQEP peripheral records the occurrence of the first index marker (EQEP_QEP_STS_CT[1] FIMF) and direction on the first index event marker (EQEP_QEP_STS_CT[6] FIDF) in EQEP_QEP_STS_CT registers, it also remembers the quadrature edge on the first index marker so that same relative quadrature transition is used for index event reset operation.
For example, if the first reset operation occurs on the falling edge of EQEPB during the forward direction, then all the subsequent reset must be aligned with the falling edge of EQEPB for the forward rotation and on the rising edge of EQEPB for the reverse rotation as shown in Figure 12-373.
The position-counter value is latched to the EQEP_QPOSILAT register and direction information is recorded in the EQEP_QEP_STS_CT[4] QDLF bit on every index event marker. The position-counter error flag (EQEP_QEP_STS_CT[0] PCEF) and error interrupt flag (EQEP_QINT_EN_FLG[17] PCEI_FLG) are set if the latched value is not equal to 0 or QPOSMAX. The position-counter error flag (EQEP_QEP_STS_CT[0] PCEF) is updated on every index event marker and an interrupt flag (EQEP_QINT_EN_FLG[17] PCEI_FLG) will be set on error that can be cleared only through software.
The index event latch configuration EQEP_QDEC_QEP_CTL[21-20] IEL bits are ignored in this mode and position counter error flag/interrupt flag are generated only in index event reset mode.