SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
The eQEP inputs include two pins for quadrature-clock mode or direction-count mode, an index (or 0 marker), and a strobe input. The eQEP module requires that the QEPA, QEPB, and QEPI inputs are synchronized to SYSCLK prior to entering the module. The application code can enable the synchronous GPIO input feature on any eQEP-enabled GPIO pins.
These two pins can be used in quadrature-clock mode or direction-count mode.
The eQEP encoders provide two square wave signals (A and B) 90 electrical degrees out of phase. This phase relationship is used to determine the direction of rotation of the input shaft and number of eQEP pulses from the index position to derive the relative position information. For forward or clockwise rotation, QEPA signal leads QEPB signal and conversely. The quadrature decoder uses these two inputs to generate quadrature-clock and direction signals.
In direction-count mode, direction and clock signals are provided directly from the external source. Some position encoders have this type of output instead of quadrature output. The QEPA pin provides the clock input and the QEPB pin provides the direction input.
The eQEP encoder uses an index signal to assign an absolute start position from which position information is incrementally encoded using quadrature pulses. This pin is connected to the index output of the eQEP encoder to optionally reset the position counter for each revolution. This signal can be used to initialize or latch the position counter on the occurrence of a desired event on the index pin.
This general-purpose strobe signal can initialize or latch the position counter on the occurrence of a desired event on the strobe pin. This signal is typically connected to a sensor or limit switch to notify that the motor has reached a defined position.
Input signals to the eQEP (QEPA, QEPB, QEPI and QEPS) can come from multiple sources; that is, device pin, CMPSSx, or PWMXBARx. One typical use case is if SinCos transducers are used in the motor control system to estimate the position of motor shaft and Index signal is coming from traditional rotary encoder, source of the eQEP signals (QEPA, QEPB and QEPI) can be configured as output of CMPSSx which decodes the Sin, Cos and Index signals. Figure 7-291 illustrates the use case.
Selection of the source of Input signals (QEPA, QEPB, and QEPI) is user-configurable through the QEPSRCSEL register as shown in eQEP Input Source Select Table.
QEPSRCSEL. QEPASEL |
Source for QEPA | QEPSRCSEL. QEPBSEL |
Source for QEPB |
---|---|---|---|
0 | Tie-low | 0 | Tie-low |
1 | EQEP_A_PAD | 1 | EQEP_B_PAD |
2 | PWMXBAR.OUT0 | 2 | PWMXBAR.OUT0 |
3 | PWMXBAR.OUT1 | 3 | PWMXBAR.OUT1 |
4 | PWMXBAR.OUT2 | 4 | PWMXBAR.OUT2 |
5 | PWMXBAR.OUT3 | 5 | PWMXBAR.OUT3 |
6 | PWMXBAR.OUT4 | 6 | PWMXBAR.OUT4 |
7 | PWMXBAR.OUT5 | 7 | PWMXBAR.OUT5 |
8 | PWMXBAR.OUT6 | 8 | PWMXBAR.OUT6 |
9 | PWMXBAR.OUT7 | 9 | PWMXBAR.OUT7 |
10 | PWMXBAR.OUT8 | 10 | PWMXBAR.OUT8 |
11 | PWMXBAR.OUT9 | 11 | PWMXBAR.OUT9 |
12 | PWMXBAR.OUT10 | 12 | PWMXBAR.OUT10 |
13 | PWMXBAR.OUT11 | 13 | PWMXBAR.OUT11 |
14 | PWMXBAR.OUT12 | 14 | PWMXBAR.OUT12 |
15 | PWMXBAR.OUT13 | 15 | PWMXBAR.OUT13 |
16 | PWMXBAR.OUT14 | 16 | PWMXBAR.OUT14 |
17 | PWMXBAR.OUT15 | 17 | PWMXBAR.OUT15 |
18 | PWMXBAR.OUT16 | 18 | PWMXBAR.OUT16 |
19 | PWMXBAR.OUT7 | 19 | PWMXBAR.OUT7 |
20 | PWMXBAR.OUT18 | 20 | PWMXBAR.OUT18 |
21 | PWMXBAR.OUT19 | 21 | PWMXBAR.OUT19 |
22 | PWMXBAR.OUT20 | 22 | PWMXBAR.OUT20 |
23 | PWMXBAR.OUT21 | 23 | PWMXBAR.OUT21 |
24 | PWMXBAR.OUT22 | 24 | PWMXBAR.OUT22 |
25 | PWMXBAR.OUT23 | 25 | PWMXBAR.OUT23 |
26 | PWMXBAR.OUT24 | 26 | PWMXBAR.OUT24 |
27 | PWMXBAR.OUT25 | 27 | PWMXBAR.OUT25 |
28 | PWMXBAR.OUT26 | 28 | PWMXBAR.OUT26 |
29 | PWMXBAR.OUT27 | 29 | PWMXBAR.OUT27 |
30 | PWMXBAR.OUT28 | 30 | PWMXBAR.OUT28 |
31 | PWMXBAR.OUT29 | 31 | PWMXBAR.OUT29 |