SPRAC77E January 2022 – February 2022 TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S
This decoder implementation is similar to the C2000 eQEP peripheral operating in quadrature-count mode. Table 5-1 provides a high-level comparison of the features supported. In some cases, potential modifications have been provided. Refer to the device-specific Technical Reference Manual for a detailed description of the eQEP peripheral.
eQEP Feature | QepOnClb Support | |
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Quadrature-clock mode (QEP-A/B signals) | Detect direction, count, and invalid state transitions. | Implemented. The current state of the QEP-A/B signals is compared to the previous state. The phase relationship determines the direction of movement. If both signals change at the same time, then an invalid state transition is detected. |
An invalid state transition sets a flag or optionally generates an interrupt. | Implemented. The CLB will issue an interrupt on an invalid state transition. If instead a flag is desired, the CLB interrupt tag can be used and the interrupt left disabled. |
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Configure 4x count: both the rising and falling edge of both QEPA/B | Implemented as: Both the rising and falling edges of QEPA/B generate a count. This behavior can be changed by modifiying the QCLK state machine. |
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Reverse count (reverse QEP-A/B inputs) | Not implemented. To implement, modify the CLB configuration to swap the QCLK state machine inputs. |
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Direction-count mode (XCLK and DIR signals) | QEP-A becomes XCLK and QEP-B becomes DIR. | Not implemented. To implement, modify the CLB configuration and (1) disconnect DIR (QEP-B) from the direction decode LUT and (2) connect DIR directly to the direction control, mode 1, of the counter. |
QEP-I (index or zero signal) | Latch the position counter which can then be read using a driverlib function. This can be configured to be rising-edge, falling-edge or event marker/software index marker based. | Implemented as: Latch the position counter on the QEP-I rising-edge. The position counter value can be read from the HLC FIFO using a provided library function. On some devices the HLC can be configured to respond to a falling-edge instead of rising-edge. |
Initialize the position counter. | Not implemented. To implement, modify the HLC program to initalize the counter with a value pulled from the FIFO. |
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Reset the position counter. | Not implemented. To implement, route the QEP-I signal to the QEP reset generation LUT and it into the LUT's equation. |
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QEP-S (strobe signal) | Latch the position counter o reset the position counter. | Not implemented. Can be implemented by following the QEP-I example. |
Position counter operating modes | Reset on index, maximum position, first index or unit time-out event. | Implemented as: Reset on a maximum position value. This value is configured through a provided library function pto_qeponclb_configMaxCounterPos(). Refer to Section 7.6. |
Position compare unit | Not implemented. | |
Edge capture unit | Not implemented. | |
Watchdog | Not implemented. | |
Unit timer base (QUTMR) | Not implemented. |