Revisions Affected

B, C

Details

If any of the eQEP input pins are configured for GPIO asynchronous input mode via the GPxQSELn registers, the eQEP module may not operate properly because the eQEP peripheral assumes the presence of external synchronization to SYSCLKOUT on inputs to the module. For example, QPOSCNT may not reset or latch properly, and pulses on the input pins may be missed.

For proper operation of the eQEP module, input GPIO pins should be configured via the GPxQSELn registers for synchronous input mode (with or without qualification), which is the default state of the GPxQSEL registers at reset. All existing eQEP peripheral examples supplied by TI also configure the GPIO inputs for synchronous input mode.

The asynchronous mode should not be used for eQEP module input pins.

Workarounds

Configure GPIO inputs configured as eQEP pins for non-asynchronous mode (any GPxQSELn register option except “11b = Asynchronous”).