[55] I2S: RXPTRUPD and TXPTRUPD events asserted after STOP

This anomaly applies to IC Rev. Rev 1, build codes QFAA-B00, QFAB-B00, CIAA-B00.

It was inherited from the previous IC revision Engineering C.

Symptoms

The RXPTRUPD event is generated when the STOP task is triggered, even though reception (RX) is disabled. Similarly, the TXPTRUPD event is generated when the STOP task is triggered, even though transmission (TX) is disabled.

Conditions

A previous transfer has been performed with RX/TX enabled, respectively.

Consequences

The indication that RXTXD.MAXCNT words were received/transmitted is false.

Workaround

Ignore the RXPTRUPD and TXPTRUPD events after triggering the STOP task. Clear these events before starting the next transfer.