38.6.2.16 HB IsoIn Error

This error only exists for high-bandwidth isochronous IN endpoints.

At the end of the microframe, if at least one packet has been sent to the host and fewer banks than expected have been validated (by clearing the USBHS_DEVEPTIMRx.USBHS_DEVEPTIMRx.FIFOCON) for this microframe, it sets the USBHS_DEVEPTISRx.HBISOINERRORI bit, which triggers a PEP_x interrupt if the High Bandwidth Isochronous IN Error Interrupt Enable (HBISOINERRORE) bit is one.

For example, if the Number of Transactions per MicroFrame for Isochronous Endpoint (NBTRANS) field in USBHS_DEVEPTCFGx is three (three transactions per microframe), only two banks are filled by the CPU (three expected) for the current microframe. Then, the HBISOINERRI interrupt is generated at the end of the microframe. Note that an UNDERFI interrupt is also generated (with an automatic zero-length-packet), except in the case of a missing IN token.