38.7.22 Device Endpoint Interrupt Mask Register (Isochronous Endpoints)

This bit is set when USBHS_DEVEPTIERx.RSTDTS = 1. This clears the data toggle sequence, i.e., sets to Data0 the data toggle sequence of the next sent (IN endpoints) or received (OUT endpoints) packet.

This bit is cleared instantaneously.

The user does not have to wait for this bit to be cleared.

This bit is set when USBHS_DEVEPTIERx.EPDISHDMAS = 1. This pauses the on-going DMA channel x transfer on any Endpoint x interrupt (PEP_x), whatever the state of the Endpoint x Interrupt Enable bit (PEP_x).

The user then has to acknowledge or to disable the interrupt source (e.g. USBHS_DEVEPTISRx.RXOUTI) or to clear the EPDISHDMA bit (by writing a one to the USBHS_DEVEPTIDRx.EPDISHDMAC bit) in order to complete the DMA transfer.

In Ping-pong mode, if the interrupt is associated to a new system-bank packet (e.g. Bank1) and the current DMA transfer is running on the previous packet (Bank0), then the previous-packet DMA transfer completes normally, but the new-packet DMA transfer does not start (not requested).

If the interrupt is not associated to a new system-bank packet (USBHS_DEVEPTISRx.NAKINI, NAKOUTI, etc.), then the request cancellation may occur at any time and may immediately pause the current DMA transfer.

This may be used for example to identify erroneous packets, to prevent them from being transferred into a buffer, to complete a DMA transfer by software after reception of a short packet, etc.

For control endpoints:

The FIFOCON and RWALL bits are irrelevant. Therefore, the software never uses them on these endpoints. When read, their value is always 0.

For IN endpoints:

0: Cleared (by writing a one to the USBHS_DEVEPTIDRx.FIFOCONC bit) to send the FIFO data and to switch to the next bank.

1: Set when the current bank is free, at the same time as USBHS_DEVEPTISRx.TXINI.

For OUT endpoints:

0: Cleared (by writing a one to the USBHS_DEVEPTIDRx.FIFOCONC bit) to free the current bank and to switch to the next bank.

1: Set when the current bank is full, at the same time as USBHS_DEVEPTISRx.RXOUTI.

The bank is really killed: USBHS_DEVEPTISRx.NBUSYBK is decremented.

The bank is not cleared but sent (IN transfer): USBHS_DEVEPTISRx.NBUSYBK is decremented.

The bank is not cleared because it was empty.

The user should wait for this bit to be cleared before trying to kill another packet.

This kill request is refused if at the same time an IN token is coming and the last bank is the current one being sent on the USB line. If at least two banks are ready to be sent, there is no problem to kill a packet even if an IN token is coming. Indeed, in this case, the current bank is sent (IN transfer) while the last bank is killed.

If this bit is set for non-control IN endpoints, a short packet transmission is guaranteed upon ending a DMA transfer, thus signaling an end of isochronous frame or a bulk or interrupt end of transfer, provided that the End of DMA Buffer Output Enable (END_B_EN) bit and the Automatic Switch (AUTOSW) bit = 1.