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DocID018909 Rev 11 1303/1731

RM0090 USB on-the-go full-speed (OTG_FS)

1368

Bit 17 NAKSTS: NAK status

It indicates the following:

0: The core is transmitting non-NAK handshakes based on the FIFO status.

1: The core is transmitting NAK handshakes on this endpoint.

When either the application or the core sets this bit:

For non-isochronous IN endpoints: The core stops transmitting any data on an IN endpoint,

even if there are data available in the TxFIFO.

For isochronous IN endpoints: The core sends out a zero-length data packet, even if there

are data available in the TxFIFO.

Irrespective of this bit’s setting, the core always responds to SETUP data packets with an

ACK handshake.

Bit 16 EONUM: Even/odd frame

Applies to isochronous IN endpoints only.

Indicates the frame number in which the core transmits/receives isochronous data for this

endpoint. The application must program the even/odd frame number in which it intends to

transmit/receive isochronous data for this endpoint using the SEVNFRM and SODDFRM

fields in this register.

0: Even frame

1: Odd frame

DPID: Endpoint data PID

Applies to interrupt/bulk IN endpoints only.

Contains the PID of the packet to be received or transmitted on this endpoint. The

application must program the PID of the first packet to be received or transmitted on this

endpoint, after the endpoint is activated. The application uses the SD0PID register field to

program either DATA0 or DATA1 PID.

0: DATA0

1: DATA1

Bit 15 USBAEP: USB active endpoint

Indicates whether this endpoint is active in the current configuration and interface. The core

clears this bit for all endpoints (other than EP 0) after detecting a USB reset. After receiving

the SetConfiguration and SetInterface commands, the application must program endpoint

registers accordingly and set this bit.

Bits 14:11 Reserved, must be kept at reset value.

Bits 10:0 MPSIZ: Maximum packet size

The application must program this field with the maximum packet size for the current logical

endpoint. This value is in bytes.

STMicroelectronics STM32F407 User Manual

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