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USB on-the-go high-speed (OTG_HS) RM0033

1186/1381 RM0033 Rev 9

OTG_HS device endpoint-x transfer size register (OTG_HS_DIEPTSIZx)

(x = 1..5, where x = Endpoint_number)

Address offset: 0x910 + 0x20 * x

Reset value: 0x0000 0000

The application must modify this register before enabling the endpoint. Once the endpoint is

enabled using the Endpoint enable bit in the device endpoint-x control registers (EPENA bit

in OTG_HS_DIEPCTLx), the core modifies this register. The application can only read this

313029282726252423222120191817161514131211109876543210

Reserved

MCNT PKTCNT XFRSIZ

rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw

Bit 31 Reserved, must be kept at reset value.

Bits 30:29 MCNT: Multi count

For periodic IN endpoints, this field indicates the number of packets that must be transmitted

per frame on the USB. The core uses this field to calculate the data PID for isochronous IN

endpoints.

01: 1 packet

10: 2 packets

11: 3 packets

Bit 28:19 PKTCNT: Packet count

Indicates the total number of USB packets that constitute the Transfer Size amount of data

for this endpoint.

This field is decremented every time a packet (maximum size or short packet) is read from

the TxFIFO.

Bits 18:0 XFRSIZ: Transfer size

This field contains the transfer size in bytes for the current endpoint. The core only interrupts

the application after it has exhausted the transfer size amount of data. The transfer size can

be set to the maximum packet size of the endpoint, to be interrupted at the end of each

packet.

The core decrements this field every time a packet from the external memory is written to the

TxFIFO.

ST STM32F207 series User Manual

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