AT43USB325 datasheet(69/109 Pages) ATMEL

69 / 109 page

3355C–USB–4/05

AT43USB325

8.1.8

Control Write Status Response State

The Function Interface Unit receives an IN token from the Host. The FIU responds with a zero

length DATA1 packet, retrying until it receives an ACK back from the Host. The FIU then asserts

a TX_COMPLETE interrupt.

8.1.9

Interrupt/Bulk IN Transfers at Function End-point

The firmware must first condition the end-point through the End-point Control Register, FEND-

P1/2/3_CNTR:

Set end-point direction: set EPDIR

Set interrupt or bulk: EPTYPE = 11 or 10

Enable end-point: set EPEN

The Function Interface Unit receives an IN token from the Host. The FIU responds with NAKs

until TX_PACKET_READY is set. The FIU then sends the data in the FIFO upstream, retrying

un til it succes s fully r e ceive s a n ACK fr om th e hos t. Finally, the FIU cle a rs th e

TX_PACKET_READY bit and asserts a TX_COMPLETE interrupt.

Read UISR

Read FCSR1/2/3

Clear TX_COMPLETE

If more data: fill FIFO, set TX Packet Ready

Wait for TX_COMPLETE interrupt

If no more data: set DATA END in FCAR1/2/3

Set UIAR[FEP1/2/3 INTACK] to clear the interrupt source

Hardware

Firmware

IN token from Host

Send DATA1(0)

ACK from Host

Set TX Complete

→ INT

Read UISR

Read CSR0

Clear TX COMPLETE, clear Data

End, set Force STALL in CAR0

Set UIAR[EP0 INTACK] to clear

the interrupt source

AT43USB325 Datasheet(PDF) 69 Page - ATMEL Corporation