AT89C5131-PLTIL ATMEL Corporation, AT89C5131-PLTIL Datasheet - Page 121

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AT89C5131-PLTIL

Manufacturer Part Number
AT89C5131-PLTIL
Description
8-bit Flash Microcontroller with Full Speed USB Device
Manufacturer
ATMEL Corporation
Datasheet
Bulk/Interrupt
Transactions
Bulk/Interrupt OUT
Transactions in Standard
Mode
4136B–USB–09/03
Bulk and Interrupt transactions are managed in the same way.
Figure 59. Bulk/Interrupt OUT transactions in Standard Mode
An endpoint will be first enabled and configured before being able to receive Bulk or
Interrupt packets.
When a valid OUT packet is received on an endpoint, the RXOUTB0 bit is set by the
USB controller. This triggers an interrupt if enabled. The firmware has to select the cor-
responding endpoint, store the number of data bytes by reading the UBYCTLX and
UBYCTHX registers. If the received packet is a ZLP (Zero Length Packet), the
UBYCTLX and UBYCTHX register values are equal to 0 and no data has to be read.
When all the endpoint FIFO bytes have been read, the firmware will clear the RXOUTB0
bit to allow the USB controller to accept the next OUT packet on this endpoint. Until the
RXOUTB0 bit has been cleared by the firmware, the USB controller will answer a NAK
handshake for each OUT requests.
If the Host sends more bytes than supported by the endpoint FIFO, the overflow data
won’t be stored, but the USB controller will consider that the packet is valid if the CRC is
correct and the endpoint byte counter contains the number of bytes sent by the Host.
OUT
OUT
OUT
OUT
HOST
DATA1
DATA0 (n bytes)
DATA1
DATA1
ACK
ACK
NAK
NAK
UFI
RXOUTB0
RXOUTB0
Endpoint FIFO read byte 1
Endpoint FIFO read byte 2
Endpoint FIFO read byte n
Endpoint FIFO read byte 1
Clear RXOUTB0
C51
AT89C5131
121

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