at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 119

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

Function Interface Unit (FIU)
Figure 55. UFI Block Diagram
Figure 56. Minimum Intervention from the USB Device Firmware
4136C–USB–04/05
HOST
UFI
C51
IN Transactions:
HOST
UFI
C51
OUT Transactions:
DPLL
SIE
OUT DATA0 (n bytes)
IN
Endpoint FIFO write
NACK
FIU
The Function Interface Unit provides the interface between the AT89C5131 and the SIE.
It manages transactions at the packet level with minimal intervention from the device
firmware, which reads and writes the endpoint FIFOs.
DPR Control
USB Side
Transfer
Control
FSM
ACK
Asynchronous Information
Transfer
IN
interrupt C51
User DPRAM
DATA1
Endpoint FIFO read (n bytes)
OUT
Endpoint 6
Endpoint 5
Endpoint 4
Endpoint 3
Endpoint 2
Endpoint 1
Endpoint 0
DATA1
IN
NACK
CSREG 0 to 7
DPR Control
mP side
DATA1
Registers
Bank
OUT
ACK
interrupt C51
DATA1
C51
Microcontroller
Interface
Up to 48 MHz
UC_sysclk
Endpoint FIFO write
AT89C5131
ACK
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