Rainbow Electronics AT89C5131 - Manual (Page 116)

116
AT89C5131
4136A–USB–03/03
Function Interface Unit (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.
Figure 51. UFI Block Diagram
Figure 52. Minimum Intervention from the USB Device Firmware
Transfer
Control
FSM
DPR Control
USB Side
CSREG 0 to 7
Registers
Bank
DPR Control
mP side
FIU
User DPRAM
Up to 48 MHz
UC_sysclk
C51
Microcontroller
Interface
Asynchronous Information
Transfer
Endpoint 0
Endpoint 1
Endpoint 2
Endpoint 3
SIE
DPLL
Endpoint 4
Endpoint 5
Endpoint 6
OUT Transactions:
HOST
UFI
C51 OUT DATA0 (n bytes)
ACK
Endpoint FIFO read (n bytes)
OUT DATA1
NACK
OUT DATA1
ACK
IN Transactions:
HOST
UFI
C51 IN ACK
Endpoint FIFO write
IN
DATA1 NACK
interrupt C51
IN
DATA1
interrupt C51
Endpoint FIFO write