Rainbow Electronics AT89C51SND1C - Manual (Page 82)

82
AT8xC51SND1C
4109E–8051–06/03
Serial Interface Engine (SIE) The SIE performs the following functions:
• NRZI data encoding and decoding.
• Bit stuffing and unstuffing.
• CRC generation and checking.
• ACKs and NACKs automatic generation.
• TOKEN type identifying.
• Address checking.
• Clock recovery (using DPLL).
Figure 57. SIE Block Diagram
8
Start of Packet
Detector
Clock
Recover
SYNC Detector
PID Decoder
Address Decoder
Serial to Parallel
Converter
CRC5 & CRC16
Generator/Check
USB Pattern Generator
Parallel to Serial Converter
Bit Stuffing
NRZI Converter
CRC16 Generator
NRZI ‘ NRZ
Bit Unstuffing
Packet Bit Counter
End of Packet
Detector
USB
CLOCK
48 MHz
SysClk
Data In
D+
D-
(12 MHz)
8
Data Out