Manual

115
AT89C5131
4136A–USB–03/03
Serial Interface Engine (SIE) The SIE performs the following functions:
• NRZI data encoding and decoding.
• Bit stuffing and un-stuffing.
• CRC generation and checking.
• Handshakes.
• TOKEN type identifying.
• Address checking.
• Clock generation (via DPLL).
Figure 50. SIE Block Diagram
End of Packet
Detection
Start of Packet
Detection
D+
D-
Clock
Recovery
SYNC Detection
PID Decoder
Address Decoder
Serial to
Parallel Conversion
CRC5 and CRC16
Generation/Check
USB Pattern Generator
Parallel to Serial Converter
Bit Stuffing
NRZI Converter
CRC16 Generator
NRZI ‘NRZ
Bit Un-stuffing
Packet Bit Counter
Clk48
(48 MHz)
SysClk
(12 MHz)
DataIn [7:0]
DataOut
8
8