Datasheet

AT89C5132

4173C–USB–07/04

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 48. SIE Block Diagram

Function Interface Unit (UFI) The Function Interface Unit provides the interface between the AT89C5132 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 50 shows typical USB IN and OUT transactions reporting the split in the hard-

ware (UFI) and software (C51) load.

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)

Data Ou