GMS30C7201 Datasheet, PDF (209/352 Pages) Hynix Semiconductor – 60MHz operation frequency Low power consumption

Fast AMBA Peripherals
Digital Phase Lock Loop
The Digital Phase Lock Loop module takes the incoming data signals from the USB,
synchronizes them to the 48MHz input clock, and then looks for USB data transitions. Based
on these transitions, the module creates a divide-by-4 clock called the usbclock. Data is then
output from this module synchronous to the usbclock.
Input NRZI decode and bit-unstuff
The Input NRZI decode and bit-unstuff module extracts the NRZI encoded data from the
incoming USB data. Transitions on the input serial stream indicate a 0, while no transition
indicates a 1. Six ones in a row cause the transmitter to insert a 0 to force a transition, therefore
any detected zero bit that occurs after six ones is thrown out.
Packet Decoder
The Packet Decoder module receives incoming data bits and decodes them to detect packet
information. It checks that the PID (Packet ID) is valid and was sent without error. After
decoding the PID, the remainder of the packet is split into the address, endpoint, and CRC5
fields, if present. The CRC Checker is notified to verify the data using the incoming CRC5 field.
If the packet is a data packet, the data is collected into bytes and passed on with an associated
valid bit. Table 12-35: Supported PID Types shows the PID Types that are decoded (marked as
either Receive or Both). At the end of the packet, either the packetok or packetnotok signal is
asserted. Packetnotok is asserted if any error condition arose (bad valid bit, bit-stuff, bad PID,
wrong length of a field, CRC error, etc.).
PID Type
OUT
IN
SOF
SETUP
DATA0
DATA1
ACK
NAK
STALL
PRE
Value
Send/Receive
4’b0001
Receive
4’b1001
Receive
4’b1101
Receive
4’b0000
Receive
4’b0011
Both
4’b1011
Both
4’b0010
Both
4’b1010
Send
4’b1110
Send
4’b1100
Receive
Table 12-35: Supported PID Types
Packet Encoder
The Packet Encoder creates outgoing packets based on signals from the DEV. Table 12-35:
Supported PID Types shows the PID Types that can be encoded (marked as Send or Both). For
each packet type, if the associated signal sendtype is received from the DEV, the packet is
created and sent. Upon completion of the packet, packettypesent is asserted to inform the DEV
of the successful transmission. The Packet Encoder creates the outgoing PID, grabs the data
from the DEV a byte at a time, signals the CRC Generator to create the CRC16 across the data
field, and then sends the CRC16 data. The serial bits are sent to the Output bit stuff and NRZI
encoder.
GMS30C7201 Data Sheet
12-55