MC908JB16DWE Datasheet, PDF (170/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
Each USB transaction is comprised of a series of packets. The USB
module supports the packet types shown in Figure 11-4. Token packets
are generated by the USB host and decoded by the USB device. Data
and handshake packets are both decoded and generated by the USB
device, depending on the type of transaction.
Token Packet:
IN
OUT
SYNC PID
SETUP
Data Packet:
DATA0
SYNC PID
DATA1
Handshake Packet:
ACK
NAK
SYNC PID
STALL
PID ADDR ENDP CRC5 EOP
PID
DATA
CRC16 EOP
0 – 8 Bytes
PID EOP
Figure 11-4. Supported USB Packet Types
The following sections detail each segment used to form a complete
USB transaction.
11.5.1.1 Sync Pattern
The NRZI bit pattern shown in Figure 11-5 is used as a synchronization
pattern and is prefixed to each packet. This pattern is equivalent to a
data pattern of seven 0s followed by a 1 ($80).
NRZI Data
Encoding
SYNC PATTERN
Idle
Figure 11-5. Sync Pattern
PID0 PID1
Technical Data
170
Universal Serial Bus Module (USB)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor