Protocol analysis
R&S
®
RTO6
817User Manual 1801.6687.02 ─ 05
Packet
type
Name PID
value
Meaning
NAK 0x5A Data not accepted, typically equivalent with some type of EAGAIN,
meaning that the data should be resent later
STALL 0x1E A severe error has occurred, the target endpoint cannot be addressed
until it is explicitly cleared again
NYET 0x96 Only used in high-speed transfers, meaning ACK, but in the next inter-
val no data can be received, therefore the host should first apply a
PING
Special PRE 0x3C Starts a low speed transfer via a full speed bus
ERR 0x3C Indicates an error in an SPLIT transaction (using the same PID as
PRE, however
, these cannot be mistaken for each other)
SPLIT
0x78 Starts an SPLIT transaction (thus: a low speed or full speed transfer
via a high-speed bus)
PING 0xB4 Used for monitoring high-speed data flow
●
Token packets (IN, OUT
, SETUP) and PING packets have the following format:
SYNC PID ADDR ENDP CRC5 EOP
●
Start of frame packets (SOF) have the following format:
SYNC PID Frame number CRC5 EOP
●
Data packets have the following format:
SYNC PID Data CRC16 EOP
●
Handshake packets have the following format:
SYNC PID EOP
●
SPLIT packets have the following format:
SYNC PID ADDR SC PORT S E ET CRC5 EOP
Trigger possibilities
Signals on the input channels CH1 - CH4 of the R&S RT
O6 can be triggered by the
option R&S RTO6-K570. The following trigger types are available:
●
ANY Packet - Packet Sync: Triggering on the first rising slope after transmission of
the packet Sync. Various lengths according to standard (in USB 2.0: 32 bit)
●
Any token, OUT, IN, SOF, SETUP, AND-ing with user defined PID check, address,
endpoint, CRC5: For OUT, IN, SETUP, the endpoint and CRC5 follow from the bit
order, therefore such patterns can be recognized.
USB (option R&S RT
O6-K570)
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