Protocol analysis
R&S
®
RTP
805User Manual 1337.9952.02 ─ 12
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 RTP can be triggered by the
option R&S RTP-K60. 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
RTP-K60)
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