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Sequence 2
1. Detection of a PREAMBLE - switch to low speed
2. Look for IN packet and a following DATA packet
and then switch back to high speed. If a DATA
packet is not received within the time-out period
(18 bit times), the Analysis Probe will switch back
to high speed.
3. In high speed look for PREAMBLE and handshake
If the Analysis Probe is placed on a low speed only
segment the low speed only switch must be placed in
the on position (LED lit). This is because on a low
speed only segment the Host or Hub will not send a
Preamble PID. NOTE: The low speed only switch
need only be placed in the ON position if the
Analysis Probe is placed on a LOW SPEED ONLY
SEGMENT (no high speed traffic present).
If users are on a mixed high speed/low speed
segment and suspect that low speed/high speed USB
specification protocol is not being adhered to, the
following steps should be taken.
1. Acquire USB traffic with the Analysis Probe Low
Speed only switch in the OFF position.
2. Acquire USB traffic with the Analysis Probe Low
Speed Only switch in the ON position.
3. Note any differences and refer to timing mode to
determine any out of specification conditions.
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