Reference Packet Parameter
Packet Parameter
The algorithm calculates the SYNC field length, EOP length, and the Inter-Packet gap. The acceptable
range of EOP for all transmitted packets (except SOFs) must be between 7.5 and 8.5 bits. The packet
parameter al
gorithm calculates and verifi es the EOP depending on this range.
The acceptable range of inter-packet gap should be between 88 bits to 192 bits. T he SYNC field for all
transmitte
d packets is calculated by counting the bits to check for 32-bit SYNC field. The inter-packet
delay and SYNC status is calculated between the respective EOP indexes of the packets. The EOP width
in time is calculated by dividing the EOP width by the signalling rate of 480 Mbps.
Oscilloscope setup details:
The appli
cation sets the oscilloscope automatically to the following values:
Horizontal Scale: 400 ns
Record Length: 50 K
Vertical Scale: 200 mV
Trigger Type Pulse Width
Trigger Hold Off: 5 s
Resu
me
This
test calculates the device/HUB resume High-speed operation, indicated by High-spe ed SOF packets
(with 400 mV nominal amplitude) following the K state driven by the host controller. For the Host, this is
the time between the falling edge of D+ and the First SOF. This should not exceed 3.0 ms. To get the
Suspend signal, hot-plug the unit under test (device) and measure the signaling with single-ended probes
on both lines. The application analyzes data for the following:
Resume Time
Amplitude
TDSUSB2 Universal Serial Bus Measurements Package 187
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