Ubisys IEEE 802.15.4 usb stic with wireshark firmware Manual de usuario descargar pdf (Pagina 14)

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Figure 8: Dissector and Raw Binary Detail Views

Notice that the IEEE 802.15.4 frame is encapsulated in a ZEPv2 frame, which is transferred via

UDP/IP, and Ethernet (RNDIS). The ZEP frame includes channel number information and an LQI value

derived from individual correlation and RSSI values and a time-stamp

that is accurate to approximately

one PHY symbol period (16 microseconds).

The time-stamp, despite being specified as an absolute NTP time-stamp, is rather meant as a relative

time-stamp, which starts at a fixed time, e.g. January 1, 2012 in firmware revision 1.03 and below, or

January 1, 2015, 00:00h in firmware revision 1.04, when the device is powered. The underlying

hardware timer hosts a 32-bit register incrementing at a rate of 62.500Hz (corresponding to the PHY s

symbol frequency), which results in a roll-over after approximately 19 hours of operation, when the

time-stamp restarts at its pre-configured absolute start-time again.

Individual RSSI and LQI correlation values are available in the FCS field. Notice that this field is in

CC2420 format, i.e. the frame check sequence is not the value actually transmitted over the air. Instead

of the 16-bit CRC, there is only one bit that determines whether the FCS was correct. The remaining

The time-stamp is valid in firmware versions 1.04 and above

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Ubisys IEEE 802.15.4 usb stic with wireshark firmware Manual de usuario Pagina 14