FLIR LEPTON® Engineering Datasheet
The information contained herein does not contain technology as defined by the EAR, 15 CFR 772, is publicly available,
and therefore, not subject to EAR. NSR (6/14/2018).
Information on this page is subject to change without notice.
Lepton Engineering Datasheet, Document Number: 500-0659-00-09 Rev: 203
48
160 or 240 bytes (depending upon bit resolution setting)
For video packets, the header includes a 2-byte ID and a 2-byte CRC. The ID field is a 12-bit packet number as
shown in Figure 21 (the leading 4 bits of the ID field are reserved and are not part of the packet number). Note
that packet numbering restarts at zero on each new frame. The CRC portion of the packet header contains a 16-
bit cyclic redundancy check (CRC), computed using the following polynomial:
x
16
+ x
12
+ x
5
+ x
0
The CRC is calculated over the entire packet, including the ID and CRC fields. However, the four most-significant
bits of the ID and all sixteen bits of the CRC are set to zero for calculation of the CRC. There
is no requirement for
the host to verify the CRC. However, if the host does find a CRC mismatch, it is
recommended to re-synchronize the
VoSPI stream to prevent potential misalignment.
Figure 21 - Video Packet
Video pixels for one video line
At the beginning of SPI video transmission until synchronization is achieved (see VoSPI Stream, page 41), and in
the idle period between frames, Lepton transmits discard packets until it has a new frame from its imaging
pipeline. As shown in Figure 22, the 2-byte ID field for discard packets is always xFxx (where 'x' signifies a “don't
care” condition). Note that VoSPI-enabled cameras do not have vertical resolution approaching 3840 lines
(0xF00), and therefore it is never possible for the ID field in a discard packet to be mistaken for a video line.
Figure 22 - Discard Packet
Discard data (same number of bytes as video packets)
For video packets, the payload contents depend upon the selected bit resolution.
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