SPI Packet

Lepton 3 packet memory layout

Name	Size (bits)	Description
First bit	1	Should be zero
TTT Segment number	3	Segment number when packet number is 20. If packet number is not 20 then ignore it.
Packet Number	12	The packet number
Checksum	16	CRC16, CCITT, seed=0, final=0
Payload	8*160	Line of pixels values

Example of a C struct packet

#define Lepton_Height 60
#define Lepton_Width 80
#define Lepton_Packet_Payload_Size 160
struct __attribute__((__packed__)) Lepton_Packet
{
   //FTTT NNNN
   //NNNN can be ignored because those bits would make packet number too large
   uint8_t Reserved;
   //NNNN NNNN
   //Can be between 0 .. Lepton_Height
   uint8_t Number;
   //CRC16, CCITT, seed=0, final=0, FTTT = 0, Checksum = 0
   uint16_t Checksum;
   union
   {
      uint8_t Payload [Lepton_Packet_Payload_Size];
      uint16_t Line [Lepton_Width];
   };
};