"CCSDS telecommand header (bytes 2-3)" (SVC/ITC)

View Options: (help)

Focus:	Maintenance / Operation
Structures:	Abstract / Concrete

Definition:

Alignment:	2-byte boundary
APID:	720/0x2D0
Attribute(s):
C type:	unsigned short
Length:	16 bits (2 bytes)

Description:

Bitfileds for bytes 2-3 of a standard CCSDS telecommand header

Layout: (hide detail; help)

Start	Stop	Size		Item Type and Name
0	1	2		Seq_flg seq_flg
2	15	14		Seq_cnt seq_cnt

Hdr1 (bf)
|  Seq_flg seq_flg (0-1)
|  Seq_cnt seq_cnt (2-15)

typedef struct _ITC_Hdr1_Bfl {

    #if ENDIANNESS_IS_BIG

    /* CCSDS sequencing bits */
    unsigned short       seq_flg:2;

    /* CCSDS sequencing count */
    unsigned short       seq_cnt:14;

    #elif ENDIANNESS_IS_LITTLE

    /* CCSDS sequencing count */
    unsigned short       seq_cnt:14;

    /* CCSDS sequencing bits */
    unsigned short       seq_flg:2;

    #else

    #error _FILE_ ENDIANNESS NOT DEFINED

    #endif

} __attribute__((packed)) ITC_Hdr1_Bfl;

typedef union _ITC_Hdr1 {

    /* underlying unsigned short */
    unsigned short                  us;

    /* struct mapped bitfield */
    struct _ITC_Hdr1_Bfl            bf;

} ITC_Hdr1;

Fields:

Seq_cnt (index)

Attribute(s):  

Brief:  "CCSDS sequencing count"

Instance(s):  seq_cnt

Standard CCSDS sequencing count (incrementing per APID).

Seq_flg (index)

Attribute(s):  

Brief:  "CCSDS sequencing bits"

Instance(s):  seq_flg

Standard CCSDS sequencing bits.

Used by:

CmdHeader