Adding TyreGuard 400 TPMS

[Topper69]

No description provided.

[zuckschwerdt]

Note that

• crc8(&b[0], 10, 0x31, 0xdd) != PacketCRC) is identical to crc8(b, 11, 0x31, 0xdd) != 0 which is preferred.
• temp_c = (int) b[8] - 40; does not need the cast, it's already int (C integer promotion)
• the doc comment needs to be well-formed markdown, indent code blocks by 4 spaces, put dashes in lists.

[Topper69]

crc8 code + temp_c has been changed.
About the docs, not sure i have fixed all what you ask for :/ (not sure i have fully understood).

[zuckschwerdt]

Sorry for being unclear, the markdown should not be indented, just the code blocks:

/**
TPMS TyreGuard 400 from Davies Craig.

...
- Length          : 22 bytes long

Packet layout:

     1    2    3    4    5    6    7    8   9   10  11  12  13  14  15  16  17   18   19   20   21  22
     S/P  S/P  S/P  S/P  S/P  S/P  S/P  ID  ID  ID  ID  ID  ID  ID  Pr  Pr  Temp Temp Flg  Flg  CRC CRC
    
- S/P   : preamble/sync "0xfd5fd5f" << always fixed
...

[zuckschwerdt]

Oh and, pressure_kpa = b[7] | ((flags & 0x10)<<4) | ((flags & 0x20)<<4) | ((flags & 0x40)<<4) ; is pressure_kpa = b[7] | ((flags & 0x70) << 4); (1+2+4=7)

[Topper69]

Oh and, pressure_kpa = b[7] | ((flags & 0x10)<<4) | ((flags & 0x20)<<4) | ((flags & 0x40)<<4) ; is pressure_kpa = b[7] | ((flags & 0x70) << 4); (1+2+4=7)

Many thanks. Updated.