Matrix Orbital LK204-24-USB - Manual (Page 26)

protocol is used for reading fan speeds and retrieving 1-wire bus information. The basic structure of the
protocol is described in the Table below.
Table 10: Display Return Protocol
Offset
(Bytes)
Length
(Bytes)
Value Description
0 2 0x23 0x2A Preamble
2 1 Continued / Size
3 1 Packet Type
4 1–127 Packet Data
The first two bytes are the standard preamble to separate the protocol from returned keypresses. The
next byte is described in the Table below. The CONT flag specifies that the data will be continued in the
next DRP packet. The lower seven bits contains the size of the data section excluding the four byte header.
The type specifies what type of information is contained in the packet. Finally, the data returned is specific
to the packet type.
Table 11: Continued / Size Byte
Bit Description
7 Continued
6
5
4
3 Packet Size
2
1
0
Table 12: Display Return Protocol Types
Decimal Hex ASCII Description
49 0x31 ’1’ 1-Wire data
82 0x52 ’R’ Fan RPM data
Matrix Orbital LK204-24-USB 22