Matrix Orbital LK202-24-USB - Manual (Page 25)

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 9: 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 is 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 10: Continued / Size Byte
Bit Description
7 Continued
6
5
4
3
Packet Size
2
1
0
Table 11: Display Return Protocol Types
Decimal Hex ASCII Description
49 0x31 ’1’ 1-Wire data
82 0x52 ’R’ Fan RPM data
Matrix Orbital LK202-24-USB 21